Advances and limitations of the Environmental Seismic Intensity scale ESI 2007 regarding near-field and far-field effects from recent earthquakes in Greece; implications for the seismic hazard; assessment


Papanikolaou, I.D.; Papanikolaou, D.I.; Lekkas, E.L.

Geological Society Special Publications 316: 11-30

2009


The new Environmental Seismic Intensity scale (ESI 2007), introduced by INQUA, incorporates the advances and achievements of paleoseismology and earthquake geology and evaluates earthquake size and epicenter solely from the earthquake environmental effects (EEE). This scale is tested and compared with traditional existing scales for the 1981 Alkyonides earthquake sequence in the Corinth Gulf (Ms=6.7, Ms=6.4, Ms=6.3), the 1993 Pyrgos event (Ms=5.5) and the 2006 Kythira event (Mw=6.7). These earthquakes were of different magnitudes, focal mechanisms and focal depths and produced well-documented environmental effects. The ESI 2007 intensity values and the isoseismal pattern for the 1993 Pyrgos and the 2006 Kythira events are similar to those resulting from the traditional scales, demonstrating that for moderate intensity levels (VII and VIII) the ESI 2007 and the traditional scales comply well. In contrast, the 1981 Alkyonides earthquake sequence shows that there is an inconsistency between the ESI 2007 and the traditional scales both in the epicentral area, where higher ESI 2007 intensity values have been assigned, and for the far-field effects. The ESI 2007 scale offers higher objectivity in the process of assessing macroseismic intensities, particularly in the epicentral area, than traditional intensity scales that are influenced by human parameters. The ESI 2007 scale follows the same criteria-environmental effects for all events and can compare not only events from different settings, but also contemporary and future earthquakes with historical events. A reappraisal of historical earthquakes so as to constrain the ESI 2007 scale may prove beneficial for seismic hazard assessment by reducing the uncertainty implied in the attenuation laws, which constitute one of the most important seismic hazard parameters.

Advances
and
limitations
of
the
Environmental
Seismic
Intensity
scale
(ESI
2007)
regarding
near-field
and
far-field
effects
from
recent
earthquakes
in
Greece:
implications
for
the
seismic
hazard
assessment
I.
D.
PAPANIKOLA0U
1,2
*,
D.
I.
PAPANIKOLA0U
2
&
E.
L.
LEKKAS
2
1
Benfield-UCL
Hazard
Research
Centre,
Department
of
Earth
Sciences,
University
College
London,
Gower
Street,
WC1E
6BT
London,
UK
2
Natural
Hazards
Laboratory,
Department
of
Dynamic,
Tectonic
and
Applied
Geology,
Faculty
of
Geology
and
Geoenvironment,
National
and
Kapodistrian
University
of
Athens,
Panepistimioupolis
Zografou,
157-84
Athens,
Greece
*Corresponding
author
(e-mail:
i.papanikolaou@ucl.ac.uk)
Abstract:
The new
Environmental
Seismic
Intensity
scale
(ESI
2007),
introduced
by
INQUA,
incorporates
the
advances
and
achievements
of
palaeoseismology
and
earthquake
geology
and
evaluates
earthquake
size
and
epicentre
solely
from
the
earthquake
environmental
effects
(EEE).
This
scale
is
tested
and
compared
with
traditional
existing
scales
for
the
1981
Alkyonides
earthquake
sequence
in
the
Corinth
Gulf
(Ms
=
6.7,
Ms
=
6.4,
Ms
=
6.3),
the
1993
Pyrgos
event
(Ms
=
5.5)
and
the
2006
Kythira
event
(Mw
=
6.7).
These
earthquakes
were
of
different
magni-
tudes,
focal
mechanisms
and
focal
depths
and
produced
well-documented
environmental
effects.
The
ESI
2007
intensity
values
and
the
isoseismal pattern
for
the
1993
Pyrgos
and
the
2006
Kythira
events
are
similar
to
those
resulting
from
the
traditional
scales,
demonstrating
that
for
moderate
intensity levels
(VII
and
VIII)
the
ESI
2007
and
the
traditional
scales
comply
well.
In
contrast,
the
1981
Alkyonides
earthquake
sequence
shows
that
there
is
an
inconsistency
between
the
ESI
2007
and
the
traditional
scales
both
in
the
epicentral
area,
where
higher
ESI
2007
intensity
values
have
been
assigned,
and
for
the
far-field
effects.
The
ESI
2007
scale
offers
higher
objectivity
in
the
process
of
assessing
macroseismic
intensities,
particularly
in
the
epicentral
area,
than
traditional
intensity
scales
that
are
influenced
by
human
parameters.
The
ESI
2007
scale
follows
the
same
criteria—environmental
effects
for
all
events
and
can
compare
not
only
events
from
different
settings,
but
also
contemporary
and
future
earthquakes
with
histori-
cal
events.
A
reappraisal
of
historical
earthquakes
so
as
to
constrain
the
ESI
2007
scale
may
prove
beneficial
for
seismic
hazard
assessment
by
reducing
the
uncertainty
implied
in
the
attenuation
laws,
which
constitute
one
of
the
most
important
seismic
hazard
parameters.
A
macroseismic
intensity
value
represents
the
macroseismic
information
obtained
by
the
quanti-
fication
of
the
effects
and
damage
produced
by
an
earthquake.
The
macroseismic
intensity
is
not
solely
used
for
the
description
of
earthquake
effects,
but
is
a
major
seismic
hazard
parameter
as
well.
The
use
of
macroseismic
intensity
as
a
seismic
hazard parameter
predominates
internation-
ally,
and
more
than
60%
of
countries
have
hazard
assessment
exclusively
expressed
in
terms
of
inten-
sity
(McGuire
1993).
The
reason
is
that
the
histori-
cal
record
and
the
attenuation
laws
for
large
earthquakes
are
usually
expressed
in
intensity
values
(e.g.
Grandori
et
al.
1991),
whereas
in
case
of
seismic
risk
management
and
earthquake
loss
estimation
seismic
intensity
is
preferred
due
to
its
direct
representation
of
earthquake
damage
(Coburn
&
Spence
2002).
However,
when
using
the
effects
on
man
and
the
manmade
environment
to
assess
the
macroseis-
mic
intensity,
then
intensity
will
tend
to
reflect
mainly
the
economic
development
and
the
cultural
setting
of
the
area
that
experienced
the
earthquake,
instead
of
its
'strength'
(Serva
1994).
This
led
to
the
development
and
implementation
of
the
Environmental
Seismic
Intensity
2007
scale.
The
newly
introduced
ESI
2007
scale
(Michetti
et
al.
2007)
is
developed
within
the
INQUA
Subcommis-
sion
on
Palaeoseismicity,
is
the
result
of
the
revi-
sions
of
previous
versions,
provisionally
named
as
INQUA
EEE
scale
(e.g.
Michetti
et
al.
2004)
and
aims
at
evaluating
earthquake
size
and
epicentre
solely
from
the
earthquake
environmental
effects
(EEE).
The
EEE
are
not
influenced
by
human
parameters
such
as
effects
on
people
and
the
manmade
environment
as
the
traditional
intensity
From:
REICHERTER,
K.,
MICHETTI,
A.
M.
&
SILVA,
P.
G.
(eds)
Palaeoseismology:
Historical
and
Prehistorical
Records
of
Earthquake
Ground
Effects
for
Seismic
Hazard
Assessment.
The
Geological
Society,
London,
Special
Publications,
316,
11-30.
DOI:
10.1144/SP316.2
0305-8719/09/$15.00
©
The
Geological
Society
of
London
2009.
12
I.
D.
PAPANIKOLAOU
ET
AL.
scales
(MCS,
MM,
EMS
1992,
etc.)
predominantly
imply.
It
is
a
common
notion
that
two
earthquakes
that
produce
similar
environmental
effects,
thus
having
the
same
ESI
2007
intensity
degree,
but
occur
on
sites
that
are
different
in
terms
of
cultural
and
economic
development,
usually
record
signifi-
cantly
different
intensity
values
as
far
as
the
traditional
scales
are
concerned.
In
particular,
if
one
of
these
earthquakes
occurs
in
a
developing
country
it
tends
to
record
a
higher
macroseismic
intensity
value
compared
to
a
developed
seismic-
prone
country.
Over
the
last
few
decades
palaeoseismology
and
earthquake
geology
have
contributed
significantly
to
our
understanding
concerning
the
EEE
and
more
importantly
they
have
provided
a
quantitative
analysis
and
description
of
these
effects.
These
effects
have
been
incorporated
into
the
ESI
2007
scale
(Table
1).
Among
other
advantages
this
scale:
(i)
allows
the
accurate
assessment
of
intensity
in
sparsely
populated
areas,
(ii)
provides
a
reliable
estimation
of
earthquake
size
with
increasing
accu-
racy
towards
the
highest
levels
of
the
scale,
where
traditional
scales
saturate
and
ground
effects
are
the
only
ones
that
permit
a
reliable
estimation
of
earthquake
size,
and
(iii)
allows
comparison
among
future,
recent
and
historical
earthquakes
(Michetti
et
al.
2004).
Overall,
this
scale
is
intended
to
integrate
existing
scales,
not
to
replace
them,
and
can
encourage
greater
objectivity
in
the
process
of
seismic
intensity
assessment,
through
independence
from
the
variable
nature
of
man
and
his
infra-
structure
(Michetti
et
al.
2004).
The
use
of
the
ESI
2007
scale
alone
is
recommended
only
when
effects
on
humans
and
manmade
structures:
(i)
are
absent
or
too
scarce
(i.e.
desert
or
sparsely
populated
areas),
and
(ii)
saturate
(i.e.
for
intensity
X
to
XII)
losing
their
diagnostic
value
(Michetti
et
al.
