EERI SPECIAL EARTHQUAKE REPORT -DECEMBER 1992

7

EERI SPECIAL EARTHQUAKE REPORT -DECEMBER 1992

cal parties were beginning to findsupport among the homeless,many of whom were still awaitingassistance from the governmentone week after the earthquake.

Mitigation and Preparedness

This earthquake emphasized theneed for developing mitigation andpreparedness measures in both pri-vate and public sectors throughoutthe country. Building codes werein the process of being modified atthe national level, however, localauthorities in rural areas expressedconcern about the practice of re-building in the same manner as be-fore the earthquake. In an effortto educate the local populationabout the hazards of natural disas-ters and appropriate building occu-pant behavior following earth-quakes, the Governor of Giza hadpamphlets of the U.S. DefenseCivil Preparedness Agency(predecessor agency to the FederalEmergency Management Agency)translated and distributed toresidents after the earthquake.

Recommendations

1 .An emergency response and dis-

aster preparedness program should

be implemented in both private and

public sectors at national, regional,

and local levels.

Building separation at expansion joints and tilting of some buildings.

2. Information regarding appropri-ate occupant actions within andoutside a structure should bedisseminated. Earthquake drillsshould be conducted in schools ona regular basis.

3. Disaster training should beconducted for all first responder

organizations.

~

4. Emergency plans, particularlyfor critical facilities such ashospitals, schools, and other firstresponder organizations, should bedeveloped, exercised, and revised

periodically.

Regular R. C. construction with in-filled wall performed well in villages.

NSF; Grant #CES 8822367 funded this investigation and the publication and

distribution of this report.

EERI SPECIAL EARTHQUAKE REPORT -DECEMBER 1992

'((

and the Red Crescent. The Armyoperated camps in the Cairo, Giza,and Oualubiya areas. Non-govern-mental organizations worked underthe direction of the Ministry ofSocial Affairs and the Red Cres-cent, and primarily addressed sani-tation issues. The Ministry ofHealth was responsible for provid-ing primary health care in thecamps and offered psychologicalconsultation when requested. Afood borne outbreak arose in onecamp where 28 residents purport-edly ate donated hot meals thatwere stored at room temperatureall day. According to the EgyptianRed Crescent, systems for thetimely and efficient identificationand distribution of appropriatedrugs, relief equipment, andsupplies were not in place.

from 3 grade schools in the Shou-bra district of Cairo were killed instampedes. Indirect deaths andinjuries are expected to increase asbuildings rendered unstable by theearthquake continue to collapse onthemselves or on adjacent struc-tures. Because building collapse isa common occurrence in Egypt andthe source of many injuries, it willbe difficult to determine whetherfuture structural collapses areattributable to the earthquake andits aftershocks or to inadequateconstruction that existed beforethe earthquake occurred.

The occurrence of the October 1 2,

1992, earthquake near Cairo pro-vided an opportunity to develop

important insights that can be usedto lessen human and structuralloss from earthquakes elsewhere inthe world. In addition to inves-

tigating geophysical and engineer-ing aspects of the earthquake, theEERI team evaluated emergencyresponse and social scienceimpacts-including mortality andmorbidity, search and rescue,displaced persons, economic andsocial impacts, and mitigation and

preparedness-and identified areasfor further in-depth study.

Search and Rescue

Search and rescue operations werenot a major requirement for thisearthquake, since only one multi-story structure collapsed. Foreignsearch and rescue teams, particu-larly from France, provided assis-tance. However, local area resi-dents rescued most of the victims,typically from 2-3 story structures,and brought them to medical facili-ties by ambulance or by taxi.

Emergency ResponseSocial and Economic Impacts

Although earthquakes occurred inthe Red Sea area in 1969 and in

~ Sharkiya Province in 1974, these(( )disasters were not recognized as

significant natural hazards inEgypt. No disaster preparednessor emergency response programsfor natural hazards existed atnational, regional, or local levelsprior to this earthquake. Criticalcare facilities were able to provideadequate emergency services inthe immediate response periodsince the structures and operationsof such facilities were not severelyaffected by the earthquake.

