Jesús Henares2 and Mohamed Hamdache4 EIGHTH INTERNATIONAL CONFERENCE ASSIUT 2015 ON THE GEOLOGY OF AFRICA A NEW PROPOSED SEISMIC SOURCE MODEL FOR THE SEISMIC HAZARD ASSESSMENT OF EGYPT Rashad Sawires1,*, Hamza A. Ibrahim1, José A. Peláez2, Raafat E. Fat-Helbary3, Jesús Henares2 and Mohamed Hamdache4 1 Geology Department, Assiut University, 71516 - Assiut, Egypt. 2 Department of Physics, University of Jaén, Jaén, Spain. 3 Aswan Regional Earthquake Research Centre, 152 - Aswan, Egypt. 4 Départment d’Etudes et Surveillance Sismique, CRAAG, Algiers, Algeria. * rashad.sawires@aun.edu.eg

Schematic description of the classical PSHA methodology. INTRODUCTION SEISMIC HAZARD is defined as the probability of occurrence of an earthquake or earthquake effects of certain severity, within a specific period of time, in a given area. A seismic source model that defines the spatial distribution of earthquakes within the region of concern. An earthquake recurrence model that describes the recurrence of events in time within the seismic source zones. A ground-motion attenuation model that describes mathematically the manner in which earthquake ground-motions decrease with distance from an earthquake source for various magnitude levels. A probability model for calculating the expected maximum amplitude of ground-motion within a given period of time corresponding to a chosen probability level. Schematic description of the classical PSHA methodology.

Motivation of the Study Global tectonic sketch for Egypt and its vicinity (modified from Ziegler, 2001 and Pollastro, 2003)

Motivation of the Study A damaging earthquake is a real, as well as a current, threat to the safety, social integrity, and economic wellbeing of the population in the region. The definition of the potential seismic sources, in a particular region, is a very important input for seismic hazard assessment studies. high seismic risk 2. Most of the densely-populated cities are located near moderate to high active seismic foci. 1. The population, as well as all important and archaeological sites, are concentrated within a narrow belt. moderate seismic activity 4. The soil characteristics in different localities have a clear impact on seismic wave attenuation and amplification. 3. The methods of construction vary between old (e.g., villages) and new buildings with poor construction practice. MW 7.2, November 22, 1995 Gulf of Aqaba earthquake MS 5.9, October 12, 1992 Dahshour (Cairo) earthquake 545 killed, 6512 injured, 50000 homeless, 350 collapsed buildings, and 9000 damaged buildings.

OBJECTIVES DATA SOURCES Delimitation and characterization of a new seismic source model, for seismic active regions in and around Egypt, based on the known geological, seismological and geophysical information. Defining the earthquake recurrence characteristics of each defined seismic zone separately. DATA SOURCES Crustal Structure Data An Earthquake Catalogue (2200 B.C. – 2013) Focal Mechanism Solutions Data (1940 – 2013) Active Faults Data

Depth of Moho discontinuity in Egypt (after Abdelwahed et al., 2013). DATA SOURCES 1. Crustal Structure Data It was used for the discrimination between the crustal (shallow-depth) seismicity, the intermediate-depth, and the deeper one. This Moho Discontinuity is located at depth of: 31-33 km ….around Greater Cairo, 32-35 km ….in Sinai Peninsula, 33–35 km ….along the Nile River, 30 km …. near the Red Sea coast, and 39 km ….towards the Western Desert. We used a mean value of 35 km, for the Moho discontinuity, to discriminate between the shallow- and intermediate-depth earthquake events. Depth of Moho discontinuity in Egypt (after Abdelwahed et al., 2013).

Declustered shallow seismicity (h ≤ 35 km). DATA SOURCES 2. An Earthquake Catalogue (2200 B.C. – 2013) A complete and consistent earthquake catalogue in a region is the keystone for any seismotectonic and seismic hazard studies. http://www.ujaen.es/investiga/828 rnm024/Egypt-catalog.pdf Declustered shallow seismicity (h ≤ 35 km). Declustered seismicity (h ≥ 35 km).

DATA SOURCES 3. Focal Mechanism Solutions Data (1940 – 2013) Earthquake source mechanisms or FMS reflect the stress pattern acting in the area under study and may help to map its tectonic structure, which causes the earthquakes. Distribution of FMSs in and around Egypt. Blue (Strike-slip), green (Normal), red (reverse) Distribution of FMSs in Sinai Peninsula. Blue (Strike-slip), green (Normal), red (reverse)

DATA SOURCES 3. Focal Mechanism Solutions Data (1940 – 2013) Earthquake source mechanisms or FMS reflect the stress pattern acting in the area under study and may help to map its tectonic structure, which causes the earthquakes. Greater Cairo Nasser’s Lake Eastern Mediterranean (Shallow events) Eastern Mediterranean (Deep events)

DATA SOURCES 4. Active Faults Data Active-faults data, from the seismological point of view, is very scarce in Egypt. Only five active faults defined by WCC (1985) in the Nasser’s Lake region, in Southern Egypt, are considered to be active. NW-SE (Red Sea-Gulf of Suez) NNE-SSW (Gulf of Aqaba) E-W (Tethyan/Mediterranean) N-S (Nubian/East African) WNW-ESE (Drag) ENE-WSW (Syrian Arcs) NE-SW (Aualitic/Tibesti) Distribution of major surface and subsurface faults. Geological and tectonic features- Nasser’s Lake.

