1. ASSESSMENT ANALYSIS OF SEISMOLOGIC RISK
AND GEOHAZARD VULNERABILITY OF FIRST LEVEL
IN MAJOR CULTURAL HERITAGE SITES OF ALBANIA
Gian Paolo Cavinato (*), Llambro Duni (**), Massimiliano Moscatelli (*), Iris Pojani (**),
Maurizio Simionato (*), Giuseppe Cosentino (*), Alessandro Pagliaroli (*)
(*) CNR- Istituto di Geologia Ambientale e Geoingegneria, Rome, Italy
(**) University of Tirana, Albania
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites Berat, 8th May 2012

2. ASSESSMENT ANALYSIS OF SEISMOLOGIC RISK
AND GEOHAZARD VULNERABILITY OF FIRST LEVEL IN
MAJOR CULTURAL HERITAGE SITES OF ALBANIA
Contributions
• Historical and archaeological assessment (Iris Pojani)
• Regional seismic hazard assessment (Llambro Duni)
• Local seismic hazard assessment (CNR-IGAG work group)
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

3. Risk preparedness in CH sites
Risk = Hazard x Elements at risk x Vulnerability
from Managing Disaster Risks (UNESCO 2010)
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

4. Risk preparedness in CH sites
from Managing Disaster Risks (UNESCO 2010)
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

5. from Managing
Disaster Risks
(UNESCO 2010)
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

6. Seismic hazard - Foreword
• Surface effects due to an earthquake propagation are related to several physical
phenomena, that can be summarized in three groups as: 1) source mechanism; 2)
propagation of seismic waves; 3) site effects.
• When seismic waves propagate from a source, their amplitudes, frequencies, and
durations are modified due to local conditions. These “modifications” are globally
defined as site effects or local seismic response.
• Modifications of the seismic input for a specific site are defined in comparison to a
seismic bedrock, where the seismic signal is assumed to be unmodified. This seismic
bedrock is generally located below the ground surface and underlies the covering
geological formations inducing site effects.
• Seismic response can be defined for several sites and a map grouping zones whit
homogeneous site effects can be produced: this is the seismic microzonation.
• Seismic microzonation in urban areas is a tool suitable for planners and decision
makers. Moreover, the seismic action calculated for significant monuments is useful
for consolidation works.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

7. REGIONAL
SEISIMC HAZARD
IN ALBANIA
Albania is
characterized
from an
intensive
seismic
microactivity
(1.0<M≤3.0),
from many
small
earthquakes
(3.0<M≤5.0),
from rare
medium-sized
earthquakes
(5.0<M≤ 7), and
very seldom
from strong
earthquakes
(M>7.0).
CH sites
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

8. Seismic microzonation
LOCAL
SEISIMC HAZARD The seismic microzonation studies are aimed at streamlining the
EVALUATION knowledge of local seismic hazard, returning useful information for:
When seismic • guiding the choice of areas for new settlements;
waves • planning investigations and levels of detail;
propagate from
a source, their • establishing guidelines and criteria of interventions in urban areas and
amplitudes, CH sites.
frequencies,
and durations • defining priorities for interventions.
are modified In retrofitting of existing infrastructures or monuments, seismic
due to local
conditions. microzonation studies highlight the importance of phenomena such as
These possible amplification of shaking and permanent deformation.
“modifications”
are globally Following the Italian "Addresses and Criteria for Seismic Microzonation"
defined as site (ICMS, 2008), the levels of analysis for studies of seismic microzonation
effects or local
seismic increase in complexity and effort going from level 1 to level 3:
response. • level 1 is an introductory level designed to divide the territory into
seismic microzones qualitatively “homogeneous” in seismic
perspective;
• levels 2 and 3 produces a quantitative map of seismic microzonation,
by means of numerical simulations.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

9. Seismic microzonation of level 1
LOCAL
SEISIMC HAZARD How is created?
EVALUATION
The input information can be summarized as follow:
When seismic 1) topographic (e.g., maps and Digital Terrain Models) and
waves
propagate from
geomorphological (e.g., escarpments and landslides) information ;
a source, their 2) geological maps with information on litho-type, i.e., “different kinds of
amplitudes,
frequencies,
rocks or terrains”;
and durations 3) already available geological, geotechnical, and geophysical
are modified
due to local
information from boreholes and other in situ tests;
conditions. 4) thickness of soft geological formations covering the seismic bedrock;
These
“modifications”
5) evaluation of the seismic bedrock depth from noise measurements.
are globally
defined as site
effects or local
What is on the map?
seismic
response.
• Stable zones, where significant local effects of any nature are unlikely.
• Stable zones susceptible to local amplifications, where intensifications
of ground motion are likely.
• Zones susceptible to geological instability, in which the predominant
and expected seismic effects are due to permanent deformations.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