Displaced Persons

Human Casualties

Reports from the Ministry ofHealth indicated that a total of 490deaths had been registered official-ly as of October 26. Newspapersreported 557 deaths for the sameperiod. Of the 9,900 injuries thatwere treated and reported to date,a total of 2,276, or 23 percent,were admitted to hospitals of the

iU Ministry of Health. An estimated" 500 of these admissions occurred

during the first two days after theearthquake. A total of 41 children

The earthquake exacerbated analready severe housing deficitthroughout Cairo and urban Giza.In rural Giza, the earthquakeleveled entire villages such asEI-Beleida, EI-Atf, and Bedsa.Relocation to permanent housing innew areas and in satellite towns isbound to create long-term socialand economic effects. For some,the receipt of housing from thegovernment proved to be timelyand advantageous. As is common-ly seen following disasters, non-victims also attempted to secureaid from the government. .Becausefinancial compensation wasgranted to survivors of deceasedvictims, reports surfaced ofapplicants for assistance whopresented death certificates ofpersons who died prior to theearthquake or of fictitious deadrelatives. Moreover, some patientsreportedly prolonged their stay inhospitals past recovery in order toreceive assistance from foreigngovernments that distributedmonetary aid directly to the bed-side. As in Mexico City after the1985 earthquake, opposition politi-

According to initial reports by theDepartment of HumanitarianAffairs/United Nations DisasterRelief Office, an estimated 3,000families were homeless immediate-ly after the earthquake. Thisfigure is expected to rise as badlydamaged residential buildings aredemolished. By October 18,approximately 2,000 families inCairo were given new permanenthousing in satellite towns outsideCairo. An estimated 30 sheltershad been established in rural areasoutside of Cairo, 20 in urban Giza,and 20 in Cairo as of October 29.A number of families, particularlyin rural areas, refused to leavetheir plots of farmland and insteaderected tents, provided by thegovernment, on their property.Relief activities were coordinatedby the Ministry of Social Affairs

5

EERI SPECIAL EARTHQU.A:KE REPORT -DECEMBER 1992

concrete, illustrate properanchorage of walls to roofs, etc.

Valley. Specific recommendationsfollow.

3. For engineered buildings (newbuildings) designers and buildersmust avoid contributing to

vulnerability:

Geosciences

foundation svstems on soft soil,

for example, older buildings of

heavy masonry which lacked piles

tended to rotate and tilt with their

shallow foundations. (This was

partly due to the high undergroundwater table ~ 3.0 meters from the

surface. )

1 .The causative fault of the

October 12, 1992, earthquake re-

mains unknown for lack of surface-

breaking ruptures. Geophysicalsurveys could be performed to

identify any geological structures

that might be associated with the

earthquake.

DOOr construction materials

(aggregate, poor concrete mix,

some defective cement, unde-

formed reinforcing bars and ties,

hollow masonry, and clay tile and

mortar) ; 2. Seismological instrumentation

stations, both permanent and

portable, need to be upgraded to

modern digital seismographs that

are capable of recording a broad

spectrum of earthquake ground

motions.

DOOr overall construction and

workmanshiD; and

Doorlv enforced code coupled with

poor maintenance and defective

plumbing and sewage systems.3. Strong motion instrumentationis needed in the Cairo area tomeasure earthquake ground mo-tions (characteristics) for appli-cations in engineering design andthe identification of areas prone toground motion amplification,liquefaction, etc.

-avoid building irregularities,abrupt changes in stiffness, andweak/soft stories;

-provide for demand imposed onshort columns by framed deepspandral beams, and designingand installing necessaryreinforcing details;

-give appropriate attention tobeam-column joints, and theneed for stable ductile behaviorin the immediate regions nearthe joints;

-pay special attention to precastand prestressed constructionand the need for good continuitydetails at the joints; and

-define quality assurance andquality control programs fordesign, construction materials, I

and workmanship.

Type III buildings are historicstructures, such as mosques,churches, and monuments. Themost affected areas were old Cairowith its old stone and unreinforcedbrick bearing buildings, historicmosques, and Coptic churches.Many of these structures sustainedprevious damage from the August1847 earthquake.

4. For existing hazardous buildingsa national effort to assess risksand a hazard reduction plan tomitigate life safety threats areneeded. Additionally, attemptsshould be made to provide follow-up practical seminars in Egypt forevaluation, repair, and retrofit of

buildings.

Structural Engineering

1. Earthquakes have caused

damage in the vicinity of Cairo

since Biblical times and un-doubtedly will occur in the future,

The best preparation for this

earthquake hazard is the develop-

ment and enforcement of a code

for building design that accounts

for 1he expected ground motions.

Damage included tilted, damaged,and toppled minarets in mosques;cracks at the corner stone ofmasonry arches; cracking andminor failure in stone walls; anddistortion and failure of unsup-ported stone parapets. One largedome was severely damaged, andpartially collapsed .

5. Courses in earthquake engi-neering related subjects should befurther emphasized in universitycurricula.

AcknowledgementGeoscience and StructuralEngineering Conclusions andRecommendations Participation in this effort by T .