2007).
Although
the
traditional
intensity
scales
consider
environmental
effects
for
the
evaluation
of
seismic
intensity,
these
effects
are
not
properly
weighted
and
are
systematically
neglected.
For
example,
the
traditional
scales
do
not
differentiate
between
primary
and
secondary
effects
and
do
not
use
a
quantitative
approach
for
the
effects
on
nature
(Michetti
et
al.
2007).
This
is
nicely
illustrated
with
the
EMS
1992
(European
Macroseismic
Scale)
that
forms
an
updated
version
of
the
tra-
ditional
intensity
scales
(predominantly
the
MSK).
The
EMS
1992
was
developed
to
be
more
easily
implemented
in
urban
areas
giving
even
more
emphasis
to
manmade
structures.
In
particular,
it
includes
new
building
types
and
modern
construc-
tion
materials,
offers
an
easier
recognition
of
the
structure
vulnerability
class
and
a
more
precise
evaluation
of
the
grade
of
damage
(Grunthal
1993).
In
this
paper
we:
(a)
assess
intensities
in
the
ESI
2007
scale
for
several
sites
regarding
three
relatively
recent
events
that
occurred
in
Greece,
(b) test
and
compare
the
ESI
2007
scale
with
existing
traditional
macroseismic
intensity
scales,
and
(c)
discuss
possible
implications
for
seismic
hazard
assessment.
The
success
of
the
newly
intro-
duced
intensity
scale
also
depends
on
its
impact
on
seismic
hazard
assessment.
Selected
earthquakes
An
earthquake
sequence
and
two
events
have
been
chosen
for
our
current
study
(Fig.
1).
These
include the
1981
Alkyonides
earthquake
sequence
in
the
Corinth
Gulf
(Ms
=
6.7,
Ms
=
6.4,
Ms
=
6.3),
the
1993
Pyrgos
event
(Ms
=
5.5)
and
the
2006
Kythira
event
(Mw
=
6.7).
These
earthquakes
have
been
carefully
selected
so
as
to
include
events
of
different
magnitudes,
focal
mechanisms
and
focal
depths.
Moreover,
they
all
produced
well
documented
environmental
effects
that
allow
us
both
to
test
the
newly
introduced
ESI
2007
scale
and
compare
it
with
the
existing
scales.
In
particular,
the
1981
Alkyonides
earthquake
sequence
produced
significant
primary
surface
ruptures,
the
1993
Pyrgos
event
was
on
the
threshold
of
primary
fault-
ing,
producing
only
secondary
but
widespread
effects,
whereas
the
2006
Kythira
earthquake
was
a
deep
event
that
generated
only
minor
secondary
effects.
The
1993
Pyrgos
earthquake
The
26
March
1993
Pyrgos
(Ms
=
5.5)
earthquake
in
the
Western
Peloponnese
produced
a
maximum
intensity
VIII
on
the
EMS
1992
scale
(Lekkas
1996),
affecting
the
town
of
Pyrgos,
where
about
50%
of
the
buildings
suffered
some
form
of
dam-
age
(Figs
2
and
3a).
The
main
shock
of
Ms
=
5.5
occurred
about
3
km
south
of
the
town
of
Pyrgos
(Stavrakakis
1996).
Two
foreshocks
of
Ms
=
5.0
(in
the
offshore
area
with
thrust
faulting)
and
Ms
=
5.1
(normal
faulting
NE—SW
plane
dipping
southwards)
occurred
13
and
2
minutes
before
the
main
shock
(Stavrakakis
1996).
Papanastassiou
et
al.
(1994)
determined
that
the
fault
plane
solution
is
characterized
by
thrust
oblique
faulting
on
a
fault
plane
striking
NNE—SSW
and
dipping
SE
(strike
14°
dip
70°
rake
158°),
which
according
to
Stavrakakis
(1996)
best
fits
the
observed
macro-
seismic
field.
A
similar
solution
has
been
proposed
by
Dziewonski
et
al.
(1994)
(NP1
strike
122°,
dip
60°,
rake
5°,
and
NP2
strike
30°,
dip
86°,
rake
150°)
and
Melis
et
al.
(1994).
However,
Koukouvelas
et
al.
(1996)
proposed
that
the
Pyrgos
earthquake
was
caused
by
oblique-normal
slip
on
a
north-dipping
WNW-trending
fault.
Indeed,
most
outcropping
active
faults
in
the
area
are
normal
east—west
trending
faults
(e.g.
Lekkas
et
al.
2000;
Table
1.
Summary
of
the
Environmental
Seismic
Intensity
scale
(ESI
2007)
for
intensities
VII—X
(Michetti
et
al.
2007)
Surface
faulting
Primary
effects
observed
very
rarely.
VDT
Heavily
damaging
Extensive
effects
on
the
environment
Primary
effects
observed
rarely.
Ground
ruptures
(surface
faulting)
may
develop,
up
to
several
hundred
meters
long,
with
offsets
not
exceeding
a
few
cm,
particularly
for
very
shallow
focus
earthquakes.
Tectonic
subsidence
or
uplift
with
maximum
values
on
the
order
of
a
few
centimetres
may
occur.
Small
to
moderate
(10
3
-10
5
m
3
)
landslides
widespread
in
prone
areas;
their
size
is
sometimes
large
(10
5
-10
6
m
3
).
Ruptures,
slides
and
falls
affect
riverbanks
and
artificial
embankments
in
loose
sediment
or
weathered/
fractured
rock.
The
affected
area
is
in
the
order
of
100
km
2
.
IX
Destructive
Environmental
effects
are
a
widespread
source
of
considerable
hazard
and
become
important
for
intensity
assessment
Primary
effects
observed
commonly.
Ground
ruptures
(surface
faulting)
develop,
up
to
a
few
km
long,
with
offsets
generally
in
the
order
of
several
cm.
Tectonic
subsidence
or
uplift
of
the
ground
surface
with
maximum
values
in
the
order
of
a
few
decimetres may
occur.
Landsliding
widespread
in
prone
areas,
also
on
gentle
slopes;
where
equilibrium
is
unstable
(steep
slopes
of
loose/
saturated
soils;
rock
falls
on
steep
gorges,
coastal
cliffs)
their
size
is
frequently
large
(10
5
m
3
),
sometimes
very
large
(10
6
m
3
).
Riverbanks,
artificial
embankments
and
excavations
(e.g.
road
cuts,
quarries)
frequently
collapse.
The
affected
area
is
in
the
order
of
1000
km
2
.
X
Very
destructive
Effects
in
the
environment
become
a
leading
source
of
hazards
and
are
critical
for
intensity
assessment
Primary
ruptures
become
leading.
Surface
faulting
can
extend
for
few
tens
of
km,
with
offsets
from
tens
of
cm
up
to
a
few
metres.
Gravity
grabens
and
elongated
depressions
develop;
Tectonic
subsidence
or
uplift
with
maximum
values
in
the
order
of
few
meters
may
occur.
Large
landslides
and
rock-falls
(>10
5
-10
6
m
3
)
are
frequent,
practically
regardless
of
equilibrium
state
of
the
slopes,
causing
temporary
or
permanent
barrier
lakes.
River
banks,
artificial
embankments,
and
sides
of
excavations
typically
collapse.
Levees
and
earth
dams
may
even
incur
serious
damage.
The
affected
area
is
in
the
order
of
5000
km
2
.
EEE
type/degree
VII
Damaging
Appreciable
effects
on
the
environment
Slope
movements
Scattered
landslides
occur
in
prone
areas;
(steep
slopes
of
loose/
saturated
soils;
rock
falls
on
steep
gorges,
coastal
cliffs)
their
size
is
sometimes
significant
(10
3
-
10
5
m
3
.
The
affected
area
is
in
the
order
of
10
km
2
.
try
cn
,--,
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ts..)
9
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cn
trl
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M
n
trl
trl
R.
cn
t
4,
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cn
4
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.
)
›.
cn
cn
trl
cn
cn
4
trl
4
(Continued)
Table
1.
Continued
EEE
type/degree
VII
Damaging
Appreciable
effects
on
the
environment
VIII
Heavily
damaging
Extensive
effects
on
the
environment
IX
Destructive
Environmental
effects
are
a
widespread
source
of
considerable
hazard
and
become
important
for
intensity
assessment
X
Very
destructive
Effects
in
the
environment
become
a
leading
source
of
hazards
and
are
critical
for
intensity
assessment
Fractures
up
to
50
cm
wide
and
up
to
hundred
metres
long
are
commonly
observed
in
loose
alluvial
deposits
and/or
saturated
soils;
in
rare
cases
fractures
up
to
1
cm
can
be
observed
in
competent
dry
rocks.
Decimetric
cracks
common
in
paved
roads,
as
well
as
small
pressure
undulations.
Liquefaction
may
be
frequent
in
the
epicentral
area;
sand
boils
up
to
c.
1
m
in
diameter;
localized
lateral
spreading
and
settlements
(subsidence
up
to
c.
30
cm),
with
fissuring
parallel
to
waterfront
areas
(river
banks,
lakes,
canals,
seashores).
Waves
up
to
1-
2
m
high
develop
in
nearshore
areas
and
may
damage
of
wash
away
objects
of
variable
size.
Fractures
up
to
100
cm
wide
and
up
to
hundred
metres
long
are
commonly
observed
in
loose
alluvial
deposits
and/or
saturated
soils;
in
competent
rocks
they
can
reach
up
to
10
cm.
Significant
cracks
common
in
paved
(asphalt
or
stone)
roads,
as
well
as
small
pressure
undulations.
Liquefaction
and
water
upsurge
are
frequent;
sand
boils
up
to
3
m
in
diameter;
frequent
lateral
spreading
and
settlements
(subsidence
of
more
than
c.
