ANNUAL REPORT 1998

Summary

Goal of the IGCP n.382 project Seismotectonics and Seismic Hazard Assessment of the Mediterranean Basin (SESAME, 1996-2000) is to produce a uniform seismotectonic zonation and seismic hazard assessment for the Mediterranean region. The project aims to increase the use of geological evidence in seismic hazard assessment by adopting a uniform probabilistic seismotectonic approach to compute seismic hazard throughout the Mediterranean and by incorporating geological evidence to supplement the historical record of seismicity in building a statistical model of seismogenic sources. The SESAME strategy is based on the integration and coordination of national, multi-national and regional programs operating in the Mediterranean.

Programs and test-areas for multi-national seismic hazard assessment have been active in different areas of the Mediterranean area: Ibero-Maghreb, central-northern Europe, Pannonian Basin, Adriatic Sea, Middle-East, Caucasus, Greece and Turkey. In coordination with the Global Seismic Hazard Assessment Program (ILP, ICSU, UN/IDNDR) and with the European Seismological Commission, SESAME has set up a schedule for the standardization of data bases, assessment methodology and hazard maps, and for the integration of the regional results into a homogeneous source zones and hazard mapping for the whole Mediterranean basin. The GSHAP (1992-1998) is now finished and the publication of the volume of regional reports and of the global map is expected for February 1999, while SESAME and the Working Group on Seismic Hazard of the European Seismological Commission (ESC/WG-SHA) will continue until the year 2000 for the Mediterranean area. The work is conducted in three phases:

1. 1996-97: the aim and activities of SESAME, the ESC/WG-SHA and GSHAP coincided; regional mapping of source zones and hazard were conducted in the different test-areas; in 1997 the regional results were presented at the 29th IASPEI Assembly (Thessalonicki, 8/97); in some regions (see below), work is ongoing.
2. 1997-98: the intermediate goal of merging the regional hazard results into a preliminary regional PGA map was reached at the 26th ESC Assembly (Tel Aviv, 8/98), making possible to identify regions requiring further work and to set up a common stategy for Phase III.
3. 1998-2000: the aim is to construct a homogeneous model of source zones for the whole Mediterranean to compute for the first time a suite of regional hazard maps in spectral parameters.

The present report summarizes the progress and cooperation in regional seismic hazard assessment, the achievements and specific activities/meetings of SESAME in 1997-98, the plans for 1998-2000, the 1998 budget and the main publications.

Progress in regional SHA in the Mediterranean

SHA in the Mediterranean area is coordinated under a number of regional, multi-national and national initiatives. Here we first describe the progress in the different areas, then summarize the work done toward achieving a basic level of unification in the whole Mediterranean. All details on activities in previous years are found in the SESAME report 1996-97.

CENTRAL-NORTHERN EUROPE

Minor changes have been made with respect to the GSHAP implementation in Central-Northern Europe, coordinated by the GFZ Regional Centre in Potsdam and including the territory north of 46°N. The seismic hazard for France has now been completed also south of 46°N and a second hazard zonation is now available for Poland, Czech Republic and Slovakia, coordinated by Prague University.

IBERO-MAGHREB

This project, coordinated by CSIC in Barcelona, includes Spain, Portugal, Morocco, Algeria and Tunisia. The catalogue, homogeneous zoning and SHA map were completed in 1997, as detailed in the SESAME 1996-97 report.

ADRIA

This project includes all countries bordering on the Adriatic Sea (Italy, Switzerland, Austria, Slovenia, Croazia, Albania, Greece) coordinated by OGS of Trieste. A final iteration on the source zone model and the seismic hazard was conducted in Pisa (2/98; sponsored by SESAME), and the final model hazard results presented at the 1998 ESC assembly (Tel Aviv, 8/98).