THE PROPOSED SEISMIC SOURCE MODEL Seismic Hazard Harmonization for Europe (SHARE, 2013) 2009-2013 (SHARE Project). 80 experts from 28 countries. 53 shallow (h ≤ 20 km) seismic sources. The Greek and Cyprian area (Papiouannou and Papazachos, 2000; Papiouannou, 2001). The Turkish model (Demircioglu et al., 2007; Demircioglu, 2010). Proposed shallow seismic source zones in Egypt and its surroundings.

THE PROPOSED SEISMIC SOURCE MODEL EG-11 (Lebanon) Imax IX-X, June 6, 1159 EG-10 (NW Saudi Arabia) Imax VIII, Jan. 4, 1588 EG-09 (Kineret-Hula Basin) Imax X, 19 A.D. EG-08 (Jordan Valley) Imax IX, 746 A.D. EG-07 (Dead Sea Basin) Imax VIII, Nov. 12, 1458 EG-06 (Eastern Central Sinai) mb 4.8, Sept. 24, 1927 EG-05 (Arava Valley) mb 5.2, Dec. 18, 1956 EG-04 (Eastern GOA) mb 4.5, Dec. 26, 1995 EG-03 (Elat Basin) Imax VIII-IX, May 2, 1212 EG-02 (Aragonese Basin) MW 7.2, Nov. 22, 1995 EG-01 (Tiran-Dakar Basin) mb 4.4, Feb. 2, 2006 Shallow seismicity and delineated seismic sources.

Shallow seismicity and delineated seismic sources. THE PROPOSED SEISMIC SOURCE MODEL EG-17 (Northern GOS) MS 6.6, 1754 A.D. EG-16 (Central GOS) MS 6.2, Mar. 6, 1900 EG-15 (Southern GOS) MW 6.8, Mar. 31, 1969 EG-14 (Northern RS) mb 5.0, Mar. 22, 1952 EG-13 (Central RS) mb 4.7, July 30, 2006 EG-12 (Southern RS) Imax VI-VII, 1121 A.D. Shallow seismicity and delineated seismic sources.

THE PROPOSED SEISMIC SOURCE MODEL EG-28 (El-Gilf El-Kebeir) MS 5.3, Dec. 9, 1978 EG-27 (Western Med. Coast) Imax VIII, 262 A.D. EG-26 (Northern Delta) mb 6.5, Sept. 12, 1955 EG-25 (Eastern Med. Coast) Imax X, Jan. 14, 1546 EG-24 (Beni Suef-Cairo-Suez District) Imax IX-X, 1262 A.D. EG-23 (Luxor-Southern Beni Suef) Imax VIII, 857 A.D. EG-22 (Southern Aswan) MW 5.8, Nov. 14, 1981 EG-21 (Abu Dabbab) mb 6.2, Nov. 12, 1955 EG-20 (Southern Abu Dabbab) ML 4.7, Jan. 21, 1982 EG-19 (Southern ED) ML 3.9, July 15, 1991 EG-18 (Western RS Coast) ML 4.5, May 23, 1990 Shallow seismicity and delineated seismic sources.

THE PROPOSED SEISMIC SOURCE MODEL Tectonic map, Intermediate-depth seismicity and delineated seismogenic source zones.

SEISMICITY PARAMETERS b-values, annual rates of earthquakes, approximate completeness periods, and maximum observed and expected magnitudes for the delineated seismic sources. Gutenberg-Richter (1944) (*) The most recent event, (**) Macroseismic surface-wave magnitude (after Ambraseys et al., 1994). A Calculated using Robson-Whitlock-Cooke procedure. B Equal to maximum recorded magnitude. C Taken from Deif et al. (2009, 2011).

Summary and Conclusions The current work is an attempt to develop and propose a new seismic source model for Egypt and its surroundings, using available geological, geophysical, tectonic and earthquake data, aimed at carrying out seismic hazard and forecasting studies. Focal mechanism solutions data, active faults data, as well as an updated earthquake catalogue for the period 2200 B.C.–2013 were taken into account. Potential seismic sources are modelled as area sources, in which the configuration of each seismic source is controlled, mainly, by the fault extension and seismicity distribution. The proposed seismic source model consists of 28 shallow seismic zones (h ≤ 35 km) for the Egyptian territory and its surroundings. In addition, 53 shallow seismic sources (h ≤ 20 km) for the Eastern Mediterranean region have been considered after SHARE (2013). Furthermore, the current model involves 7 delineated intermediate-depth seismic sources (20 ≤ h ≤ 100 km) covering the intermediate-depth seismicity in the Eastern Mediterranean region.

Summary and Conclusions Seismicity parameters (b-values and activity rates) of the Gutenberg–Richter magnitude–frequency relationship have been estimated for each one of the seismic sources. In addition, the maximum expected magnitude for each seismic source zones was reported.

A NEW PROPOSED SEISMIC SOURCE MODEL FOR THE SEISMIC HAZARD ASSESSMENT OF EGYPT