Earthquake vulnerability and risk modeling for the area of Greater Cairo, EgyptEarthquake vulnerability and risk modeling for the area of Greater Cairo, EgyptEarthquake vulnerability and risk modeling for the area of Greater Cairo, EgyptTanja Liesch (1), Sergey Tyagunov (3), Kamal Abdel-Rahman (2), Sherif El-Hady (2), Abuo El
(1) cedim AG, Karlsruhe, Germany; (2) National Research Institute of Astronomy and Geophysics (NRIAG),
(3) Center for Disaster Management and Risk Reduction Technology (CEDIM), University of Karlsruhe, Germany;
(4) GeoForschungsZentrum(4) GeoForschungsZentrum
A. Description of the Area
A.1 IntroductionA.1 Introduction
Though the earthquake hazard in Cairo is lower than in the other test cities considered in the EU-SAFER project,the city has been chosen for a pilot study. The reasons were mainly that for the other cities, a lot of studiesconcerning earthquake vulnerability and risk have already been carried out, whereas for Cairo there is backlog inconcerning earthquake vulnerability and risk have already been carried out, whereas for Cairo there is backlog inthis case. On the other hand, Cairo poses a real challenge, especially concerning vulnerability, since the city'sbuilding stock is very heterogeneous, vulnerable, and additionally changing quite fast.
During a visit to Cairo in March 2008 CEDIM and cedim AG have collected missing data concerning theadministrative grid of settlements and distributions of buildings. Data of population and administrative grid wereprovided by NRIAG, the information about the residential building stock were collected by CEDIM and cedim AG.These data have been integrated in the Seismic Risk Explorer, with which seismic scenarios for Cairo can becarried out.
Fig. 1: Seismic Hazard Map,
Tunisia/Libya/Egypt (Global
Seismic Hazard Assessment
Programme,1999)
A.2 Seismic Hazard and Destructive Earthquakes
The Seismic Hazard Map of Egypt shows a peak ground acceleration (PGA), which can be expected for a sitewith 10 percent probability during the next 50 years up to 1.6 m/s² (fig. 1). This might be comparably low, and sowith 10 percent probability during the next 50 years up to 1.6 m/s² (fig. 1). This might be comparably low, and somost of the reported earthquakes from the Nile valley have magnitudes of less than 5. However, as more than 12million people are living in the Cairo area, many of them in poorly constructed buildings, and as strong sitedependent ground motion amplifications may occur especially in the Nile Delta, the vulnerability in this region isdependent ground motion amplifications may occur especially in the Nile Delta, the vulnerability in this region isextremely high (SAFER, 2006). Additionally, the deep alluvial Nile Valley is susceptible to shaking andliquefaction.
The last two recent destructive earthquakes in Egypt occurred on 12th October 1992 (M = 5.3) and 22ndThe last two recent destructive earthquakes in Egypt occurred on 12th October 1992 (Mw = 5.3) and 22nd
November 1995 (Mw = 7.2). These earthquakes caused large damage in a wide area of Egypt. Considerabledamage from the October 1992 earthquake, in particular, occurred in the south western districts of Cairo as e.g.El-Tibeen (fig. 2). 370 fatalities and over 3000 injured were reported. In spite of the higher magnitude, theEl-Tibeen (fig. 2). 370 fatalities and over 3000 injured were reported. In spite of the higher magnitude, theNovember 1995 earthquake, which was located in Gulf of Aqaba and especially hit Nuweiba City, caused a lowerdamage. Only 11 people were killed and 47 injured. These different damage locations indicate the considerableimpact of the local geology, which must be taken into consideration for engineering design and construction. Fig. 2: Damage from the 1992 earthquake in the district of El Tibeenimpact of the local geology, which must be taken into consideration for engineering design and construction. Fig. 2: Damage from the 1992 earthquake in the district of El Tibeen
B.2 Computing Algorithm B.3 Computing of ScenariosB.2 Computing Algorithm
On the base of the collected information, combining the findings of the fieldinvestigations in different districts with available statistical data about the
B.3 Computing of Scenarios
We generate a “fishnet” of rectangular cells (grey rectangular polygons), whichare used for calculating intensity distribution from scenario earthquakes. The sizeinvestigations in different districts with available statistical data about the
distribution of buildings in the districts, we constructed vulnerabilitycomposition models (in terms of the vulnerability classes of the EuropeanMacroseismic Scale, EMS-98, fig. 5-7) as well as vulnerability curves (in
are used for calculating intensity distribution from scenario earthquakes. The sizeof the cells can be assigned depending on the scale and the purposes of thestudy. For the area of Greater Cairo we use the cells of 1 km x 1 km. The intensityvalues are calculated for the centers of the cells with the attenuation functionMacroseismic Scale, EMS-98, fig. 5-7) as well as vulnerability curves (in
terms of mean damage ratio versus seismic intensity) for all the considered43 districts of Greater Cairo (show in red in fig. 8)
The constructed vulnerability models have been included into the
values are calculated for the centers of the cells with the attenuation functionshown in B.4.
To refine the location of built-up areas we use satellite images, showing spatialdistribution of the building stock in the area (yellow polygons).The constructed vulnerability models have been included into the
Vulnerability Module of the developed tool (DDSM) and can be used foranalysis of probable damage and losses in case of occurring damagingearthquakes in the region.
distribution of the building stock in the area (yellow polygons).Further, combining the GIS-layers of the seismic input and the building stock withthe corresponding vulnerability models we calculate the damage and losses.
earthquakes in the region.
