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Disaster Risk Preparedness & Management: Cavinato - II

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  • 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, AlbaniaConference 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 sitesConference 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. ApolloniaConference 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 INSTABILITYDefine zones crownssusceptible togeologicalinstability, i.e.,slope instability,differentialsettlement,liquefaction, in Apolloniawhich thepredominant and THE THEATREexpected seismiceffects are due topermanentdeformations(amplification ofground motion is earth flowalso possible). accumulationConference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012
  • 14. SEISMIC MICROZONATION OF LEVEL 1 OF APOLLONIAConference 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 INSTABILITYDefine zonessusceptible togeologicalinstability, i.e.,slope instability,differentialsettlement,liquefaction, in Beratwhich the THE HISTORIC CENTERpredominant andexpected seismiceffects are due topermanentdeformations(amplification ofground motion isalso possible).Conference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012
  • 22. SEISMIC MICROZONATION OF LEVEL 1 OF BERATConference 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 scarpConference 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 PALACEConference 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 ACROPOLISConference 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 ATRIUMConference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012
  • 28. SEISMIC MICROZONATION OF LEVEL 1 OF BUTRINTConference 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 FANConference 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-Z6Conference 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 layerConference 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 ColiseumConference 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 0.2Conference 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 hazardConference on Disaster Risk Preparedness and Management in Cultural Heritage Sites. Berat, 8th May 2012