Topozada of CDMG, and Paul

Thenhaus and Bob Sharp of USGS

is highly appreciated .The earthquake surprised mostpeople, but was not without pre-cedent in Egypt and the surround-ing area. The earthquake shouldserve as a stimulus to efforts toassess the earthquake risk andquantify the hazard in high densityurban areas of the Nile River

2. For non-engineered buildings(mostly housing), the constructionpractices and the repairs orstrengthening schemes must bedeveloped to take into account theneeds of the people and theresources available. Guidance andeducation could be provided withsimple and understandable postersshowing "what to do," "what notto do," "how to do it," and "whereto go." These posters coulddemonstrate the dangers causedby parapets, show how to mix

4

EERI SPECIAL EARTHQUAKE REPORT -DECEMBER 1992

;r{Ypes of Building

\\):;onstruction and Structural

Response

For the purposes of this report,buildings in the affected area havebeen divided into three types.

Type I Buildings have very littleengineering and no seismicresistant systems and includestructural systems and materialssuch as:

-adobe with wood floors androofs,

-old stone masonry with woodand steel floors and roofs,

-brick (unreinforced) masonrywith wood, steel, and reinforcedconcrete floors and roofs, and

-reinforced concrete skeletonswith unreinforced masonry infillwalls (Iow-rise, 2-5 stories) .

Old Cairo -Heavy damage to stone bearing wall buildings with unanchored woodroofs

masonry infill above the second orthird level, but with ground floorand mezzanines of greater heightand with no masonry infill. (Manylower level modifications are doneas afterthoughts without anyevaluation of seismic force anddrift demands, and consequentlywithout any proper shear orconfinement reinforcement.)

In general, reinforced concreteframed buildings with unreinforcedmasonry infill performed well inthis earthquake.

The damage observed in these

,ypes of buildings can be cate-

gorized as follows:

Type II buildings encompassengineered mid- and high-risebuildings. Buildings of this type inthe affected area included:

reinforced concrete systems with

deeD sDandrel beams and short

columns without appropriate shear

reinforcement;

-reinforced concrete framed

buildings with unreinforced

masonry infill,

-reinforced concrete buildings

with reinforced concrete shear

walls (site cast or precast),

-precast concrete and pre-

stressed beam/column systems,

-a very few partially ductile

moment resisting concrete

framed buildings, and

-a very few steel buildings.

excessive overloadina couoled with

soft and weak stories at lower

~ due to illegal (not properly

engineered) additions. (In

Heliopolis, a 14-story structure

that was designed to be 8 stories

collapsed.)

-cracks and separation in thecorners of the walls due to lackof tie-beams,

-roof and wall separation due tolack of adequate anchorage (rooftimbers are typically not an-chored nor do they extend suffi-ciently over the width of thewalls; this problem is com-pounded by heavy storage onthe roof), and

-collapse of laterally unsupportedmasonry parapets and walls.

The damage observed in the con-crete buildings appears to bemainly from random/special cir-cumstances encompassing someof the following conditions:

inadeQuate reinforced concrete

detailinQ, such as column ties,

beam-column joints, location and

length of lap splices, development

length, etc.;

Obvious deterioration, varyingquality of brick and masonry block,and poor quality of mortar mix andplacement contributed to damagein some buildings. The structuresthat performed well were symme-trical, were of good quality con-struction, and were well main-

~ined. Thick walls with minimum~penings and small height to

thickness ratios contributed to lowstress levels.

hiahly irreaular stiffness

distribution in the structural

system, such as in high-rise rein-forced concrete buildings with

inaDDrODriate locations and DOOr

workmanshiD at column cold

~;

3

EERI SPECIAL EARTHQUAKE REPORT -DECEMBER 1992

very normal occurrence. The fol-lowing tabulation of aftershocksthrough October 22, 1992, wasprovided to the EERI Team by theHelwan Observatory:

of near-surface ground failure orcompaction in a restricted area inthe epicentral region. Consideringthe moderate size of this earth-quake and its depth, the lack ofsurface offset from the faultdislocation is not surprising .Settlement of up to 1.5 m wasreported along the main north-south highway west of the NileRiver near the village of ManshiatFadil. East of the highway at thislocation, soil liquefaction features(sandblows) were noted in thecultivated fields.

MaQnitude Number of Events

0-1.9 420

2.0- 2.9 210

3.0- 3.9 15

4.0- 4.9 25.0- 5.9 1 *

Manshiyat-Fadil and represents theepicentral intensity of the October12 earthquake. Intensity VIIIcorresponds to the fall of ordinarymasonry walls and complete col-lapse of adobe structures. Thedegree of this type of damage inmany structures in Manshiat Fadiljustifies this level of intensity.Furthermore, it is the only locationwhere liquefaction was observed.Intensity VII was common in manyvillages of the Nile Valley andgenerally corresponds to cracks inordinary masonry walls and the fallof adobe walls and masonry para-pets that were not reinforced.