30
cm),
with
fissuring
parallel
to
waterfront
areas
(river
banks, lakes,
canals,
seashores).
Metre-high
waves
develop
in
still
and
running
waters.
Tsunamis
may
reach
the
coastal
areas
with
runups
of
up
to
several
metres
flooding
wide
areas.
Small
boulders
and
tree
trunks
may
be
thrown
in
the
air.
Open
ground
cracks
up
to
more
than
1
m
wide
and
up
to
hundred
metres
long
are
frequent,
mainly
in
loose
alluvial
deposits
and/or
saturated
soils;
in
competent
rocks
opening
reaches
several
decimetres.
Wide
cracks
develop
in
paved
(asphalt
or
stone)
roads,
as
well
as
pressure
undulations.
Liquefaction,
with
water
upsurge
and
soil
compaction,
may
change
the
aspect
of
wide
zones;
sand
volcanoes
even
more
than
6
m
in
diameter;
vertical
subsidence
even
>1
m;
large
and
long
fissures
due
to
lateral
spreading
are
common.
Metre-high
waves
develop
in
still
and
running
waters.
Tsunamis
may
reach
the
shores
with
runups
exceeding
5
m
flooding
flat
areas
for
thousands
of
metres
in
land.
Boulders
(diameter
in
excess
of
2-3
m)
can
be
thrown
in
the
air.
Ground
cracks
Fractures
up
to
5-10
cm
wide
and
up
to
hundred
metres
long
commonly
in
loose
alluvial
deposits
and/or
saturated
soils;
Centimetre-wide
cracks
common
in
paved
(asphalt
or
stone)
roads.
Ground
Rare
cases
of
liquefaction,
with
sand
settlements
boils
up
to
50
cm
in
diameter,
in
collapse/
areas
most
prone
to
this
tsunami/other
phenomenon
(highly
susceptible,
effects
recent,
alluvial
and
coastal
deposits,
shallow
water
table).
This
table
includes
only
the
definitions
of
intensities
VII—X
that
are
used
in
the
paper.
38°N
—36°N
km
0
50
100
34`
N
20°E
/2/6
Tr
enc
24°E
e
26°E
2TE
22°E
0
c=a
a
9
Alkyonide
7„,
egra
ence
G
Ms
=5.3)
Pyrgo
1993
5=5
.
/
Ara
Kythica
2006
C
r
etan
Basin'
Mw
ESI
2007
SCALE
IN
GREECE
&
SEISMIC
HAZARD
ASSESSMENT
15
Fig.
1.
Regional
map
showing
the
locations
of
the
studied
earthquakes
within
the
Hellenic
Arc.
The
1981
Alkyonides
earthquake
sequence
and
the
1995
Pyrgos
earthquake
were
shallow
events,
whereas
the
2006
Kythira
event
occurred
on
the
subduction
zone
with
a
focal
depth
of
about
70
km.
Papanikolaou
et
al.
2007),
therefore
the
generation
of
a
Ms
=
5.5
thrust
event
remains
a
question.
Nevertheless,
its
focal
depth
(15
km
as
proposed
by
Stavrakakis
(1996),
but
not
accurately
known)
implies
that
it
could
also
be
related
to
the
subduction
processes
of
the
Hellenic
Trench
that
is
situated
approximately
70
km
to
the
west.
The
subduction
zone
as
imaged
by
Laigle
et
al.
(2002)
dips
at
a
very
low
angle
up
to
the
Greek
mainland
where
at
about
15
km
depth
the
dip
of
the
interplate
reflec-
tor
becomes
steeper,
forming
a
deep
ramp.
The
predominant
stress
field
in
the
offshore
area
around
Zakynthos
and
Western
Peloponnese
has
been regarded
as
compressional
(e.g.
Papazachos
1990)
although
more
recent
studies
show
a
predomi-
nant
dextral
strike
slip
faulting
making
the
situation
even
more
complicated
(e.g.
Kiratzi
&
Louvari
2003;
Roumelioti
et
al.
2004).
Therefore,
it
is
poss-
ible
that
near
the
coast
there
is
an
extensional
regime
over
the
upper
10-12
km,
whereas
at
deeper
depths
there
is
either
a
prevailing
compressional
regime
due
to
the
subducting
plate
(e.g.
Laigle
et
al.
2002)
or
a
dextral
shear
zone
that
may
be
linked
to
the
major
neighbouring
Kefalonia
strike-slip
Makrisia
VI
Agridio
Ladiko
111
V
Anemochori
V1
Krestena
Neo
L
II
adiko
Samiko
1111
V
r
i
na
III
IV
idlvelakia
1
11
Ionian
Sea
Epita
I
io
Chanakia
VI
wo
Aryan
itis
/
I
Vil
IWO
IV
,
I
Ag.G
VII
eorgios
/
AI
pochori
Vounarao
VI
K
a
ra
t
ou
l
as
/
1
1
Ag
ll
lias
-HI
IIT
VII
Abe
lona
s
I
VI
Katakolo
Kardama
III
He
mad
io
Ole
ni
Do
u
ll
r
i
e
ika
Eleonas
III
II
Amaliada
V
Laste
ik
a
am
Ka
i
r
l
outes
irakito
Skouvriochoritym
VIII
La
beti
I
i
Vitmeika
fV1I-
VAS
yro
V
o
I
s
I
MINH
Kari
Skliva
VII
l
I
V
Pe
kr
V
Varvasen
a
(Vf-V11)
lIk
(VII
I
-
II
Vili)
VII
Salmani
trefl
I
VI
vi
VI
Flokas
Spiantza
-""
-----
"
...
. .
...
.
I
i
IV
Olympia
:
.
.e.t
Alfiousa(Vfl-1411)
i
Wilk-
s
r
(Vii)
vI
A
.
1
.
.....
.
•••
1.
Chelidonio
Plata
nos
II
I I
5
km
A
0
2
km
0
0
0
Lasteika
o
00
o
0 0
0
Ionian
Sea
0
-3740'
Pyrgos
00
0
Alfios
river
....
KEY
Faults
Landslides
Ground
fractures
Liquefaction
16
I.
D.
PAPANIKOLAGU
ET
AL.
21
20'
21
30'
Fig.
2.
(a)
The
EMS
1992
(Lekkas
et
al.
2000)
and
the
ESI
2007
scale
(this
study)
distribution
of
the
1993
Pyrgos
earthquake.
The
ESI
2007
values
are
in
bold
italics
in
parentheses.
(b)
Map
of
the
environmental
effects.
Ground
fractures
and
liquefaction
from
Lekkas
(1994)
and
Lekkas
et
al.
(2000);
landslide
localities
from
Koukouvelas
et
al.
(1996).
(a)
fault
(e.g.
Kiratzi
&
Louvari
2003).
The
1993
Pyrgos
foreshock
activity
took
place
on
the
SW
coast,
the
main
shock
under
the
town
of
Pyrgos,
whereas
most
aftershocks
migrated
NE
and
occurred
on
planes
with
a
predominant
NE-SW
direction
(Stavrakakis
1996).
This
probably
exp-
lains
the
large
spatial
distribution
of
reported
sec-
ondary
effects
and
particularly
landslides.
Although
the
town
of
Pyrgos
extends
over
a
rela-
tively
limited
area
of
about
4
km
2
,
the
distribution
ESI
2007
SCALE
IN
GREECE
&
SEISMIC
HAZARD
ASSESSMENT
17
(a)
OX
(b)
Fig.
3.
(a)
View
of
the
damage
inflicted
in
a
traditional
two-storey,
stone
masonry
building.
Several
similar
buildings
suffered
significant
damage
in
the
Pyrgos
event.
(b)
Ground
ruptures
on
paved
road
in
the
city
of
Pyrgos.
of
damage
was
not
uniform
(Bouckovalas
et
al.
1996).
Approximately
25%
of
the
buildings
experi-
enced
severe
damage,
yet
no
foundation
failures
were
identified
(Karantoni
&
Bouckovalas
1997).
The
Pyrgos
event
produced
practically
no
damage
to
modern
reinforced
concrete
buildings
(only
22
buildings
experienced
light
damage),
but
induced
significant
damage
(Fig.
3a)
to
traditional
buildings
of
adobe,
stone
or
brick
masonry
(Karantoni
&
Bouckovalas
1997).
The
intensity
of
seismic
motion
was
affected
not
only
by
the
local
soil
con-
ditions,
but
also
by
the
construction
material,
the
age
and
the
storey
number
of
buildings
(Bouckova-
las
et
al.
1996).
Several
environmental
effects
were
reported
(Fig.
2b).
No
primary
surface
ruptures
were
recorded,
but
ground
fractures
were
observed
at
the
northeastern
part
of
Pyrgos
town
(Fig.
3b)
and
Lasteika
village
(situated
2
km
NW
of
Pyrgos),
cutting
both
paved
roads
and
cultivated
land
(Lekkas
et
al.
2000).
Fractures
were arranged
partly
en
echelon.
Towards
the
NE
part
of
the
town
fractures
were
trending
ENE—WSW,
were
about
30
m
long
and
2-3
cm
wide,
whereas
at
Lasteika
village
fractures
were
trending
east—west
and
NNW—SSE
and
were
up
to
60
m
long
(Lekkas
et
al.
2000).
The
1993
event
triggered
several
landslides,
the
vast
majority
of
which
occurred
along
fault
scarps
and
steep
slopes
and
mostly
in
the
Alfios
southern
river
bank
(Koukouvelas
et
al.
1996).
Koukouvelas
et
al.
(1996)
measured
landslides
at
47
locations
within
an
area
of
145
km
2
.
