     

Bull. Earthq. Res. Inst.
Univ. Tokyo
Vol. 13 ,**. pp. 2+ῌ3-

Building Damage and Seismic Intensity in Bam City
from the ,**- Bam, Iran, Earthquake
Yoshiaki Hisada+*, Akihiro Shibaya+ and M. Reza Ghayamghamian,+,

Dept. of Architecture, Kogakuin University
International Institute of Earthquake Engineering and Seismology

Abstract
An investigation is carried out on earthquake damage to 2-3 buildings in and around Bam City,and seismic intensities, using European Macroseismic Scale +332 (EMS32), are estimated. The
northern and eastern sides of Bam City show higher damage rates (more than 2*ῌ), than thesouthern and western sides (,*ῌ less). Combining the results and the vulnerability classes ofvarious building types, the estimated MSK intensities are higher (up to XI) at the northern andeastern sides, and lower (down to VIII) at the south and west sides.

Key words ῌ ,**- Bam earthquake, earthquake damage, seismic intensity, European Macroseismic
Scale +332 (EMS32)+.

Introduction

city. In this paper, we summarize various types of

On December ,0, ,**- at */ : /0 (local time), a de-building damage, and estimate seismic intensities

vastating earthquake with a magnitude of Mw 0.0

using the data collected.

(USGS, ,**-), 0./ on the Richter scale, occurred at(,3.*+N, /2.,0E), +* km, southwest of Bam city in,.

Building Damage in Bam City and Strong Ground

Kerman province, southeast Iran (IIEES, ,**-), as

Motionsshown in Fig. +. It is estimated that more than ,0,***Figure , shows maps of Bam and Baravat cities,

people were killed, -*,*** injured, and up to 1/,0** left

together with the Bam fault, the locations of thehomeless. About 2/ῌ of the housing and the infra-

strong motion station of Building and Housing Re-

structure were destroyed (UN O$ce, ,**.). The United

search Center (BHRC) of Iran, and 2 acceleration

Nations (UN) estimates that the number of people

stations of IIEES for recording aftershocks.

a#ected by the loss of economic activity and damage

ﬁgure also shows an earthquake damage map, whichto property and infrastructure is up to ,**,*** (UNwas drawn from aerial photos (National Carto-

O$ce, ,**.). To investigate seismological character-graphic Center of Iran, ,**-). The eastern side of Bam

istics and earthquake damage, a Japanese reconnais-

city, which is closer to the Bam fault, shows higher

sance team was dispatched to Bam City, with grand-

damage rates than the western side of the city. The

in aid for scientiﬁc research from Monbu-Kagaku-

Bam fault is considered to be the causative fault ofsho (Japanese Ministry of Education, Culture, Sports,

the Bam earthquake, even though the epicentral area

Science and Technology), Architectural Institute ofof the earthquake is probably south of the city

Japan (AIJ), and Japan Association for Earthquake(IIEES, ,**-).

The

Engineering (JAEE). The reconnaissance was car-Figure - shows strong motion records and theirried out in collaboration with International Instituteresponse spectra at the Governmental O$ce in Bamof Earthquake Engineering and Seismology (IIEES)

city (see the location of the station in Fig. ,). Figuresof Iran. As members of the team, we investigated- (a) and (b) show accelerations and velocities. The

more than 2** damaged buildings in and around Bam

most interesting characteristic of the record is the* e-mail : hisada@cc.kogakuin.ac.jp (Nishi-Shinjuku +ῌ,.ῌ,, Tokyo +0-ῌ2011, Japan)81

Y. Hisada, A. Shibaya and M. Reza GhayamghamianFig. +.

Fig. ,.

Map of Iran and the ,**- Bam Earthquake.

Earthquake damage map of Bam and Baravat cities.῍ and the strong motion and aftershock stations.

ῌ 82 ῌ

Building Damage and Seismic Intensity in Bam City from the ,**- Bam, Iran, Earthquake(a) Acceleration.

(b) Velocity.

(c) Acceleration response spectra.

(d) Velocity response spectra.

Fig. -.