10. GEOLOGICAL
SURVEY FOR
LEVEL 1 SEISMIC
MICROZONATION
Different
lithotypes
behave in
different ways
when interested
by a seismic
wave: they have
to be carefully
mapped.
Zones
susceptible of
permanent
deformations in
seismic
conditions (i.e.,
landslide prone
areas) have also
to be mapped. Apollonia
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

11. NEW
GEOPHYSICAL
SURVEY FOR
LEVEL 1 SEISMIC
MICROZONATION
Microtremor
measurements
performed to
define site the f0=Vs/4H Apollonia
fundamental THE MONASTERY
frequencies,
i.e., soil
resonance
frequencies
when affected
by an
earthquake
event.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

12. 700 m/s
NEW
GEOPHYSICAL
SURVEY FOR
LEVEL 1 SEISMIC
Apollonia
MICROZONATION
THE MONASTERY
MASW enable
to characterize
the velocity
structure of the
subsoil. The
lower the shear
velocity Vs, the
poorer the
«quality» of the
soil in terms of
site response.
The higher the
velocity
contrast
between
superimposed
layers of soils,
the higher the
susceptibility to
local seismic
amplification.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

13. SUSCEPTIBILITY
TO INSTABILITY
Define zones crowns
susceptible to
geological
instability, i.e.,
slope instability,
differential
settlement,
liquefaction, in Apollonia
which the
predominant and
THE THEATRE
expected seismic
effects are due to
permanent
deformations
(amplification of
ground motion is earth flow
also possible).
accumulation
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

14. SEISMIC
MICROZONATION
OF LEVEL 1 OF
APOLLONIA
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

15. What is critical?
SEISMIC
MICROZONATION The seismic microzonation level 1 enables to divide the territory
OF LEVEL 1 OF of Apollonia in two main zones: 1) the hilly area, less susceptible
APOLLONIA
to seismic amplification; 2) the coastal plain, more susceptible to
seismic amplification, given the presence of Quaternary very soft
sediments.
Where the weaknesses are?
The main uncertainties are related 1) to not well known
distribution of lithotypes characterizing the geological bedrock,
and 2) to not well known thickness of the Quaternary cover in the
lateral valleys and coastal plain. For this motive is desirable that
these uncertainties can be reduced through i) a detailed
geological-geotechnical survey of the archaeological area, and ii)
the use of geophysical methods which provide information on the
thicknesses of the recent soft covers.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

16. GEOLOGICAL
SURVEY FOR
LEVEL 1 SEISMIC
MICROZONATION
Different
lithotypes
behave in
different ways
when interested
by a seismic
wave: they have
to be carefully
mapped.
Zones Berat
susceptible of
permanent
deformations in
seismic
conditions (i.e.,
landslide prone
areas) have also
to be mapped.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

17. NEW
GEOPHYSICAL
SURVEY FOR
LEVEL 1 SEISMIC
MICROZONATION
Microtremor
measurements
performed to
define site the
fundamental f0=Vs/4H Berat
frequencies, THE CASTLE
i.e., soil
resonance
frequencies
when affected
by an
earthquake
event.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

18. NEW
GEOPHYSICAL
SURVEY FOR
LEVEL 1 SEISMIC
MICROZONATION
Microtremor
measurements
performed to
define site the
f0=Vs/4H Berat
fundamental
frequencies, THE OSUM RIVER
i.e., soil
resonance
frequencies
when affected
by an
earthquake
event.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

19. 1200 m/s
NEW
GEOPHYSICAL
SURVEY FOR
LEVEL 1 SEISMIC
MICROZONATION Berat
MASW enable
THE CASTLE
to characterize
the velocity
structure of the
subsoil. The
lower the shear
velocity Vs, the
poorer the
«quality» of the
soil in terms of
site response.
The higher the
velocity
contrast
between
superimposed
layers of soils,
the higher the
susceptibility to
local seismic
amplification.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

20. NEW
GEOPHYSICAL
SURVEY FOR
LEVEL 1 SEISMIC < 200 m/s
MICROZONATION
MASW enable
to characterize
the velocity
structure of the
subsoil. The
lower the shear
velocity Vs, the
poorer the
«quality» of the
soil in terms of
site response.
The higher the
velocity
contrast
between
superimposed
layers of soils,
the higher the 1300 m/s
susceptibility to Berat
local seismic THE OSUM RIVER
amplification.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

21. SUSCEPTIBILITY
TO INSTABILITY
Define zones
susceptible to
geological
instability, i.e.,
slope instability,
differential
settlement,
liquefaction, in
Berat
which the THE HISTORIC CENTER
predominant and
expected seismic
effects are due to
permanent
deformations
(amplification of
ground motion is
also possible).
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