Significant
liquefaction
and
subsidence
phenomena
were
observed
5
km
SW
of
the
town
of
Pyrgos
in
the
coastal
zone
in
recent
coastal
and
fluvial
deposits
covering
an
area
of
about
5
km
2
(Lekkas
1996).
Soil
fractures
up
to
30
m
long
and
sand
boils
up
to
50
cm
in
diameter
were
observed
(Lekkas
1994).
Finally,
subsidence
was
also
observed
in
alluvial
unconsolidated
deposits
within
Pyrgos.
All
these
environmental
effects
are
depicted
in
Figure
2b
and
have
been
assessed
in
relation
to
the
ESI
2007
scale
(in
Fig.
2a,
values
in
bold
italics
in
parentheses).
According
to
these
effects
the
maximum ESI
2007
values
(VII—VIII)
are
observed
in
the
town
of
Pyrgos
and
Lasteika
village,
where
ground
fractures
a
few
of
tens
of
metres
long
have
been
recorded.
Even
though
landslides
are
scattered
along
a
large
area
(>100
km
2
),
possibly
indicating
a
maximum
intensity
of
VIII,
most
of
them
were
small,
occurred
along
unstable
slopes
and
fault
scarps,
and
clustered
accordingly
in
certain
localities.
Therefore,
we
assign
intensity
values
in
these
sites,
ranging
from
VI
to
VII
—VIII,
depending
on
the
density
of
the
landslides.
Liquefaction
phenomena
were
also
reported
near
the
coast
and
the
Alfios
delta
(soil
fractures
a
Katakolo
5
km
lonfan
Sea
Allot
Ptver
VIII
EMS
(19921
In
VII
EMS
09921
a
ESI
(20071
FT
T1
ESI
(2002)
Fig.
4.
Comparison
of
the
isoseismal
pattern
between
the
EMS
1992
and
the
ESI
2007
intensity
scales.
The
black
triangle
symbols
show
localities
where
an
ESI
2007
intensity
VII—VIII
degree
has
been
assessed.
5
km
18
I.
D.
PAPANIKOLAOU
ET
AL.
few
tens
of
metres
long
and
sand
boils
up
to
50
cm
in
diameter),
a
locality
highly
favourable
for
lique-
faction.
These
characteristics
imply
a
VII
ESI
2007
value.
Maximum
EMS
1992
intensity
VIII
was
recor-
ded
in
the
town
of
Pyrgos
and
Lasteika
village
and
correlated
to
the
areas
where
ground
ruptures
were
observed
and
an
ESI
2007
VII
—VIII
has
been
assigned
(Fig.
2a
and
Fig.
4).
Figure
4
shows
the
isoseismal
pattern
of
the
epicentral
region
based
on
the
ESI
2007
and
the
EMS
1992
scales,
res-
pectively.
The
main
difference
is
traced
along
the
Alfios
river
where
liquefaction
and
sliding
phenom-
ena
occurred
towards
the
west
and
the
east
res-
pectively,
extending
the
ESI
1997
VII
isoseismal
to
the
south.
However,
this
difference
is
mainly
due
to
the
lack
of
EMS
1992
data,
since
no
villages
are
found
in
these
localities
to
record
an
EMS
1992
value.
Overall,
for
the
1993
Pyrgos
event,
the
EMS
1992
and
the
ESI
2007
scales
seem
to
comply
well
not
only
regarding
the
maximum
recorded
epicentral
intensity,
but
also
with
the
entire
iso-
seismal
pattern.
The
1981
Alkyonides
earthquake
sequence
in
the
Corinth
Gulf
On
24,
25
February
and
4
March
1981
three
(Ms
=
6.7,
Ms
=
6.4,
Ms
=
6.3)
successive
destructive
events
(20
fatalities
and
500
injured)
occurred
at
the
eastern
end
of
the
Corinth
Gulf
(Figs
1
and
5)
(Jackson
et
al.
1982;
Papazachos
et
al.
1982;
Taymaz
et
al.
1991).
Hubert
et
al.
(1996)
showed
that
the
last
two
events
of
the
sequence
lie
in
areas
where
a
positive
Coulomb
stress
increase
has
been
calculated,
implying
that
this
earthquake
sequence
was
the
result
of
stress
transfer
that
triggered
the
second
and
third
events.
All
three
events
correspond
to
normal
faulting,
accommodating
north—south
extension.
The
focal
mechanisms
that
described
the
coseismic
slip
at
depth
(c.
10
km),
exhibit
similar
fault
plane
orien-
tations
and
kinematics
to
those
measured
on
the
faults
at
the
surface
(Morewood
&
Roberts
2001).
Damages
occurred
in
three
different
provinces
(Beotia,
Attica
and
Corinth)
where
in
total
7701
buildings
collapsed
or
had
damage
beyond
repair,
KalamaRi
bay
Kapareili
,---•"70
"<
ri
/
20
cm
40
cm.
//
Plataies
0
cm
40
cm
)
9111
100
cm
6.3
4
March
Psatha
Porto
Germeno
24
February
5.7
Perachora
Peninsula
+
+20
cm
+
Alepochori
Vouliagmeni
40
cm
100
cm
60
cm
Lake
- - -
Subsided
coastline
+
-4-
Uplifted
coastline
Primary
surface
ruptures
25
February
6.4
Alkyonides
Gulf
Strava
—80
cm
-loo
cm-
....;-'
Milokopi
Schir2--
-
1755;cm
30
cm
Perachora
.
9,
--
-
30
cm
..
/
20
cm
Pissi:
10
cm
150
cm
Fig.
5.
The
1981
Alkyonides
earthquake
sequence,
eastern
Corinth
Gulf.
View
of
the
epicentral
region
with
emphasis
on
the
primary
surface
ruptures
and
coastal
uplift/subsidence.
Sketch
modified
from
Jackson
et
al.
(1982),
Mariolakos
et
al.
(1982)
and
Hubert
et
al.
(1996).
ESI
2007
SCALE
IN
GREECE
&
SEISMIC
HAZARD
ASSESSMENT
19
x
1
I
-
4
Fig.
6.
(a)
West
of
Alepochori
up
to
the
western
part
of
the
bay
of
Strava,
50-60
cm
of
subsidence
was
observed,
flooding
up
to
50
m
of
the
former
shore
(Mariolakos
et
al.
1982).
(b)
View
of
the
surface
ruptures
on
the
Plataies—Kaparelli
fault
zone
during
the
4
March
event,
producing
50-60
cm
of
throw
(70
cm
of
displacement).
{al
and
20
954
buildings
were
severely
damaged
(Antonaki
et
al.
1988).
These
events
produced
numerous
earthquake
environmental
effects
(EEE)
such
as
rockfalls,
landslides
(both
onshore
and
offshore),
liquefaction,
a
weak
tsunami
wave,
significant
coastal
subsidence
and
uplift,
but
most
importantly
extensive
primary
surface
faulting
(Figs
5
and
6b).
In
particular,
in
the
Pissia
Fault,
surface
ruptures
were
longer
than
10
km
and
dis-
placements
were
in
the
range
of
50-70
cm
with
a
Isoseismal
map
24th
and
251h
February
1981
events
VII
Gull
of
Corinth
Kalamakf
,
VI
Xylo
VIII
jai
Megrim
Athen
Saronic
Gull
°
Corinth
VII
Isoseismal
map
4th
March
1981
even)
Gulf
of
Corinth
Yytoka
k
I
la
m
Loutra.
VII
Saronic
Gull
VII
At
s
Corinth
0
Thal)
Plataio
Vlf
Vlf
Noa
Alkyonides
Gulf
..
l
it
Strava
.
Ilt
,
,
k
,
I
Sch
nos
4anora
,
Pissia„
A
le
pochon
0
5km
\
c„.,.-
‘v
20
I.
D.
PAPANIKOLAOU
ET
AL.
maximum
recorded
value
of
150
cm,
whereas
in
the
Alepochori
Fault
displacement
was
about
100
cm
high
(Jackson
et
al.
1982;
Fig.
5).
The
4
March
event
ruptured
the
Plataie-Kaparelli
Fault
Zone
(c.
10
km
of
surface
ruptures)
producing
an
average
50-60
cm
of
throw
(Jackson
et
al.
1982;
Mariolakos
et
al.
1982;
Figs
5
and
6b)
and
a
maximum
heave
and
throw
of
60
and
120
cm
respectively
between
Kaparelli
and
Plataies
(Papazachos
et
al.
1982).
West
of
Alepochori
up
to
the
western
part
of
the
Bay
of
Strava,
60
cm
of
subsidence
was
observed,
flooding
up
to
50
m
of
the
former
shore
(Mariolakos
et
al.
1982;
Fig.
6a);
however,
east
of
Alepochori
coastal
uplift
was
observed
(Jackson
et
al.
1982;
Vita-Finzi
&
King
1985).
In
Schinos
and
Strava
coastline,
there
was
disagreement
on
the
amount
of
subsidence
recorded,
ranging
from
50-80
cm
(Andronopoulos
et
al.
1982;
Mariolakos
et
al.
1982;
Hubert
et
al.
1996)
up
to
120
and
150
cm
(Khoury
et
al.
1983;
Vita-
Finzi
&
King
1985).
We
use
a
value
of
80
cm
based
on
Hubert
et
al.'s
(1996)
arguments
and
mod-
elling
which
show
that
values
higher
than
100
cm
probably
overestimate
the
coseismic
effect.
Subsidence
of
a
few
centimetres
was
also
repo-
rted
away
from
the
epicentral
areas
in
both
Loutraki
and
Kiato
coastal
area
(Andronopoulos
et
al.
1982;
see
Figs
5
and
7
for
localities).
Extensive
liquefac-
tion
occurred
at
the
Kalamaki
Bay
coastal
area
(Andronopoulos
et
al.