Strong motion records and response spectra at the Bam city.

long-period pulse in the EW (N2,E) components ofInvestigation of Building Damage in Bam City-.

the velocities. As can be seen in the response spectra-. +Building Type and Vulnerability Classin Figs. -(c) and (d), the dominant period of the pulse

To investigate building damage and seismic in-is about + to , seconds. Because the EW component

tensities, we followed the European Macroseismic

corresponds to the normal direction of the Bam fault,

Scale +332 (EMS32). EMS32 is a macroseismic scale

it seems that the pulse was generated by the forward

proposed by European Seismological Commission of

directivity e#ect (the killer pulse ; one of the near-International Association of Seismology and Physics

fault e#ects), which was widely observed in the vi-

of Earth’s Interior (IASPEI) in +332, which was modi-

cinity of seismic faults, such as the +313 Imperialﬁed from the MSK scale (+30.) to be applicable toValley and +33. Northridge, California, earthquakes,

various modern structures. Similar to the MSK scale,and the +33/ Kobe earthquake, Japan. During our

EMS32 categorizes the vulnerability classes of build-investigation, we found that most of the tilted build-ings from A to F, as shown in Table +. We classiﬁed

ings were inclined toward the west (i.e., see Photo ,),the building types in Bam city and their vulnerabil-which suggests the e#ects of a long-period pulse.

ity classes as follows :+.
ῌ 83 ῌ

Adobe : Vulnerability class A (See Table + andY. Hisada, A. Shibaya and M. Reza Ghayamghamian(a) Adobe (Vulnerability class A).

(b) Simple Masonry (Vulnerability class B).

(c) Masonry with Steel Frame (Vulnerability class C).

(d) Masonry with RC Frame (Vulnerability class D).

Photo +.

Adobe houses and masonry, and their vulnerability classes.

Photo + (a) ; the weakest type of building, con-0.

made of moment-resistant RC frames)

structed from earth bricks and clay mortar),.

EMS32 also classiﬁes damage to buildings into the

Simple masonry : Vulnerability class B (SeePhoto + (b) ; the second weakest type of building,-.

following Grades + to /.

constructed from manufactured bricks without

Grade + : Negligible to slight damage

reinforcements, and cement mortar)

Grade , : Moderate damage
Grade - : Substantial to heavy damage

Masonry with steel frame : Vulnerability classC (See Photo + (c) ; the building made of manu-

Grade . : Very heavy damage

factured bricks and cement mortar, with rein-

Grade / : Destruction
It should be noted that it is not easy to generalize

forcements of steel frames)..

/.

RC frame : Vulnerability class D or E (building

Masonry with RC frame : Vulnerability class D

the relation between building type and vulnerability(See Photo + (d) ; building made of manufactured

class. For example, simple masonry houses (Class B)

bricks and cement mortar, with reinforcements

in old areas of the city (i.e., Station Nos. +, ,, and 2)of RC frames)

seemed to be much weaker than those in new areas

Steel frame : Vulnerability class D or E (Seeof the city suburbs (i.e., Nos. -, 0, and 1). Many of the

Photo , ; building made of moment-resistant steel

former houses seemed to be vulnerability Class A,

frames)rather than class B, whereas some of the latter houses
ῌ 84 ῌ

Building Damage and Seismic Intensity in Bam City from the ,**- Bam, Iran, Earthquake

could be Class C. Another example is the case ofdamage at 2 stations installed for recording after-

masonry with steel and RC frame ; construction

shocks by IIEES. Table , shows a list of the stations,skills, especially welding of steel for columns, beams,

their locations, and numbers of buildings investi-

and braces, were relatively poor in old areas com-

gated in each area. For maps of Bam city, we used

pared to those in new areas. We do not have anysatellite images of Quick Bird, whose resolution ismore detailed or quantitative information, therefore,

about / m and is su$cient to identify each house

we use the simpliﬁed categorizations mentioned
above.
-. ,Investigated Areas and Overall Results

As shown in Fig. ., we investigated building(a) Moment-resistant steel frame building.
Photo ,.

Table +.

(b) Close-up of the column-beam connection.

Moment-resistant steel frame building (under construction).

Vulnerability class European Macroseismic Scale +332 (EMS32).

ῌ 85 ῌ

Y. Hisada, A. Shibaya and M. Reza Ghayamghamian(Kosugi Lab., ,**.). The research group of Tokyo

the buildings are simple masonry, and about ,*ῌ areTech. Univ. and Asia Air Survey kindly provided us

adobe and the masonry with steel frames. There arewith the images, and GIS-based street and housing

few masonry with RC frame and moment frame

maps, as shown in Figs. ., 0, and 1. In addition, theybuildings. From Fig. / (b), most of the adobe build-provided us with change detection maps before andings were completely destroyed (Grade /), and theafter the earthquake (Kosugi Lab., ,**.), which wereratios of Grades / and . accordingly decrease withvery useful to ﬁnd damaged areas during the investi-

higher vulnerability classes, that is, from adobe (vul-gation.

nerability class A) and simple masonry (class B) to

Table , and Fig. / show the total numbers ofmasonry with steel and RC frames (class C and D).

buildings investigated, and the damage grades for

Even though the numbers are not large, it is evident

each building type. From Fig. / (a), more than half ofthat engineering buildings (steel and RC moment

Table ,. The aftershock stations and the number of the buildings investigated around the stations.
(A : adobe, M : simple masonry, MS : masonry w. steel, MRC : masonry w. RC, S : steel frame, RC : RC frame).