*Main shock of October 12, 1992

(Note: Other aftershocks have

occurred since October 22 when

these data were compiled. )

Ground Motion -Valley ofthe Nile Site ResponseThe EERI team investigators see

nothing unusual concerning theaftershock sequence and feel thatit is highly unlikely that theearthquake of October 1 2 was aprelude to an even larger event inthe near future.

The eleven strong-motion acceler-ographs in Egypt (some at theHelwan Observatory), part of thehigh Aswan Dam Project, did nottrigger because they were not setup for strong ground motion re-cording in the vicinity of Cairo.Thus, the October 12 earthquakeseismic motion was not recorded.

Observations of Earthquake

Intensity

The liquefaction features werenoted near the villages thatexhibited the highest degree ofdamage and probably defined thegeneral area of strongest high-frequency ground motion. Al-though liquefaction was restrictedto a small area in this earthquake,it is likely that most areas of theNile River Valley are susceptible tothe phenomena of liquefaction andmuch larger areas could beaffected by the occurrence of a

larger magnitude earthquake.

Aftershocks following an earth-

quake of the size of the October

1 2 earthquake are common and a

The highest intensity observed bythe team was Modified MercalliIntensity VIII in the village of

However, it is the writers' opinion,from the nature of the observeddamage, that significant amplifica-tion of earthquake motion probablyoccurred in the alluvial deposit ofthe Nile Valley around Cairo andvicinity. The filtering of the high-frequency and acceleration spikesproduced an amplified motion withlong period characteristics at thedeep alluvial sites. This phenome-na at moderate earthquake levelsand with short duration accountsfor the very low damage levels inthe large inventory of stiff unrein-forced masonry infill buildings.

I

It is suggested that a strong-motion array in Cairo and its vi-

Icinity, as well as other seismicallyactive regions of Egypt, be orga- .1nized to record, assess, and estab.lish attenuation and amplificationcharacteristics of the Egyptian

earthquakes.Mixture of stone and mud brick construction

2

EERI SPECIAL EARTHQUAKE REPORT -DECEMBER' 992

L12, 1992

~ TELOn October 12, 1992, at 3: 10p.m. local time, an earthquake ofMb 5.9 (M. 5.4) occurred nearCairo, Egypt, that resulted inapproximately 500 deaths, thou-sands of injuries, the collapse of afew structures, and damage tomany structures in the Cairometropolitan area (population12,000,000).

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.~EERI dispatched a team of earth-quake engineers and scientists toinvestigate the effects of thisevent. Team members were NabihYoussef, structural engineer, TeamLeader; Samy Adham, structuralengineer; Mehmet Celebi, USGS;and Josephine Malilay, Centers for

--Qisease Control. The following}eport contains information fromthe preliminary report filed by theteam.

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~.Si-..~"\..,,- .-Historic Seismicity

Epicenters of earthquakes in 1992 south of Cairo, 1981 south of A swan, and1969 in the northern part of the Red Sea are shown. Historical earthquakes inarea A (north of Alexandria), area B (near Cairo), and area C (near Faiyum) arementioned in the text.

30.05°N and longitude 31 .18°E, asreported by the U.S. GeologicalSurvey, at 3:10 p.m. local time. Apreliminary focal mechanism pro-duced by Harvard Universityshowed normal (extensional)faulting at a depth of approxi-mately 24 km. A search for sur-face faulting by the EgyptianGeological Survey and MiningAuthority, the U.S. GeologicalSurvey Team, and this EERI Teamdiscovered no surface faultingfrom the earthquake. However ,tension cracks were observed insemi-consolidated alluvium thatmight be related to a small amount

This earthquake came as a surpriseto the world community, despitethe fact that Egypt and surround-ing regions have a history ofrecorded earthquakes that dateback to 2200 B.C. A great num-ber of these earthquakes areunknown to the seismologistsbecause their descriptions arescattered in various historical and

geographical manuscripts.

Damaging earthquakes that haveoccurred near the Nile Valleysurrounding Cairo for the areas ofAlexandria, Faiyum, and the Deltanear Cairo include 1955 (M. 6.7),1870, and 1690 earthquakes in

'\he Alexandria-Rashid area; 1 847Jnd 1303 earthquakes near Fai-

yum; and 1754, 1111, and 2200B.C. earthquakes in the Nile Deltanear Cairo.

The Red Sea area is also seis-mically active, but is lightlypopulated compared to the areasurrounding the Nile Delta. Themost recent damaging earthquakein this area occurred in 1969 (M.6.8), near Shadwan Island offshorefrom Gem sa and Hurghada, 380km southeast of Cairo. Threepeople were killed, 15 injured, and32 buildings were destroyed.

Geological and SeismologicalObservations~\

The earthquake of October 12,1992, was located at latitude

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