1982)
as
well
as
in
Porto-
Germeno
and
in
Kineta
(Papazachos
et
al.
1982).
Ground
fissures
were
reported
in
Loutraki
beach,
Vouliagmeni
Lake,
Porto
Germeno,
Kiato
and
Corinth
(Papazachos
et
al.
1982).
Submarine
slumping
in
the
Alkyonides
deep
basin
and
several
mass-movement
phenomena
in
the
shelf
area
have
also
been
detected
(Perissoratis
et
al.
1984).
In
particular,
a
large-scale
slump
has
been
documented
about
10
km
long,
1.5-2
km
wide,
extending
16
km2
over
a
depth
of
360
m
(Perissoratis
et
al.
1984).
Jackson
et
al.
(1982)
quoted
that
local
people
reported
a
1
m
high
tsunami
during
the
main
shock
in
the
Alkyonides
Gulf.
Therefore,
it
is
possible
that
the
tsunami
gen-
eration
can
be
attributed
to
the
large-scale
slumping
detected
by
Perissoratis
et
al.
(1984).
All
these
environmental
effects
are
depicted
in
Figure
5
and
have
been
assessed
according
to
the
ESI
2007
scale
(Fig.
8).
It
should
be
noted
that
subsidence
values
reported
by
Vita-Finzi
&
King
(1985)
around
Milokopi
and
southwards
up
to
the
town
of
Loutraki
have
been
debated
(Pirazzoli
et
al.
1994;
Hubert
et
al.
1996)
and
have
not
been
considered
in
this
study.
Moreover,
there
is
some
controversy
as
to
whether
the
ruptures
near
Pissia
and
Schinos
should
be
ascribed
to
the
first
or
the
second
event
(Jackson
et
al.
1982;
King
et
al.
1985;
Taymaz
et
al.
1991;
Abercrombie
et
al.
Fig.
7.
MS
(Mercalli-Sieberg,
a
version
similar
to
the
MCS)
intensity
distribution
of
the
1981
Alkyonides
earthquake
sequence
(Bulletin
of
the
Geodynamic
Institute
of
Athens
1981;
Antonaki
et
al.
1988).
This
earthquake
sequence
had
a
core
of
high
intensities
around
the
epicentral
area
and
a
second
maximum
of
high
intensities
at
70
km
distance,
affecting
several
districts
of
Athens.
On
average,
Athens
experienced
intensities
VII
and
VIII;
however,
in
some
boroughs
and
building
blocks
intensities
up
to
IX
were
also
recorded.
.=
INTENSITY
X
ESI
{2007}
INTENSITY
IX
ESI
(2007)
R7I
INTENSITY
IX
Mercalli-Sleberg
Fig.
8.
Comparison
of
the
isoseismal
pattern
between
the
MS
and
the
ESI
2007
intensity
scales.
ESI
2007
SCALE
IN
GREECE
&
SEISMIC
HAZARD
ASSESSMENT
21
1995;
Hubert
et
al.
1996),
as
both
occurred
at
night
and
only
a
few
hours
apart.
However,
for
our
study
this
makes
no
difference
since
these
two
events
cannot
be
separated
in
terms
of
their
macroseismic
effects.
Following
the
above
descriptions
a
maximum
epicentral
ESI
2007
value
of
X
is
determined
in
several
sites
(Fig.
8)
and
particularly
along
strike
the
primary
surface
ruptures
in
Pissia,
Schinos
and
in
Kaparelli—Plataies
where
they
exceeded
a
few
tens
of
centimetres
in
height.
Intensity
X
has
also
been
allocated
along
the
coastal
zone
from
Strava
up
to
Alepochori,
where
significant
subsi-
dence
ranging
from
a
few
decimetres
up
to
100
cm
has
been
recorded.
Intensity
IX
is
mainly
assigned
in
areas
where
the
surface
ruptures
were
a
few
tens
of
centimetres
high.
Finally,
intensity
VIII
was
widely
assessed
affecting
a
large
area
where
ground
ruptures,
extensive
landslides,
rockfalls
and
liquefaction
phenomena
have
been
observed.
Maximum
MS
(Mercalli
—Sieberg)
intensity
values
(a
version
similar
to
the
MCS)
were
also
recorded
in
all
villages
that
were
in
close
proximity
to
the
activated
faults
(Fig.
8;
Perachora
IX—X,
Plataies
IX—X,
Schinos
IX,
Pissia
IX,
Kaparelli
IX).
However,
no
intensity
X
has
been
assigned
and
most
of
the
epicentral
villages
recorded
an
epicentral
intensity
IX
(Fig.
8).
Figure
8
shows
the
different
isoseismic
patterns
of
the
epicentral
region
based
on
the
ESI
2007
and
the
Mercalli
Sieberg
scales,
respectively.
Differences
are
note-
worthy,
but
not
substantial.
It
should
be
noted
that
surface
geology
played
a
decisive
role
in
the
damage
distribution
and
had
a
significant
effect
on
the
intensity
observed
at
a
site.
On
average,
under
similar
circumstances
sites
located
on
soil
foundations
experienced
about
one
intensity
degree
more
shaking
than
sites
located
on
rock
foundations,
whereas
sites
on
Neogene
sediments
experienced
about
half
a
degree
greater
intensity
than
sites
located
on
rock
foundations
(Tilford
et
al.
1985).
These
shallow
normal
faulting
earthquakes
aff-
ected
not
only
the
Perachora
Peninsula (maximum
intensity
IX—X),
Plataies
(IX
—X)
or
Kaparelli
(IX),
but
also
the
city
of
Athens,
located
70
km
to
the east,
where
tens
of
buildings
collapsed
in
certain
town
districts
(Fig.
7).
As
a
result,
this
earth-
quake
sequence
had
an
anomalous
intensity
distri-
bution
with
a
core
of
high
intensities
around
the
epicentral
area
and
a
second
maximum
of
high
intensities
at
70
km
distance,
affecting
several
dis-
tricts
of
Athens.
On
average,
Athens
experienced
intensities
of
VII
and
VIII;
however,
in
some
bor-
oughs
and
building
blocks,
intensities
up
to
IX
were
also
recorded.
In
particular,
in
Athens
1175
buildings
collapsed
or
had
to
be
demolished
after
the
earthquake,
whereas
7824
buildings
experienced
severe
damage
(Antonaki
et
al.
1988).
The
degree
of
damage
changed
abruptly
over
short
distances
due
to
surface
geology.
In
Athens,
the
area
of
damage
was
highly
localized
in
the
boroughs
of
Chalandri,
Anthoupoli,
Moschato,
Aigaleo,
Nea
Ionia
and
Nikaia
(suburbs
of
Athens)
mainly
due
to
poor
local
site
conditions
(mostly
fluvial
and
alluvial
deposits).
In
particular,
in
the
Chalandri
district
buildings
were
of
good
quality.
The
highest
percen-
tage
of
damage
to
single-and
two-storey
buildings
occurred
where
the
depth
to
bedrock
(less
than
40
m)
and
thickness
of
recent
sediments
(less
than
10
m)
were
minimum,
whereas
for
the
multistorey
buildings
the
higher
damage
occurred
where
the
depth
to
bedrock
was
maximum
(greater
than
40
m)
and
the
thickness
of
recent
deposits
from
5
to
15
m
(Christoulas
et
al.
1985).
Therefore,
damage
to
multistorey
buildings
occurred
because
the
dominant
period
of
the
soil
was
approximately
equal
to
the
dominant
period
of
these
buildings
(Christoulas
et
al.
1985).
The
2006
Kythira
earthquake
On
8
January
2006
a
thrust
faulting
event
M
w
=
6.7
with
considerable
strike-slip
motion
occurred
in
southwestern
Greece
(European
Mediterranean
Seismological
Centre,
unpubl.
data;
Konstantinou
et
al.
2006).
This
event
is
related
to
the
Hellenic
subduction
zone
(Fig.
1)
and
the
epicentre
was
located
a
few
tens
of
kilometres
east
of
the
island
of
Kythira
with
focal
depth
estimated
at
70
km
(United
States
Geological
Survey,
unpubl.
data).
The
event
was
felt
throughout
Greece
and
the
eastern
Mediterranean
in
general
(from
Southern
Italy
and
Dalmatian
coasts,
to
Bulgaria,
Turkey,
Jordan,
Israel
and
Egypt).
No
casualties
were
reported
and
damage
was
restricted
to
the
village
of
Mitata
on
the
island
of
Kythira
(Fig.
9a).
Several
old
stone
masonry
build-
ings
experienced
significant
damage
(including
a
few
collapses;
Fig.
10b);
however, modern
rein-
forced
concrete
buildings
did
not
suffer
any
damage.
The
metropolitan
church
located
in
the
village
square
sustained
severe
damage
(Fig.
10a)
and
several
stone
fences
collapsed.
A
number
of
rockfalls,
landslides
and
fractures
disturbed
the
local
road
network
(Fig.
lib,
c
and
d),
affecting
an
area
of
about
15
km
2
.
However,
they
were
of
limited
size
(Fig.
lid).
Fractures
a
few
meters
long
were
observed
on
paved
roads
within
the
village
(Fig.
11a).
The
biggest
landslide
affected
Mitata
village
square
that
was
partly
detached
(Fig.
lib),
involving
a
collapsing
volume
of
about
5000
m
3
(Fig.
12;
Lekkas
&
Danamos
2006).
Several
masses
of
rock
(c.
500
m
3
each)
were
deta-
ched
for
about
100
m
and
were
accumulated
at
the
base
of
the
slope
on
the
Mitata—Viaradika
road.
A
few
more
rockfalls
were
observed
along
the
KEY
Pliocene
coann,adirnenit
r,=1
1-P1e
MkKeolc
ocooksenerates
urresionesand
%ash
rim
,.
