6. Estimation of Macroseismic Intensity
6. Estimation of Macroseismic Intensity
6.1 Macroseismic Intensityfrom the Building Damage

deducedY. Hisada and K. Meguro

EMS98 is a macroseismic scale proposedby the European Seismological Commissionof IASPEI (International Association ofDuring
the2001
Gujarat,India,
earthquake, strong motion records were notavailable in the damaged area except
Ahmedabad (see Fig. 6.1; Roorkee University,
Dept. of Earthq. Engng, 2001). Thus, inSeismoloy and Physics of Earth’s Interior) in1998, which was modified from the MSKscale (1964) to be applicable to variousmodern structures. Similar to the MSK scale,
EMS98 defines the building vulnerability
classes from A to F, as shown in Fig.6.2. It

order to estimate the strong motion, we
carried out building damage surveys, andestimated a MSK intensities on the basis ofEuropean Macroseismic Scale 1998 (EMS98).
For this purpose, the following five groups
carried out the surveys to obtain thealso classifies building damage into Grade 1to 5, as shown in Fig.6.3. The intensity was
deduced from the numbers of damagedbuildings for various damage grades andvulnerability classes, as shown in Table 6.1.
We classified the vulnerability of thebuilding damage data.
Group 1: K. Meguro, F. Uehan, and P. K.
Ramancharla (Univ. of Tokyo)
Group 2: Y. Hisada (Kogakuin Unv.)
Group 3: T. Toshinawa (Meisei Univ.)
Group 4: Y. Hayashi and S. Sawada (Kyotobuildings in Gujarat as follows (see Fig.6.2).
First, the masonry houses are classified into
Type 1 to 3. Type 1 represents typicaltraditional houses, which are made ofrubble stones with mud mortar and wooden
roofs (see Photo 6.1). This type isUniv.) and S. Pareek (Nihon Univ.)
Group 5: K.Venkataramana (KagoshimaUniv.), D. K. Paul, and R. N. Dubey(Roorkee Univ.)Type 1
Type 2Type 3

RCFig. 6.1 The Gujarat state and the epicenterof the Gujarat earthquake (USGS, 2001)

Fig.6.2 Vulnerability classes according tobuilding types by EMS98

1

6. Estimation of Macroseismic Intensity
Table 6.1 Relation between the MSK
intensity and the numbers of damagedbuildings for various vulnerability classes
and damage grades (EMS98)
Intensity damage Class A Class B Class C Class DⅤG1a few a few
ⅥG1m a n y m a n y a few
G2a few a few
Ⅶ
G1a fewG2
m a n y a few
G3
m a n y a few
G4a few
Ⅷ
G2
m a n y a few
G3
m a n y a few
G4m a n y a few
G5a few
G1
Ⅸ
G2
many
G3
m a n y a few
G4m a n y a few
G5m a n y a few
Ⅹ
G2
G3
many
G4
m o s t m a n y a few
G5
m o s t m a n y a few
11
G2
G3
G4
most manyG5m o s t m a n y a few
12G5
All
AllAllmostcategorized as vulnerability Class A. Type 2
represents relatively new houses, which are
made of simple stones or manufactured
blocks with wooden roofs (see Photo 6.2),and are classified as vulnerability Class B(Fig.6.2). Type 3 are newer houses, whose
walls are similar to type 2, but have RC
roofs and/or RC floors (see Photo 6.3). They
are classified as vulnerability Class C(Fig.6.2).
On the other hand, typical RC buildingsin Gujarat are made of RC frames with
un-reinforced concrete blocks. Since theearthquake resistant design code is notmandatory in India, they are classified asvulnerability Class C (see Fig. 6.2). However,Fig.6.3 Classification of damage grade formasonry (top) and RC (bottom) buildings
by EMS98

during the survey, we found that theda mage grades were clearly different
between buildings with and without pilotis(see Photo 6.4 and 6.5). RC buildings withpilotis were found extremely weak, i.e.