22. SEISMIC
MICROZONATION
OF LEVEL 1 OF
BERAT
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

23. What is critical?
SEISMIC
MICROZONATION No relevant Vs contrasts were recorded in Berat, except for the
OF LEVEL 1 OF Osum River valley, even if steep slopes can induce local seismic
BERAT
amplification and trigger gravitational instabilities.
By the way, the main geohazard affecting the city of Berat is
represented by the instability of rock escarpments overlooking
the historic city center. The risk related to this criticality is high in
static conditions and could be even higher if a seismic event
should occur.
Where the weaknesses are?
We suggest to carry out a detailed study of structural and
geomechanical setting of the limestone cropping out along the
escarpments, if not already available.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

24. GEOLOGICAL
SURVEY FOR
LEVEL 1 SEISMIC
MICROZONATION
Different
lithotypes
behave in
different ways
when interested
by a seismic
wave: they have
to be carefully
mapped.
Zones Butrint
susceptible of
permanent
deformations in
seismic
conditions (i.e.,
landslide prone
areas) have also
to be mapped. fault scarp
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

25. NEW
GEOPHYSICAL
SURVEY FOR f0=Vs/4H
LEVEL 1 SEISMIC
MICROZONATION
Microtremor
measurements
performed to
define site the
fundamental
frequencies,
i.e., soil
resonance
frequencies
when affected
by an
earthquake
event.
Butrint
TRICONCH PALACE
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

26. NEW
GEOPHYSICAL
SURVEY FOR
LEVEL 1 SEISMIC
MICROZONATION
Microtremor
measurements
performed to
define site the
fundamental
frequencies,
i.e., soil
resonance
frequencies
when affected
by an
earthquake
event.
topographic effect
Butrint
ACROPOLIS
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

27. SUSCEPTIBILITY
TO INSTABILITY
coastal plain
rock falls
differential settlements
Butrint
THEATRE AND DWELLING WITH ATRIUM
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

28. SEISMIC
MICROZONATION
OF LEVEL 1 OF
BUTRINT
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

29. What is critical?
SEISMIC
MICROZONATION
The territory of Butrint is heterogeneous in terms of susceptibility
OF LEVEL 1 OF to seismic amplification, due to extreme geological variability.
BUTRINT The most critical zone in terms of possible site amplifications is
the coastal plain. High susceptibility to geological instability, both
for differential settlements and rock falls, is related to the
presence of the fault scarp bounding the Acropolis.
Where the weaknesses are?
The seismic microzonation of level 1 of Butrint is affected by high
level of uncertainty because of the lack of information about
lithology, thickness, and shear wave velocity of the lithotypes.
Lithostratigraphic and geometric uncertainty could be pulled
down by means of one deep borehole located close to the Vivari
channel, associated with Electrical Resistivity Tomographies
(ERTs) oriented perpendicular to the fault scarp. Shear wave
velocity could be detected by means of MASW measurements.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

30. GEOLOGICAL
SURVEY FOR
LEVEL 1 SEISMIC
MICROZONATION
Different
lithotypes
behave in
different ways
when interested
by a seismic
wave: they have
to be carefully Gjirokastra
mapped.
Zones
susceptible of
permanent
deformations in
seismic
conditions (i.e.,
landslide prone
areas) have also
to be mapped.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

31. NEW
GEOPHYSICAL
SURVEY FOR f0=Vs/4H
LEVEL 1 SEISMIC
MICROZONATION
Microtremor
measurements
performed to
define site the
fundamental topographic effect Gjirokastra
frequencies. THE CASTLE
These
frequencies are
related to the
thickness of
soft soils
covering the
basal rigid
bedrock
through the
shear velocity,
Vs.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

32. NEW
GEOPHYSICAL
SURVEY FOR
LEVEL 1 SEISMIC
MICROZONATION
Microtremor
measurements
performed to
define site the
fundamental Gjirokastra
frequencies.
These THE STADIUM
frequencies are
related to the
thickness of
soft soils
covering the
basal rigid
bedrock
through the
shear velocity,
Vs.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

33. SUSCEPTIBILITY
TO INSTABILITY
debries flows from
alluvial fan
historic walls
fractured
conglomerates
castle
rafting blocks
Gjirokastra rafting blocks
TOPPLED BLOCKS
AND ALLUVIAL FAN
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

34. SEISMIC
MICROZONATION
OF LEVEL 1 OF
GJIROKASTRA
Z1 Z2 Z3 Z4 Z5-Z6
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