Una
lirmitoaars
and
Hsrach
halo
Ilnat
ME
,..
"7,:=
1
'
Von
Noss
-
lonom
ra
-
uk
NE
I.
D.
PAPANIKOLAOU
ET
AL.
22
(a)
Potamco_
(b)
SW
s.
1km
Fig.
9.
(a)
Geological
map
of
Kythira
island
(modified
from
Papanikolaou
&
Danamos
1991).
(b)
Cross-section
across
Mitata
village.
Mitata
village
is
situated
on
the
immediate
hanging
wall
of
an
active
fault.
In
addition,
it
is
founded
on
Pliocene
marine
sediments
that
rest
on
a
large
NNW—SSE
trending
detachment
fault
that
lies
a
few
hundred
metres
below
the
village
separating
the
non-metamorphic
rocks
from
the
underlying
metamorphic
rocks
of
the
Arna
Unit.
remaining
road
network
of
the
island,
but
no
lique-
faction
phenomena
were
recorded.
Therefore,
remarkable
EEE
were
observed
only
in
the
village
of
Mitata
in
compliance
with
the
damage
distri-
bution.
It
is
interesting
to
note
that
even
though
several
villages
of
the
island
are
equidistant
from
the
epicentre,
only
Mitata
village
was
damaged
and
experienced
some
noteworthy
EEE.
In
particu-
lar,
in
Potamos
village,
situated
only
35
km
from
the
epicentre
(Fig.
9a),
the
reported
MM
intensity
was
V+,
whereas
in
Mitata
village
situated
c.
40
km
the
intensity
was
VII+
(Konstantinou
et
al.
2006).
This
intensity
distribution
was
likely
due
to:
(a)
the
poor
foundation
conditions
of
the
village,
(b)
its
proximity
to
an
active
neotectonic
fault
that
bounds
a
Late
Miocene—Pliocene
basin
(Papanikolaou
&
Danamos
1991),
and
(c)
the
presence
of
a
large
detachment
fault
at
a
few
hundred
metres
below
the
village
(Papanikolaou
&
Danamos
1991).
On
the
other
hand,
Potamos
village
is
founded
on
the
metamorphic
rocks
of
the
Arna
Unit
and
consequently
is
located
under
the
footwall
block
of
the
detachment
(Fig.
9).
The
NE—SW
trending
cross-section
across
Mitata
village
(Fig.
9b)
shows
the
geological
struc-
ture
of
the
area.
The
village
of
Mitata
is
founded
on
Pliocene
marine
sediments
that
rest
on
a
large
NNW—SSE
trending
detachment
fault.
This
detach-
ment,
situated
a
few
hundred
metres
below
the
village,
separates
the
non-metamorphic
rocks
from
the
underlying
metamorphic
rocks
of
the
Arna
Unit,
belonging
to
the
East
Peloponnesus
detach-
ment
system
(Papanikolaou
&
Royden
2007).
Finally,
the
village
of
Mitata
is
situated
in
the
immediate
hanging
wall
of
an
active
NW
—SE
normal
fault.
The
village
of
Mitata
was
devastated
(intensity
XI)
by
a
similar
deep-sourced
(c.
80
km),
but
significantly
stronger
M
=
7.9
event
that
occurred
in
1903
(Papazachos
&
Papazachou
1997).
Then,
the
newly
constructed
church
and
the
school
building
collapsed
and
several
ground
fis-
sures
were
reported,
of
which
one
was
200
m
long
and
1
cm
wide
(Papazachos
&
Papazachou
1997).
This
past
event
also
confirms
that
Mitata
village
is
founded
in
unfavourable
geological
conditions.
Based
on
the
environmental
effects,
an
ESI
2007
maximum
epicentral
intensity
of
VII
—VIII
has
been
assigned,
which
is
similar
to
the
MM
reported
intensity
value.
Discussion:
advances
and
limitations
of
the
ESI
2007
scale
The
ESI
2007
scale
has
been
tested
in
earthquakes
that:
(i)
had
different
source
characteristics
(magnitude,
focal
mechanism
and
focal
depth)
and
(ii)
produced
a
variety
of
environmental
effects
(primary
surface
faulting,
minor
and
major
second-
ary
effects),
which
help
us
obtain
a
spherical
view
of
its
performance.
The
ESI
2007
scale
has
been
easily
applied,
leaving
no
question
marks
or
'grey'
areas
in
all
three
examples.
Above
the
intensity
VII
degree
when
environmental
effects
become
prominent,
the
ESI
2007
scale
can
define
the
intensity
degree
with
a
high
level
of
accuracy
as
also
shown
in
several
recent
and
historic
earthquakes
worldwide
(e.g.
Serva
et
al.
2007;
Tatevosian
et
al.
2007).
Overall,
the
1993
Pyrgos
and
the
2006
Kythira
events
demonstrate
that
for
moderate
intensity
levels
(VII
and
VIII)
the
ESI
2007
and
the
tra-
ditional
scales
compare
fairly
well.
On
the
other
hand,
the
1981
Alkyonides
earthquake
sequence
demonstrates
that
there
is
inconsistency
between
ESI
2007
and
traditional
scales
for
the
high
intensity
values
(IX,
X).
This
seems
to
agree
with
similar
examples
worldwide,
emphasizing
the
importance
and
the
increasing
accuracy
of
the
ESI
2007
ESI
2007
SCALE
IN
GREECE
&
SEISMIC
HAZARD
ASSESSMENT
23
(a)
T
(b)
Fig.
10.
(a)
Photos
of
the
damage
inflicted
on
the
metropolitan
church
of
Mitata
village.
The
church,
located
in
the
village
square,
is
constructed
of
porous
limestone
blocks
cemented
with
lime
wash
without
concrete
columns
and
experienced
significant
damage.
Severe
damage
was
also
inflicted
at
both
bell
towers.
(b)
A
few
collapses
of
old
plain
stone
masonry
buildings
were
recorded
at
Mitata.
scale
towards
the
highest
levels
of
the
scale
in
the
epicentral
area
(e.g.
Michetti
et
al.
2007;
Serva
et
al.
2007).
In
particular,
for
the
1993
Pyrgos
event,
the
EMS
1992
and
the
ESI
2007
scales
seem
to
comply
well
regarding
not
only
the
maximum
recorded
epicen-
tral
intensity,
but
also
with
the
overall
isoseismal
pattern.
Nevertheless,
it
should
be
mentioned
that
no
villages
were
founded
near
the
landslide
or
the
liquefaction-prone
areas,
otherwise
it
is
possible
that
the
traditional
intensities
would
have
recorded
a
higher
epicentral
intensity
value.
In
addition,
even
for
the
2006
Kythira
deep-
sourced
event,
the
ESI
2007
and
the
traditional
macroseismic
scales
correlate
well,
suggesting
a
maximum
VII—VIII
intensity.
A
question
arises
as
to
whether
a
more
destructive
deep-sourced
event
such
as
the
M
=
7.9
earthquake
that
occurred
in
Kythira
in
1903
(I
0
=
XI;
Papazachos
&
Papazachou
1997)
would
have
been
correctly
interpreted
in
the
ESI
2007
scale,
since
no
primary
surface
ruptures
would
have
been
observed
to
imply
a
higher
intensity
value
and
reported
ground
fissures
were
of
limited
length.
In
such
deep
not
`linear
morphogenic
events'
(e.g.
Caputo
2005),
where
ruptures
cannot
reach
the
surface,
the
ESI
2007
intensity
level
should
be
correlated
with
the
area
where
severe
environmental
effects
have
been
recorded.
However,
in
such
cases
uncertainties
are
expected
to
be
higher,
implying
that
the
assessment
[d
1
24
I.
D.
PAPANIKOLAOU
ET
AL
(a)
(C)
our'
t
w
(b
)
4
.
4,4
.o"dtjo
.
4
#0,
Fig.
11.
(a)
Ground
ruptures
on
paved
road
at
the
village
of
Mitata.
(b)
View
of
the
landslide
that
affected
Mitata
village
square,
which
was
partly
detached,
involving
a
collapsed
volume
of
about
5000
m
3
.
(c)
View
of
rockfalls
disturbing
the
road.
(d)
View
of
a
minor
landslide
blocking
the
road.
of
the
ESI
2007
scale
should
probably
be
considered
less
precise
for
deep
events.
In
the
1981
Alkyonides
example,
the
ESI
2007
intensity
scale
provides
not
only
a
slightly
higher
maximum
epicentral
intensity
(X),
but
also
a
differ-
ent
spatial
distribution
of
the
isoseismals,
com-
pared
to
the
traditional
scales.
This
implies
that
current
traditional
scales
possibly
underestimate
the
'strength'
of
this
kind
of
earthquake
sequence.
This
occurs
partly
because
the
epicentral
area,
where
significant
EEE
were
recorded,
was
relatively
sparsely
populated.
Indeed,
only
the
small
villages
of
Schinos,
Pissia
Kaparelli
and
Plataies
were
situ-
ated
a
few
hundred
metres
up
to
a
few
kilometres
7,,i
rrr
r
a
yC
KAA
/4
-
f
-r
Church
(see
Fig.10a)
•••'
C9-
ESI
2007
SCALE
IN
GREECE
&
SEISMIC
HAZARD
ASSESSMENT
25
0
)"'"
Fig.
12.
Landslide
(grey
areas)
and
damage
(bold
blocks)
distribution
around
Mitata
village
mapped
at
a
1:5000
scale
(Lekkas
&
Danamos
2006).
Thick
contours
represent
intervals
of
20
m
and
thin
contours
intervals
of
4
m.
away
from
the
localities
where
significant
offsets
(>20
cm)
have
been
observed.