2

6. Estimation of Macroseismic Intensity

Photo 6.1 Type 1 masonry house (Class A)
Photo 6.4 RC building without piloti(Class C)

Photo 6.2 Type 2 masonry house (Class B)

Photo 6.5 RC building with piloti (originallyclassified as Class C, but in reality weaker
than Class C)

equivalent to Classes A to B. Actually,buildings for each type, and additionalcomments. After the survey, we compiled all
the data from the five survey groups, andestimated the intensity in each city or village
using Table 6.1. The number of damaged

almost all damage in Ahmedabad wasconcentrated on the buildings with piloti.
Therefore, we take into account these effects
when we estimate macroseismic intensity.
During the survey, we used the intensity
survey sheet shown in Fig.6.4. The collectedbuildings in each category in the table isclassified into few (0-20 %), many (20-60 %)or most (60-100 %). Here, we assumed thatthe average damage grades correspond tothe category “many” in Table 6.1, andestimatedthecorresponding
MSK

data were the date and time of theobservation, the name of city or village, thelocation (latitude and longitude using GPS),the average damage grade and theapproximate numbers of investigatedintensities.
Fig.6.5 shows the estimated intensity
contours using only the damage data ofbuildings Type 1 (Class A). Although we seesome differences in grade in the same

Photo 6.3 Type 3 masonry house (Class C)

36. Estimation of Macroseismic Intensity
MSK Intensity Survey Sheet for the 2001 Gujarat, India, Earthquake
Name of Investigator:
Village

Location

ID Date Time or City
Name

Latitudedeg

minAve. Damage Grade & Apprx. Num. for Various Type of Build.
Longitude

sec

deg

min

Masonry*2)

sec Type 1 Num

*2)

*3)

RC Num*2)

Type 2 Num*2)Type 3 Num

CommentsPicture ID12345678910*1) Majority (Average) Damage Grade: 1 (G1:Negligible to Slight), 2 (G2:Moderate), 3 (G3:Substantial to Heavy), 4 (G4:Very Heavy), and 5 (G5:Destruction)*2) Approximate Number of buildings you watched in the village or city (ex 1; log-scale number, 1+, 10+, 100+, …), (ex 2; ○: majority, △: minority, ×:few)*3) Masonry Type 1: Buildings in rubble stone, fieldstone and/or adobe (usually with mud mortar)
Masonry Type 2: Buildings in simple stone, brick or concrete block (usually with cement mortar)
Masonry Type 3: Buildings in Type 1 or 2 with lintel band and/or RC floors

Fig.6.4

Fig.6.5

MSK intensity sheet based on EMS98

MSK intensity contours using the damage data of Type 1 buildings

villages between different groups, thevillages/cities with the highest damages (G5)
are concentrated around the epicentral area,

and the areas with smaller grades scatter
into circumferences. In Figs. 6.5 to 6.8, weused thicker lines in the contours with4

6. Estimation of Macroseismic Intensity

Fig.6.6

MSK intensity contours using the damage data of Type 2 buildings

Fig.6.7

MSK intensity contours using the damage data of Type 3 buildings

56. Estimation of Macroseismic Intensity

Fig.6.8 MSK intensity contours using the damage data of RC buildings

Fig.6.9 MSK intensity contours using all the data

6

6. Estimation of Macroseismic Intensity
higher grades because they are probably
more reliable; damage grades G4 and G5 areeasily detected visually, but this is not thecase of G1 and G2. Similarly, Figs. 6.6, 6.7,
and 6.8 show the estimated intensity

biases. The damage information is usually
exaggerated at bigger cities. On the otherhand, Fig. 6.11 shows a MSK intensity map
by Narula and Chaubey (2001) on the basisof field survey data. There are similarities

contours using only the Type 2 (Class B),
Type 3 (Class C), and RC (Class C or less forstructures with piloti) data, respectively. The
similarity of contours suggests the overall
reliability of the data. Finally, Fig.6.9 shows
the integrated intensity contours using all

between both MSK maps, such as elongating
contours along the northeast to southwest
axis. However, there are also differencessuch as the location of the region withintensity 10. For instance, the map ofNarulaandChaubey(2001)
locatesthe data from Figs. 6.5 to 6.8.
We shall compare our intensity map
shown in Fig.6.9 with the other existing
intensity maps. Fig.10 shows a MM intensity
map by Martin and Hough (2001), which
was estimated using media information.