Fig. ..

Map of Bam city and the eight investigated areas (drawn from satellite image ; Kosugi, Lab., ,**.).

ῌ 86 ῌ

Building Damage and Seismic Intensity in Bam City from the ,**- Bam, Iran, Earthquake(a) Number of each building type (Total Number῍2-3).

(a) Number of each building type (Total Number῍2-3).
Fig. /.

Total numbers and damage grades of investigated buildings.

frame) su#ered little damage compared to non-simple masonry buildings (Class B) are also Grade /,engineering buildings.

which suggests the intensity may approach XI.

-. -Building Damage and Estimation of Seismic

Numbers of other types of building are insu$cient toIntensity in Each Area

estimate intensity. Thus, we estimate MSK intensity

Next, we discuss damage in more detail aroundin this area as X to XI.

the 2 stations, and evaluate their EMS32 intensities.

Figure 0 (b) shows a table and a map of buildings

Table - shows relations among vulnerability classes,

investigated around station ,. This area is located indamage grades, and intensities.

the old city of Bam, including the main streets. Thus,

Figure 0 (a) shows a table and a map of buildings

many of the buildings are old commercial buildings,

investigated around station +. This station is locatedwhich are mostly masonry with steel frame. Almost

at the northeast side of Bam city south of Arge Bam

all of the adobe houses (Class A) were completely(see Figs. , and .). Houses in this area seemed to be

destroyed (Grade /), suggesting EMS32 intensity ofold. All of the adobe houses (Class A) were destroyed

more than X. Many simple masonry buildings (Class(Grade /), which indicates the EMS32 intensity isB) and masonry buildings with steel frames (Class C)

more than X from Table -. More than half of theare Grade /, and most of the simple masonry build-ῌ 87 ῌ

Y. Hisada, A. Shibaya and M. Reza Ghayamghamian
Table -.

EMS32 intensity scale using damage grade and vulnerability class.

ings with steel frames are more than Grade ., which

which also indicates the intensity may be IX to X. In

suggests that the intensity might approach XI.

addition, most of masonry with steel frame buildings

Therefore, we estimate MSK intensity in this area as(Class C) are Grade -. Therefore, the MSK intensity

X to XI.

in this area is estimated to be around X.

Figure 0 (c) shows a table and a map of buildings

Figure 0 (e) shows a table and a map of buildings

investigated around station -. This station is locatedinvestigated around station /. This area is located at

in a western suburb of Bam city, and the houses inthe east end of Bam city close to the Bam fault, andthe area are relatively new. Thus, there are no adobe

the houses are relatively old. Almost all of the adobe

houses.

Even though we classify most houses ashouses (Class A) are Grade /, suggesting an intensity

simple masonry, as shown in the table, it was notof more than X. Most are simple masonry (Class B)

easy to judge them only from appearances, because

and many masonry with steel frame buildings (Class

most had minor damage. Thus, some may have steelC) are Grade /, which suggests the intensity mightor RC reinforcements. From the table, a few simple

approach XI. Therefore, the MSK intensity in thismasonries (Class B) are Grades / and ., and many arearea is estimated to be X to XI.

Grades - and ,, which suggests intensity may be VII
to IX.

Figure 0 (f) shows a table and a map of buildings

A few masonry with steel frame buildings

investigated around station 0. This station is located(Class C) are Grades . and -, and many are Grade ,,south of Bam city, and the houses are relatively new,which suggests the intensity may be VIII to IX.

with no adobe houses. Many simple masonry build-Thus, we estimate MSK intensity as VIII to IX.

ings (Class B) are from Grade - to /, which suggests

Figure 0 (d) shows a table and a map of buildings

the intensity might be VIII to X. Many masonry withinvestigated around the station .. This area is be-

RC frame buildings (Class D) are Grades . and -,tween stations , and -, and the houses are relatively

which suggests the intensity might be X to XI. Evenold. All of the adobe houses (Class A) are Grade /,though the number of buildings is not large, mostsuggesting an intensity of more than X. Many sim-

steel frame houses (Class D to E) are Grade ,, which

ple masonry buildings (Class B) are Grades . and /,suggests the intensity might be around X. Conse-ῌ 88 ῌ

Building Damage and Seismic Intensity in Bam City from the ,**- Bam, Iran, Earthquake

quently, we estimate MSK intensity in this area to besity is more than X. Many simple masonry buildings

around X.

(Class B) are Grades - to /, which also suggests the

Figure 0 (g) shows a table and a map of buildings
investigated around the station 1.