Although
Kaparelli
was
the
most
proximal
village
to
the
surface
rup-
tures
of
the
third
event
and
is
founded
on
a
rather
unfavourable
geological
site
(Pleistocene
fluvial,
breccia
and
slope
deposits),
it
experienced
intensity
IX.
This
occurred
because
it
is
situated
in
the
immediate
footwall
of
the
fault
and
thus
experi-
enced
less
shaking.
Moreover,
in
Schinos village
several
houses
were
founded
on
the
ophiolitic
bedrock
and
experienced
minor
to
moderate
damages
(Andronopoulos
et
al.
1982),
thus
lower-
ing
the
epicentral
maximum
intensity.
The
same
is
probably
true
for
Pissia
since
part
of
the
village
is
founded
on
Holocene
scree
and
Pleistocene
breccia
deposits,
but
the
remaining
part
is
on
the
Alpine
basement.
In
addition,
Plataies
village
is
also
founded
on
Mesozoic
limestones.
Tilford
et
al.
(1985),
following
a
survey
in
the
area,
sugg-
ested
that
surface
geology
significantly
influenced
the
damage
distribution
and
calculated
that
on
average,
buildings
located
on
soil
foundations
experienced
about
one
degree
of
intensity
more
than
those
located
on
rock
foundations.
Previous
remarks
may
explain
why
an
epicentral
intensity
of
X
has
not
been
fully
implemented.
From
this
perspective,
it
is
argued
that
for
the
Alkyonides
example
the
ESI
2007
scale
is
probably
more
appro-
priate
for
drawing
isoseismals
of
intensity
IX
and
X
in
the
epicentral
area.
As
far
as
the
far
field
effects
are
concerned,
there
is
an
inconsistency
for
the
town
of
Athens
between
the
EEE,
which
were
negligible,
and
the
significant
damage
that
occurred
in
some
town
districts.
This
inconsistency
for
the
far
field
of
the
1981
earthquake
sequence
between
the
ESI
2007
and
the
Mercalli
intensity
scale
can
be
attributed
to
several
reasons.
It
could
be
that
intensive
earthquake
environmental
related
effects
have
not
been
expressed
or
even
recorded
in
Athens,
due
to
the
strictly
localized
area
of
damage
and
its
limited
geographical
cover-
age.
However,
it
is
argued
that
this
inconsistency
is
probably
due
to
the
structural
response
of
multi-
storey
buildings,
the bedrock
geology
and
the
local
site
effects
(e.g.
Tilford
et
al.
1985)
in
accord-
ance
with
the
long
distance
from
the
epicentre.
In
this
case
there
was
a
long
period
resonance
because
the
dominant
period
of
the
soil
was
approxi-
mately
equal
to
the
dominant
period
of
certain
buildings,
causing
severe
damage
(e.g.
Christoulas
26
I.
D.
PAPANIKOLAOU
ET
AL.
et
al.
1985).
In
addition,
considering
that
Athens
experienced
three
strong
successive
events
over
a
few
days,
the
weakness
and
the
vulnerability
of
the
buildings
would
have
been
substantially
incre-
ased.
This
comparison
for
the
far
field
effects
may
be
inappropriate
since
no
EEE
were
recorded
in
the
far
field,
even
though
structural
damage
did
occur.
However,
it
is
also
important
to
establish
that
the
ESI
2007
scale
should
be
used
predomi-
nantly
in
the
epicentral
area
and
thus
may
not
accurately
describe
damage
in
the
far
field.
Never-
theless,
the
Kythira
example
shows
that
the
far
field
effects
are
in
compliance
with
the
EEE.
A
few
other
events
have
been
studied
in
Greece
and
reassessed
in
terms
of
the
ESI
2007
scale.
Papathanasiou
&
Pavlides
(2007)
found
that
in
the
2003
Lefkada
earthquake
(Ms
=
6.4),
the
traditional
intensities
tend
to
underestimate
the
ground
shaking
because
the
strengthening
of
buildings,
due
to
the
strict
seismic
code
in
the
area,
resulted
in
better
per-
formance
under
ground
shaking.
However,
two
similar
events
that
occurred
in
the
past
before
the
provision
of
the
seismic
code
had
similar
intensity
values
as
the
ESI
2007
scale.
The
1988
Elia
earthquake
(Ms
=
5.9)
in
NW
Peloponnese
shows
that
the
traditional
intensities
were
similar
to
the
ESI
2007
scale,
whereas
in
the
1999
Athens
event
(Ms
=
5.9),
the
ESI
2007
intensities
under-
estimated
the
impact
of
the
earthquake
(Fokaefs
&
Papadopoulos
2007).
The
2003
Lefkada
(Papathanasiou
&
Pavlides
2007),
the
1999
Athens
(Fokaefs
&
Papadopoulos
2007)
and
the
1981
earth-
quake
sequence
(this
study)
indicate
that
when
the
ESI
2007
and
the
traditional
intensity
scales
dis-
agree,
the
intensity
has
to
coincide
with
the
highest
value
between
these
two
independent
estimates
(see
also
Serva
et
al.
2007;
Michetti
et
al.
2007).
Another
important
issue
that
has
arisen
from
the
1981
Alkyonides
earthquake
sequence
is
the
differ-
ent
isoseismal
distributions
recorded
by
several
rese-
arch
groups.
In
several
epicentral
villages,
reported
intensity values
differ
from
half
(e.g.
Perachora
and
Pissia)
up
to
one
degree
(Schinos).
For
example,
in
Schinos
village
intensity
recordings
varied
from
VIII
—IX
(Papazachos
et
al.
1982),
IX
(Bulletin
of
the
Geodynamic
Institute
of
Athens
1981)
up
to
IX—
X
(Andronopoulos
et
al.
1982),
pro-
viding
a
rather confusing pattern.
This
difference
can
be
attributed
to
several
causes.
It
may
be:
(i)
due
to
the
subjective
interpretation
of
damages
or
(ii)
due
to
the
subjectivity
in
allocating
the
predominant
damage
in
a
site,
or
(iii)
because
the
assigned
inten-
sities
correspond
to
the
maximum
observed
intensity
rather
than
the
mean.
From
this
perspective,
the
ESI
2007
scale
is
probably
easier
to
implement
and
more
precise
in
quantifying
macroseismic
effects,
offering
a
higher
objectivity
in
the
process
of
assigning
intensity
values.
Finally,
the
use
of
many
different
intensity
scales
worldwide
(e.g.
MM,
MCS,
MSK,
JMA),
which
are
also
constantly
updated
(e.g.
EMS
1992)
indirectly
demonstrates
the
inefficiency
of
current
earthquake
intensity
scales
in
describing
the
macroseismic
earthquake
effects.
The
ESI
2007
scale
and
implications
for
seismic
hazard
assessment
Intensity
is
an
important
seismic
hazard
parameter.
The
isoseismal
maps
are
used
to
derive
empirical
relations
for
the
decrease
of
intensity
with
distance,
which
then
are
incorporated
into
the
attenuation
laws
and
used
to
assess
the
seismic
hazard.
One
fundamental
question
that
will
be
posed
is
why
introduce
another
intensity
scale
without
clear
out-
comes
to
the
seismic
hazard
assessment?
In
this
section
we
show
how
the
ESI
2007
scale
could
prove
beneficial
for
seismic
hazard
assessment
by
reducing
the
uncertainty
in
the
empirically
based
attenuation
laws
and
demonstrate:
(i)
how
large
the
uncertainty
is
and
(ii)
how
significant
is
this
uncertainty
for
the
seismic
hazard
maps.
Intensity
attenuates
with
increasing
distance
from
the
earthquake
source,
at
first
rapidly
and
then
more
slowly.
Therefore,
in
order
to
define
the
seismic
hazard
at
a
given
site,
it
is
necessary
to
know
the
expected
attenuation
of
intensity
with
epi-
central
distance.
Thus,
attenuation
curves
are
simple
empirical
relationships
that
give
the
largest
ampli-
tudes
as
a
function
of
epicentral
intensity
and/or
earthquake
magnitude
with
distance
and
are
com-
piled
based
on
the
statistical
elaboration
of
historical
and
instrumental
data.
However,
there
is
a
large
variation
in
the
data,
which
adds
uncertainty
in
the
seismic
hazard
assessment.
This
variation
is
nicely
portrayed
in
an
empirical
magnitude—intensity
data-
base
compiled
by
D'Amico
et
al.
(1999),
which
is
presented
in
Table
2.
This
database
is
extracted
from
instrumental
catalogues
ranging
from
1880
to
1980,
covering
the
whole
Mediterranean
region.
For
example,
Table
2
shows
that
epicentral
intensity
X
has
been
produced
by
significantly
different
magnitude
events,
ranging
from
M
=
6.0
to
M
=
7.0.
It
is
possible
that
a
portion
of
this
variation
in
the
data
stems
from
the
way
macroseismic
effects
have
been
assessed.
Therefore,
wherever
feasible,
by
reconstructing
the
macroseismic
field
of
historical
earthquakes,
through
the
use
of
the
ESI
2007
scale,
the
uncertainties
may
be
signifi-
cantly
reduced.
Evidently,
apart
from
the
attenuation/amplifica-
tion
relationships,
uncertainty
in
seismic
hazard
assessment
stems
from
several
other
factors
such
as
the
fault
geometry,
slip
rates,
the
earthquake
occurrence
model
used
etc.
However,
it
seems
that
(a)
0-
>-
0
1
0
}-
H
0
(
7
)
2-
ESI
2007
SCALE
IN
GREECE
&
SEISMIC
HAZARD
ASSESSMENT
27
Table
2.