EASTERN MEDITERRANEAN

The IGCP-SESAME and the UNESCO/USGS RELEMR are coordinating their activities toward a unified hazard mapping for the whole area (Turkey, Syria, Lebanon, Cyprus, Israel, Jordan, Egypt, Palestine, Saudi Arabia and Arabian Peninsula). Several planning and review meetings have been held so far in the area. In 1996 and 1997 SESAME organized two Training workshops on seismotectonics and seismic hazard analysis in the Eastern Mediterranean countries (Cairo, 12/96, 12/97). RELEMR organized workshops and special sessions dedicated also to hazard assessment in Cyprus (12/96), Thessalonicki (8/97) and Cyprus (10/97). Following this last meeting, joint SESAME/RELEMR activities were conducted in 1998 with the aim of producing a prelimanry regional map of SHA, starting from existing regional PGA maps, and to verify the feasibility of a common strategy for future regional zoning. During the winter 1998, all existing hazard maps for the area were transferred to ETH Zurich, digitized and joined into a common geographic gridding. This first product was then critically analyzed by all contributing countries in Amman (5/98; sponsored by SESAME), with the aim to homogeneize the maps and smooth border discontinuities. After a second mapping iteration, the final preliminary map for the Near East was presented and discussed in Tel Aviv (8/98; sponsored by SESAME). A third workshop was organized by RELEMR in Istanbul (10/98), where a new strategy to build a commont earthquake catalogue, source zones and common hazard has been established for the whole region.

CAUCAS

The project includes the Caucasian Republics (Armenia, Ukraine, Georgia, Turmenistan, Azerbaijan), Russia, Iran and Turkey. The coordinated catalogue, homogeneous zoning and SHA map were completed in 1997, as detailed in the SESAME 1996-97 report.

NORTHERN EURASIA

The JIPE of Moscow is coordinating the seismic hazard mapping for the whole FSU territory. This five-year program, initiated before the FSU break-up and interrupted during the period of more intense political turmoil, has been restarted, leading to the compilation of the seismic catalogue and the SHA, using for the first time a probabilistic approach. Technical workshops are held routinely in Moscow. The whole area has been subdivided in five blocks, and the final catalogue, the model of source zones and lineaments and the hazard maps were released in early 1998.

CIRCUM-PANNONIAN

The EU-QSEZ-CIPAR project includes the countries of the Circum-Pannonian basin: Hungary, Romania, Slovania, Croatia, Albania in addition to Italy and UK. While the aim of this independent project was to produce a deterministic hazard assessment for the region, a specific source zoning (1997) and probabilistic hazard assessment (1998) were produced by BGS, Edinbourgh, for comparison with the deterministic results and for inclusion in SESAME and GSHAP.

GREECE

The official national hazard map of Greece has been contributed to the SESAME Mediterranean map (see below), while a new schedule to produce a national source zone model (not yet existing) and a new hazard map adjusted in critical border areas has been now established for 1999 by the groups in Thessalonicki and Athens.

TURKEY

The Kandilli Observatory of Istanbul has represented Turkey in the activities of the Caucasus and Eastern Mediterranean projects. Following the evaluation of the preliminary Mediterranean map (see below), a revised zoning and hazard maps are being produced to correct discrepancies in the Aegean and Eastern Anatolia border areas.

SESAME hazard map

During 1997-98 the GFZ of Potsdam lead the efforts to collect and fit together the SHA maps derived in the individual regional projects described above. The preliminary PGA map includes the contributions of Ibero-Maghreb, Adria, Central-Northern Europe, Northern Eurasia, Caucasus, Greece, Turkey and Circum Pannonian and is accompanied by a compilation of the individual source zones (see figures). The draft maps were presented and amply discussed at the 1998 26th ESC assembly (Tel Aviv, 8/98) during the SESAME special events. The Near-East map was presented separately. The joint evaluation allowed to identify areas requiring further work, to smooth out border problems and set up a precise schedule of activities for the year 1998-2000 (see below). The draft regional map has been widely circulated and can be retrieved from the net (http://www.seismo.ethz.ch) to extend the evaluation to the larger ESC community.