This station isintensity may be VIII to X. Many masonry with steel
frame buildings (Class C) are Grade -, and a few oflocated near the center of Bam city, where the strong

them are Grade ., which also suggests the intensity

motion station is located. This area includes mainmight be IX. Therefore, we estimate MSK intensity

streets, and their commercial buildings seemed to bein this area to be IX to X.

relatively new, and the residential houses seemed
relatively expensive and well constructed.

Figure 0 (h) shows a table of buildings investi-

Mostgated around station 2. A street map is not available,

adobe houses (Class A) are Grade /, suggesting inten-

because this station is located in Baravat City, east of

Fig. 0. Tables and maps of investigated buildings around the eight stations.
A : adobe, M : simple masonry, MS : masonry w. steel, MRC : masonry w. RC, S : steel frame, RC : RC frame.

ῌ 89 ῌ

Y. Hisada, A. Shibaya and M. Reza Ghayamghamian

Bam city. The buildings in this area seemed to be

estimated MSK intensities in the 2 areas, together

relatively old. Even though the number of adobe

with the damage map, which was estimated fromhouses (Class A) is not large, many are Grades . andaerial photos independently (National Cartographic/, suggesting intensity is around IX. Many simple

Center of Iran, ,**-).

masonry buildings (Class B) are Grades . to /, whichratios between our results and the damage mapsuggests the intensity may be IX to X. Thus, theshows excellent agreement ; the north and east sides

MSK intensity in this area is estimated to be IX to X.

of Bam city, whose buildings are relatively old, show

The comparison of damage

very high damage rates, whereas the south and west
Conclusions

sides, whose buildings are newer, show much lower

Figure 1 shows the rates of buildings with more

rates. Combining these damage rates and vulnerabil-than very heavy damage (Grades . and /), and the

ity classes of building types, we estimate the MSK..

Fig. 0.

(Continued)

ῌ 90 ῌ

Building Damage and Seismic Intensity in Bam City from the ,**- Bam, Iran, Earthquake

intensity to be higher, X to XI, at the north and east

Acknowledgements

sides, and to be lower, VIII to X, at the south and west

We thank Mr. G. Reza Nouri and Masud M. Ahari

sides. An independent study shows the MSK intensi-

of IIEES for their help during the investigation. This

ties in a wider area in and around Bam City are VIII

research was carried out with a grand-in aid for

to IX , which also validates our estimates. In futurescientiﬁc research from Monbu-Kagaku-sho (Japa-

studies, we plan to construct vulnerability curves ofnese Ministry of Education, Culture, Sports, Sciencevarious building types, by combining our results andand Technology), Architectural Institute of Japan,

the strong ground motions, which may be simulated

and Japan Association for Earthquake Engineering

using aftershock records on the basis of Green’s em-(JAEE), in collaboration with IIEES (International

pirical function methods.

Institute of Earthquake Engineering and Seismol-,῍ogy) of Iran. The research group of the Kosugi Lab.

Fig. 0.

(Continued)

ῌ 91 ῌ

Y. Hisada, A. Shibaya and M. Reza GhayamghamianFig. 0.

(Continued)

ῌ 92 ῌ

Building Damage and Seismic Intensity in Bam City from the ,**- Bam, Iran, Earthquake

Fig. 1. Damage rates and estimated MSK intensities, together with damage map estimated from aerial
photos independently.῍.

of Tokyo Tech. Univ. and Asia Air Survey kindly
provided us satellite images of Quick Bird, and the
GIS-based street and housing maps.

We used thestrong ground motion records in Bam City under the
research contract between BHRC (Building And
Housing Research Center) and the JAEE team.
References
USGS, ,**-, http : //earthquake.usgs.gov/recenteqsww/Quakes/
uscvad.htm
IIEES, ,**-, Preliminary Report on Bam Earthquake, http : //www.iiees.ac.ir/English/eng_index.html
UN O$ce for the Coordination of Humanitarian A#airs,,**., Iran : Bam earthquake Revised Appeal No. ,//*Operations Update No. +-, ,. Jun ,**., http : //www.
reliefweb.int/w/rwb.nsf/.2*fa21-0b22bbc-c+,/0.f0**.c
2 ad / / a .3./-. ded ..+ a * fc +,/0 ebe **-++.2 f? OpenDocument
National Cartographic Center of Iran, BAMﬁnal_H_Big-.
exe, ,**-, http : //www.ngdir.ir/Downloads/Downloads.
asp?o#set῎*
Kosugi Lab. of Tokyo Tech Univ. and Asia Air Survey, ,**.,Jan ,*, ,**., Bam City Change Detection Result, http ://www -kosugi. pms. titech. ac. jp / media / ,**.*+,3 /,**.*+,3_e.htm
European Macroseismic Scale, +332, Editor G. Grunthal(Received February ., ,**/)(Accepted February ,+, ,**/)

ῌ 93 ῌ