Distribution
of
the
magnitude
values
for
each
intensity
class
in
the
Mediterranean
region
Intensity
Number
of
events
Lower
magnitude
Upper
magnitude
Mean
magnitude
(Ms)
VDT
IX
IX
—X
X
161
20
53
5
18
5.0
5.7
5.8
6.3
6.0
5.9
6.3
6.7
6.9
7.0
5.4
6.0
6.2
6.5
6.6
Modified
from
D'Amico
et
al.
1999
seismic
hazard
maps
are
also
highly
sensitive
to
the
attenuation
relationship
used.
In
particular,
in
some
cases
uncertainty
is
large
enough
so
that
it
oversha-
dows
the
other
factors.
For
example,
following
Table
2
on
average
a
M
=
6.5
earthquake
is
exp-
ected
to
produce
an
epicentral
intensity
IX
or
X
(or
IX
—X).
However,
the
exact
value
of
the
epicen-
tral
intensity
(whether
IX
or
X)
is
crucial
for
the
determination
and
modelling
of
the
area
affected
around
the
epicentre
and
the
attenuation
rela-
tionships.
Indeed,
historical
data
of
macroseismic
intensity versus
epicentral
distance
published
by
Grandori
et
al.
(1991),
covering
the
whole
of
the
Apennines
in
Italy,
show
that
earthquakes
with
epi-
central
intensity
IX
=
9)
have
a
mean
radius
of
6-7
km
for
the
intensity
IX
isoseismal,
whereas
earthquakes
with
epicentral
intensity
X
(l
o
=
10)
have
a
mean
radius
of
20
—21
km
for
the
isoseismal
IX
(Fig.
13a).
Similar
values
have
been
reported
for
other
regions
such
as
the
Sino-Korean
craton
(Lee
&
Kim
2002;
Fig.
13b).
The
significance
of
this
uncer-
tainty
can
be
portrayed
and
easily
assessed
in
quan-
titative
fault-specific
seismic
hazard
maps
from
geological
fault
slip-rate
data
(Papanikolaou
2003;
Roberts
et
al.
2004).
Roberts
et
al.
(2004)
used
in
Lazio-Abruzzo,
central
Italy,
an
average
value
of
12.5
km
radius
for
the
modelled
isoseimal
IX
in
the
central
Appenines,
whereas
Papanikolaou
(2003)
used
the
average
value
of
12.5
km
and
an
extreme
upper
value
of
20
km,
running
a
sensitivity
analysis
for
the
southern
Apennines.
Sensitivity
analysis
showed
that
the
error
introduced
by
the
implied
uncertainty
in
the
dimensions
of
modelled
isoseismals
is
significantly
larger
than
the
fault
throw-rate
error
(of
±20%).
This
is
remarkable
because
it
shows
that
input
parameters
such
as
the
isoseismal
dimensions,
which
themselves
are
derived
from
attenuation
relationships,
influence
the
results
more
significantly
than
the
uncertainty
implied
from
the
fault
throw-rate
data
which
govern
the
earthquake
recurrence.
Therefore,
further
evaluation
that
could
constrain
the
isoseis-
mal
dimensions
and
the
attenuation
relationships
will
prove
beneficial
in
limiting
the
uncertainties
implied
in
the
seismic
hazard
analysis
for
the
regions
of
central
and
southern
Apennines.
It
should
be
noted
that
the
complication
and
uncertainty
in
earthquake
ground
motion
and
con-
sequently
in
the
attenuation/amplification
rela-
tionships
is
not
only
related
to
the
way
intensity
values
have
been
assigned
and
isoseismal
lines
lo
=8
l
o
=
9
(:)
1
0
=
10
Intensity
IX
radius
with
max
epicentral
intensity
X
(l
o
=
10)
10
50
Distance
(km)
(b)
0—
l
o
=
8
l
o
=
9
(a
1
0
=
10
1
0
=
8
l
o
=
9
1
0
=
10
10
50
Distance
(km)
Fig.
13.
Attenuation
laws
for:
(a)
the
Apennines
in
Italy
(modified
from
Grandori
et
a/.
1991)
and
(b)
the
Sino-Korean
peninsula
(modified
from
Lee
&
Kim
2002).
Attenuation
laws
are
derived
from
the
statistical
elaboration
of
historical
and
instrumental
data.
The
Apennines
example
shows
that
earthquakes
with
epicentral
intensity
IX
(l
o
=
9)
have
a
mean
radius
of
6-7
km
for
the
intensity
IX
isoseismal,
whereas
earthquakes
with
epicentral
intensity
X
(l
o
=
10)
have
a
mean
radius
of
20-21
km
for
the
isoseismal
IX.
z
L1.1
IX
intensity
radius
3
-
with
max
epicentral
intensity
IX
(1
0
=
9)
28
I.
D.
PAPANIKOLAOU
ET
AL.
have
been
drawn,
but
emerges
from
several
factors,
which
are
critical
but
not
accurately
known.
These
factors
vary
from
source
to
source,
path
to
path
and
from
site
to
site
introducing
a
large
scatter
in
numerical
values
of
ground
motion
(e.g.
Hu
et
al.
1996).
Moreover,
some
of
these
factors
are
'highly
interdependent'
making
it
difficult
to
separate
near-
surface
effects
from
deeper
basin
effects
(Field
et
al.
2000).
Studies
on
the
prediction
of
ground
motion
and
the
site
effects
suggest
that
site
response
has
a
large
intrinsic
variability
with
respect
to
source
location
(Hartzell
et
al.
1997).
The
intrinsic
variabil-
ity
is
caused
by
basin-edge
induced
surface
waves,
focusing
and
defocusing
effects
and
scattering
in
general
that
cannot
be
reduced
in
any
model
(Field
et
al.
2000).
Therefore,
there
is
little
hope
that
all
uncertainties
implied
by
the
attenuation/amplifica-
tion
relationship
can
be
fully
reduced. However,
it
is
also
probable
that
part
of
this
uncertainty
stems
from
the
intensity
evaluation.
The
ESI
2007
scale
offers
higher
objectivity
in
the
process
of
assessing
macroseismic
intensities
than
traditional
intensity
scales
that
are
influenced
by
human
parameters.
Thus,
the
ESI
2007
scale
can
compare
not
only
events
from
different
settings,
but
also
contempor-
ary
and
future
earthquakes
with
historical
and
even
pre-historical
events.
This
occurs
because
the
ESI
2007
scale
follows
the
same
criteria/environ-
mental
effects
for
all
events
that
are
independent
of
the
local
economy
and
cultural
setting
through
time.
Therefore,
a
reappraisal
of
historical
earth-
quakes
so
as
to
constrain
the
INQUA
intensity
scale
may
prove
beneficial
for
the
seismic
hazard
assessment
by
reducing
the
uncertainty
implied
in
the
attenuation
laws.
Conclusions
The
ESI
2007
scale
incorporates
the
advances
and
achievements
of
palaeoseismology
and
earthquake
geology,
forming
an
objective
and
easily
applied
tool
for
measuring
the
earthquake
strength,
particu-
larly
in
the
epicentral
area.
The
ESI
2007
intensity
values
and
the
spatial
dis-
tribution
of
the
isoseismals
for
the
1993
Pyrgos
and
the
2006
Kythira
events
are
similar
to
those
result-
ing
from
the
traditional
scales,
demonstrating
that
for
moderate
intensity
levels
(VII
and
VIII)
the
ESI
2007
and
the
traditional
scales
compare
fairly
well.
On
the
other
hand,
the
1981
Alkyonides
earth-
quake
sequence
shows
that
there
is
an
inconsistency
between
the
ESI
2007
and
the
traditional
scales
both
in
the
epicentral
area,
where
higher
ESI
2007
values
have
been
assigned,
and
for
the
far
field
effects.
In
the
1981
Alkyonides
sequence,
the
ESI
2007
scale
provides
not
only
a
slightly
higher
maximum
epi-
central
intensity,
but
also
a
different
isoseismal
pattern
compared
to
the
traditional
scales,
implying
that
current
traditional
scales
underestimate
the
`strength'
of
this
earthquake
sequence.
This
occurs
partly
because
the
epicentral
area,
where
significant
EEE
were
recorded,
was
sparsely
populated.
In
addition,
several
villages
located
in
the
epicentral
region
were
founded
on
bedrock
sites
and
others
on
the
footwall
block,
experiencing
less
shaking.
The
1981
earthquake
sequence
emphasizes
the
importance
and
the
increasing
accuracy
of
the
ESI
2007
scale
towards
the
highest
levels
of
the
scale
in
the
epicentral
area.
In
contrast,
the
ESI
2007
scale
may
not
accurately
describe
the
damage
in
the
far
field.
In
Athens,
situated
about
70
km
from
the
epicentre,
the
EEE
were
negligible,
but
several
town
districts
suffered
significant
damage,
because
the
dominant
period
of
the
soil
was
approximately
equal
to
the
dominant
period
of
certain
buildings.
This
example
demonstrates
once
again
that
when
the
ESI
2007
and
the
traditional
intensity
scales
dis-
agree,
the
intensity
has
to
coincide
with
the
highest
value
between
these
two
independent
estimates.
Earthquake
environmental
effects
provide
higher
objectivity
in
the
process
of
assigning
intensity
values,
so
that
the
ESI
2007
scale
is
the
best
tool
to
compare
recent,
historic
and
pre-historic
earth-
quakes
as
well
as
earthquakes
from
different
tectonic
settings.
A
reappraisal
of
historical
earthquakes,
so
as
to constrain
the
ESI
2007
scale,
may
prove
ben-
eficial
for
the
seismic
hazard
assessment
by
redu-
cing
the
uncertainty
implied
in
the
attenuation
laws.
We
thank
Alessandro
Michetti
for
discussions
concerning
the
application
of
the
ESI
2007
scale.
Reviews
from
Spyros
Pavlides
and
Riccardo
Caputo
improved
the
paper.
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