SESAME events 1998

Several technical workshops were organized in the Western and Eastern Mediterranean, within the regional framework described above. Three were specifically supported by SESAME.

1. workshop in Pisa to finalize the ADRIA seismic source zones and SHA; Feb 5-6 ; SESAME funding 2,000$; participants from Italy, Greece, Croatia, Albania
2. workshop in Amman for the first iteration of the Middle-East PGA map; May 4-7; SESAME funding 2,500$; participants from Israel, Cyprus, Palestine, Jordan, Egypt, Lebanon, US
3. workshop in Tel Aviv for the second iteration of the Middle-East PGA map; August 27-28; SESAME funding 1,750$; participants from Israel, Cyprus, Palestine, Jordan, Lebanon, US

The SESAME key event of 1998 took place in occasion of the 26th ESC Assembly (TelAviv, August 27), where symposium SC-F2 was dedicated to the presentation of results in the different regions, to the presentation and discussion of the preliminary PGA map of the Mediterranean and to the definition of the goals and work schedule for 1998-2000.

SESAME planned activities 1998-2000

Following the strategy decided in TelAviv (8/97), SESAME and the ESC/WG-SHA have planned the following 5 steps program:

1. The draft PGA map obtained by the compilation and fit of different regional PGA maps is refined and smoothed to produce a reference PGA map for the Mediterranean to be included in the global GSHAP map; the work is lead by GFZ, interactive with the individual areas, and is scheduled to end in December 1998.
2. The EU-sponsored BEECD project has finalized in October 1998 the compilation of the first homogeneous European catalogue geared to hazard computation; this catalogue will be extended by the year 2000 to cover more areas of the Mediterranean, under the guidance of the IRRS of Milan. In parallel, the RELEMR group has started the merging of national databases in the Near East to compile a regional catalogue.
3. The first SESAME product has been a compilation of the source zones obtained in the different regions; by the year 2000 a homogeneous model of seismogenic sources for the Mediterranean will be delivered by SESAME. Starting from the existing zones, the effort will be to adopt more uniform criteria to deal with size and dimension of source zones, relation to active tectonic features, characterization of the seismic statistics in the zones, back-ground and diffuse seismicity, across-boundary continuity.
4. One of the remaining elements of discontinuity in the Mediterranean is the adoption of different attenuation laws and related uncertainties in different areas of the Mediterranean. SESAME plans to select a suite of attenuation laws for different tectonic domains in the region.
5. The final SESAME goal for 2000 will be a new generation of regional hazard for the Mediterranean computed in uniform fashion from the regional catalogue, source zones model and attenuation laws. When possible, a suite of maps will be produced covering a range of spectral responses.

Work is in progress in different European and Mediterranean centers toward these goals.

Publications

The regional reports are now submitted for publication in the GSHAP final volume, in press for early 1999 on Annali di Geofisica. The reports detail databases, procedures and results. In addition, a CD-ROM with the regional databases and a printed global map are under production, and will be included in the Annali di Geofisica volume.

The regional reports, the regional and global maps and the SESAME reports are being loaded on the web at http://www.seismo.ethz.ch.

Budget 1998

The SESAME budget for 1998 was of 6,250$. It was used as seed money to support the workshops in Pisa (2,000$), Amman (2,500$) and TelAviv (1,750$). Separate contracts have been signed by the meeting organizers with the UNESCO Cairo Office, which handled directly all administration.

The plan for 1999 (see above) is to use the IGCP contribution to continue supporting the activities in the Middle East, with a workshop in preparation devoted to seismic catalogue and especially to source zones, and to support a regional workshop to be attented by representatives of the different regions, which will come together to evaluate the first regional source model and the results of comparative tests of different attenuation laws as a first step toward regional hazard assessmen. Dates and venues for these workshops are under discussion.

Report prepared on November 15, 1998, by Domenico Giardini