35. What is critical?
SEISMIC
MICROZONATION
The most critical zones in terms of possible site amplifications:
OF LEVEL 1 OF 1) buried narrow valleys located at the mouth of mountain
GJIROKASTRA streams (zone 4), carrying high volumes of coarse clastic
materials to the valley Drino River; 2) narrow ridges bonding the
buried valleys, where topographic effects highlighted by
microtremors measurements could induce site amplification.
A rigid fractured layer of conglomerates generally occupies the
top of the narrow ridges (e.g., where the castle is located) and is
highly susceptible to rock falls and toppling of isolated blocks.
Where the weaknesses are?
Neither direct observation of subsoil nor Vs information are
generally available for the site. No geotechnical parameters are
available for a proper evaluation of the dynamic behavior of soils
and rocks. An additional investigation survey and the passage to
a level 3 of seismic microzonation is suggested.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

36. What is useful for?
SEISMIC
The seismic microzonation of level 3 is an advanced map that allows
MICROZONATION
quantitatively to define homogeneous zones - in terms of site response -
OF LEVEL 3
for a specific seismic input, i.e., for a specific earthquake scenario.
How is created?
The input information can be summarized as follow:
1) topographic (e.g., maps and Digital Terrain Models) and
geomorphological (e.g., escarpments and landslides) information;
2) geological maps with information on lithotype, i.e., “different kinds of
rocks or terrains”;
3) already available and new geological, geotechnical, and geophysical
information from boreholes and other in situ and laboratory tests;
4) evaluation of the seismic bedrock depth from noise measurements.
5) seismic input from one or more earthquake scenarios.
Numerical modeling allows quantitatively to define site effects.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

37. Seismic microzonation of level 3 - Dynamic parameters
Vertical velocity gradient of the anthropic layer
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

38. Seismic microzonation of level 3 - Seismic input
Characteristics of the seismicity affecting Berat (left) and
reference spectra selected for the microzonation (right)
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

39. Seismic microzonation of level 3 - Modeling of local
seismic response Cross-section 7
Cross-section 2
Coliseum
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

40. 0.8
trale, Sa(g)spettrale, AccelerazioneAccelerazione spettrale, AccelerazioneAccelerazione spettrale, AccelerazioneAccelerazione spettrale, Sa(g)
2A
input
0.6
0.8
0.4
spettrale, Sa(g)
3E
input
0.6
0.2 Seismic microzonation maps of level 3 and response spectra
0.4
0
0 0.5 1 1.5 2 lower or
Periodo, T(s) no mplification
0.2
0.8
Sa(g)
2B
0 input
0.6 0 0.5 1 1.5 2
Periodo, T(s) higher
0.8
0.4
SAN TEODORO’S amplification
spettrale, Sa(g)
CHURCH 3F
input
0.6
0.2
0.4
0
0 0.5 1 1.5 2
0.2 Periodo, T(s)
0.8
Sa(g)
2C
0 input
0.6 0 0.5 1 1.5 2
Periodo, T(s)
0.8
0.4
spettrale, Sa(g)
3G
input ARCH OF TITUS
0.6
0.2
0.4
0
ARCH OF TITUS SAN TEODORO’S
0 0.5 1 1.5 2 CHURCH
Periodo, T(s)
0.2
0.8
Sa(g)
2D
0 input
0.6 0 0.5 1 1.5 2
Periodo, T(s)
0.8
0.4
lerazione
3H
input
0.6
0.2
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

41. Concluding remarks and future works
• Cooperation among the involved Institutions has been crucial for the project.
• The application presented in this work clearly demonstrates the potential for
full integration of geological, geophysical, and archaeological methodologies.
• Seismic microzonation in historical centers and archaeological areas is
strongly conditioned by the availability of data. For the sites of this project,
scarcity of data is the main factor affecting the reliability of seismic
microzonations of level 1.
• An integration of existing surveying is recommended for all the investigated
Albanian Cultural Heritage sites. Seismic microzonation of level 3 is
recommended for evaluating local seismic amplification, aimed at seismic risk
prevention and mitigation.
• Regarding seismic microzonation, addenda to available guidelines (i.e., for
seismic microzonation) is specifically required for archaeological areas or for
historical center of ancient and permanent urbanization.
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012

42. Coming soon
Special issue of the Bulletin of Earthquake Engineering on:
Seismic Microzonation of the Central Archaeological
Area of Rome
Editors: Massimiliano Moscatelli, Alessandro Pagliaroli, Gian Paolo Cavinato
(National Research Council), Sergio Castenetto, Giuseppe Naso (Italian Civil
Protection Department)
Contribution focused on:
Cultural heritage - proposal of guidelines for
evaluating local seismic hazard
Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012