Bhachau out of intensity 10 area and Raperis in. Our proposal map suggests exactly
opposite. Photo 6.6 and 6.7 show typicaldamages to RC buildings in Bhachau andRaper, respectively. Almost all RC buildingsin Bhachau suffered severe damage, while

Although there are similarities between bothmaps, there are also distinctive differences.
In particular, the map of Martin and Hough(2001) shows the highest intensity aroundBhuj, rather than around the epicentral
area. This is probably because of media

only moderate damage in RC buildings wereobserved in Raper. Therefore, we believe that
ourintensity
map
represents
morerealistically the macroseismic intensity inthe epicentral area.

Fig.6.11 MSK intensity using field survey
data (Narula and Chaubey, 2001)

JMAMMMSK
Acc

Fig.6.10 MM intensity using media data
(Martin and Hough, 2001),

Fig.6.12

Comparison among the JMA, MM, andAcc intensities, and maximum acceleration
MSK7

6. Estimation of Macroseismic Intensity
7.5, which is close to Mw=7.6 reported by
USGS. This agreement also supports thevalidity of our results.
Acknowlegement
This building damage survey was possible
with the collaboration of Drs. F. Uehan, andP. K. Ramancharla (Univ. of Tokyo), T.
Toshinawa (Meisei Univ.), Y. Hayashi and S.
Sawada (Kyoto Univ.), K. Venkataramana(KagoshimaUniv.),
H.
Murakami

Photo 6.6 Damage to a RC building in
Bhachau(Yamaguchi Univ.), S. Pareek, (Nihon Univ.),
D. K. Paul, R. N. Dubey, and A. Kumar(Roorkee Univ.).
References
U. S. Geological Survery, 2001
http://neic.usgs.gov/neis/eqhaz/010126.html
Government of India, 2001
http://www.ndmindia.nic.in/eq2001/eq2001.html
Roorkee University, Dept. of Earthq. Engng,2001
http://vision.rurk.iu.ernet.in/depts/earthquake/bhuj
European Macroseismic Scale 1998 (EditorG. Grunthal), 1998
S. Martin, and S. Hough, Earthquake inIndia, January 26, 2001, Magnitude 7.7,
Intensity Distribution as compiled from
Newspaper Accounts

Finally, Fig. 6.12 shows a comparison of

http://neic.usgs.gov/neis/eqhaz/010126_int.html
P. L. Narula, and S. K. Chaubey, 2001,
MACROSEISMIC SURVEYS FOR THE
BHUJ (INDIA) EARTHQUAKE OF 26THJANUARY
http://www.nicee.org/NICEE/Gujarat/narula.htm

the JMA, MM, and MSK intensities, andmaximum accelerations. We can estimate
the JMA magnitude using the empiricalrelation (Chronological Scientific Tables,1996)
M=log(S5)+3.2,

Architectual Institute of Japan, 1999,
Report on the Damage Investigation of the1992 Turkey Earthqauke
Chronological
ScientificTables,
1996,
National Astronomical Observatory (ed.),Maruzen Co., Ltd, p817, 1996

where S5 is the area with intensity larger
than JMA intensity 5. In our proposed
intensitymap(Fig.
6.9),
theareacorresponding to JMA intensity 5 or higher
is about 21,500 km2. Thus, we obtain M≒

Earthquake Information Center, 2001, EIC
Seismology Note, No.98 Jan.26, '01 (rev.
01/01/27) the University of Tokyo
http://kea.eri.u‑tokyo.ac.jp/EIC/EIC̲News/010126.html

Photo 6.7 Damage to a RC building inRaper8