Fig. 6: Vulnerability curves for the classes A to D
Fig. 8: Steps of Computing Scenarios
A
C
DB.4 Attenuation Function
For the DDSM the following magnitude calibrated intensity attenuation relation
Fig. 8: Steps of Computing Scenarios
( ) ( )hR 22+
B
Fig. 5: EMS-98 differentiation of structures (buildings)
For the DDSM the following magnitude calibrated intensity attenuation relation provided by partner GFZ for Cairo has been implemented (SOERENSEN, personal communication, 2008)
( ) ( )hhR0.0035h
hRlog1.905.33hlog3.01M0.86I 22
2
22
W −+⋅−+
⋅−+⋅−⋅=Fig. 5: EMS-98 differentiation of structures (buildings)
into vulnerability classes (Vulnerability Table).
Fig. 7: Vulnerability composition for an example district of Cairo
cedim AGCEDIM - Center for Disaster Management
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Earthquake vulnerability and risk modeling for the area of Greater Cairo, EgyptEarthquake vulnerability and risk modeling for the area of Greater Cairo, EgyptEarthquake vulnerability and risk modeling for the area of Greater Cairo, EgyptEl-Ela Mohamed (2), Mathilde B. Soerensen (4), Lothar Stempniewski (3), Jochen Zschau (4)
AG, Karlsruhe, Germany; (2) National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Cairo, Egypt;
for Disaster Management and Risk Reduction Technology (CEDIM), University of Karlsruhe, Germany;
GeoForschungsZentrum Potsdam, Germany GeoForschungsZentrum Potsdam, Germany
B. Description of the Method
B.1 Earthquake Vulnerability and B.1 Earthquake Vulnerability and
Building Stock
In the period of the working visit to CairoIn the period of the working visit to Cairoduring the first half of March 2008, informationabout the existing residential building stockwas collected. Field investigations werewas collected. Field investigations wereconducted in 43 administrative districts ofGreater Cairo (including the City of Cairo, El-Giza and Shubra El-Kheima, see fig. 3) aimingGiza and Shubra El-Kheima, see fig. 3) aimingat identifying representative building types inthe area and assessing their seismicvulnerability. The following sources ofvulnerability. The following sources ofinformation were used:
1. Database of collected photos of the buildingstock (fig. 4), showing existing buildingstock (fig. 4), showing existing buildingtypes and their distribution in differentdistricts.
2. Database of building types (informationobtained from CAPMAS – Central Agencyfor Public Mobilization and Statistics offor Public Mobilization and Statistics ofEgypt), showing composition of the buildingstock (in terms of building material, year ofconstruction, number of floors, propertyconstruction, number of floors, propertysector, etc) in different districts.
3. Google Earth satellite images, showingspatial distribution of the building stock in Fig. 4: Some typical building structures in the area of Greater Cairo (first column, from spatial distribution of the building stock inthe area.
Fig. 4: Some typical building structures in the area of Greater Cairo (first column, from
top to down: Dar El Salam, Heliopolis, Maadi, El Marg, second column, from top to
down: El Giza, Bulaq, Imbaba, Helwan).Fig. 3: The 43 districts of Greater Cairo, including El-Giza and Shubra El-Kheima.
C. Results of the In Detail TestsC. Results of the In Detail Tests
Fig. 9 (left) shows the intensity map, computed with the above mentionedattenuation function, for the historical earthquake of October, 12th 1992, withattenuation function, for the historical earthquake of October, 12th 1992, withthe epicentre in the south-west of the city. The intensity was computed for theshown polygons, which represent the 43 districts. Some of them have beenbroken down into populated and unpopulated regions. Based on the intensitybroken down into populated and unpopulated regions. Based on the intensitymap, a damage map is computed, based on especially calibrated vulnerabilityfunctions, derived from the collected building stock data. Fig. 9 (right) showsthe damage map for the historical earthquake of October, 12th 1992. The mapthe damage map for the historical earthquake of October, 12th 1992. The mapshows a significant damage in the southern districts of Cairo, especially El-Hawamdia and El-Tibeen, which fits well to the observed damage in 1992,though the building stock has changed dramatically since then, which makes athough the building stock has changed dramatically since then, which makes acalibration very difficult.
Fig. 9: Calculated intensity map (left) and damage map (right) for the historical earthquake of 12-Oct-1992.
D. Earthquake Scenarios
As one of the hypothetical scenarios, the same coordinates as in 1992 werechosen, but with a higher magnitude of M =7.0, which some geologicalchosen, but with a higher magnitude of Mw=7.0, which some geologicalstudies believe to be possible, and a slightly lower depth of 18 km. Fig. 10(left) shows the according intensity map, which implies, that some districtsmight be affected with intensities up to 8. The corresponding damage map (fig.might be affected with intensities up to 8. The corresponding damage map (fig.10, right) indicates, that some of the south western districts might suffer amean damage ratio of more than 10 %.
The DDSM, that has been programmed, can be used as a risk managementThe DDSM, that has been programmed, can be used as a risk managementtool, that indicates, which districts might be most affected by a possible futureearthquake. Another possible application is estimation of damage for the rapidemergency response in the case of an actual earthquake. As soon as theemergency response in the case of an actual earthquake. As soon as thecoordinates, depth and magnitude of the earthquake are determined, thecomputation of the damage on residential buildings goes quick and is a goodtool for estimating possible fatalities and injuries.tool for estimating possible fatalities and injuries. Fig. 10: Calculated intensity map (left) and damage map (right) for a hypothetical earthquake of Mw=7, D=18 km.
Acknowledgement to NRIAG, Helwan, Cairo, Egypt; Dr. Sergey Tyagunov, CEDIM – Center for Disaster Management and Risk Reduction Technology, Karlsruhe, Germany.
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The shareholders of cedim AG:
Center for Disaster Management
Hans Fahr
Center for Disaster Management
Universität Karlsruhe (TH),Hertzstr. 16, Geb. 6.42
