On January 26, 2001, 

a M 7.7 earthquake 

struck the State of 

Gujarat in the northwest corner of India. 

Several teams of 

scientists traveled to 

the region to study 

what is now known as 

the Bhuj earthquake 

(named after the 

closest affected city). 

A few of these teams 

came from the Central 

and Eastern United 

States, with the 

specific objectives of 

learning lessons 

that they could apply 

directly to reducing 

earthquake hazards 

in their own cities 

and towns. 

Although geographically distant, the State of 

Gujarat in India bears many geological similarities to the Mississippi Valley in the Central 

United States. The Mississippi Valley contains 

the New Madrid seismic zone that, during the 

winter of 1811-1812, produced the three 

largest historical earthquakes ever in the continental United States and remains the most 

seismically active region east of the Rocky 

Mountains. Large damaging earthquakes are 

rare in ‘intraplate’ settings like New Madrid 

and Gujarat, far from the boundaries of the 

world’s great tectonic plates. Long-lasting 

evidence left by these earthquakes is subtle 

(fig. 1). Thus, each intraplate earthquake provides unique opportunities to make huge 

advances in our ability to assess and understand the hazards posed by such events. 

Figure 1. Close-up view of liquefaction taken several weeks after the Bhuj earthquake near the village of Umedpar. 

Shaking caused the saturated soils and sands to lose their strength and compact, raising the water pressure until 

water and sediment erupted on the surface as sandblows. As the salty water dries, a white salty crust is left behind. 

This part of the epicentral area, known as the Banni Plain, is adjacent to an inlet to the sea (the Great Rann of Kutch) 

that floods annually. The extremely flat topography suggests that the rates of geologic activity must be very low 

because high rates build mountains and other topographic relief. (Photo courtesy of Gary Patterson, Center for 

Earthquake Research and Information, Memphis, Tenn.) 

U.S. Department of the Interior 

U.S. Geological Survey 

U.S. Geological Survey Fact Sheet FS-007-02 

Why travel halfway around the world to study an earthquake? 

East meets Midwest: An earthquake in India 

helps hazard assessment in the Central United States 

March 2002 
71 ̊ 72 ̊

23 ̊N

24 ̊N

25 ̊N

71 ̊ 72 ̊

22 ̊N

2001 Bhuj epicenter

A

B

1819 'Alla Bund' epicenter Island Belt Fault

Kutch Mainland Fault

Katrol Hills Fault

Kutch rift boundary

Kutch rift boundary

68 ̊E 69 ̊E 0 ̊E 71 ̊E 72 ̊E

B

Aftershock Depths, in km 10

20

20 Kilometers

30

40

0

PAKISTAN

inferred 

mainshock 

fault

A

Figure 2. The New Madrid seismic zone

is defined by a z-shaped pattern of

earthquake epicenters (blue crosses).

Many lines of evidence suggest that this

pattern defines the major faults that

broke during the 1811-1812 earthquakes.

The vast majority of the earthquakes

shown here are much too small to be

felt and have been recorded by sensitive

instruments deployed in the early 1970s.

The earthquake activity roughly parallels

the Reelfoot rift, an ancient break in the

Earth’s crust. Millions of years ago the

crust began to pull apart, or rift, but

failed to break completely as happens

when new plate boundaries form.

Instead, a long linear zone of intense

faulting formed. Today the crust is being

compressed in the direction shown by

the arrows. Much of the seismic zone is

buried beneath the Mississippi embayment (darker green area), a trough filled

with sediments that may greatly amplify

earthquake shaking.

Figure 3. Shaded relief map of northwestern

Gujarat, showing the locations of the 2001

M 7.7 Bhuj and the 1819 Alla Bund earthquakes, which probably were events of similar size (stars). Both earthquakes occurred

in the Kutch rift, an example of a failed rift

that is now affected by stresses (arrows)

that act to compress it rather than pull it

apart. Known faults are labeled. Like the

New Madrid region, much of the region is

blanketed by thick sediments. No earthquake monitoring network existed in Gujarat

prior to the Bhuj event, but aftershocks

were recorded by temporary networks.

(Dots show aftershock locations; colors

indicate aftershock depths: red, deep;

green, intermediate; blues, shallow.) The

extreme compactness of the inferred mainshock fault (dashed rectangle) contrasts

with a typical earthquake on a plate edge,

such as the recent M 7.6 1999 Taiwan earthquake, which raised the surface 8 m and

broke the Earth's surface for almost 100 km

(approximately the length of the Island Belt

fault shown). 

Inset: Aftershocks viewed in cross-section,

along a line from A to B, reveal a southward

dipping fault. If projected to the surface, the

top of the fault (edge of the dashed rectangle on the map) does not correspond to any

mapped fault. (Figure from Paul Bodin,

Center for Earthquake Research and

Information, Memphis, Tenn.)

37 ̊N

36 ̊N

35 ̊N

Ohio River

MISSOURI

ARKANSAS

KENTUCKY

Memphis

Reelfoot rift

91 ̊W 90 ̊W 89 ̊W

TENNESSEE

Mississippi embayment

100 Kilometers

Reelfoot rift boundary

Reelfoot rift boundary

92 ̊W 88 ̊W

Mississippi River

7
Gujarat, India, have in common? 

What do the Central United States and 

The geologic settings of the New Madrid and 

the Bhuj earthquakes are ancient failed-rift 

zones (figs. 2, 3). Although both formed under 

very different geologic circumstances than exist 

today, they are zones of relatively weaker 

crustal rocks where earthquake processes may 

cause faulting to occur more easily than in surThe relationship of the New Madrid and Bhuj 

earthquakes to plate-tectonic motions remains a 

mystery. Although most earthquakes in the 

world occur in response to the relative motions 

of adjacent plates, both the New Madrid and 

Bhuj earthquakes occurred more than several 

hundred kilometers from the nearest plate 

boundaries. In New Madrid, sophisticated surveying techniques confirm a lack of relative 

motion across the region. Similar measurements 

are just being made in Gujarat, and preliminary 

evidence indicates that if there are relative 

motions, they are very, very slow. Thus, it 

seems that the energy released in these geologically frequent major earthquakes exceeds the 

energy supplied by plate-tectonic motions. We 

know that the level of stress in crustal rocks in 

intraplate regions is high, and it may be that 

these frequent earthquakes result from the 

release of energy from plate motions that has 

accumulated over long periods of geologic time. 

The effects of earthquakes are better understood 

than why and how they occur. By far the greatest cause of damage is related to the ground 

shaking associated with seismic waves emitted 

by earthquakes. Thick, soft sediments and soils 

amplify ground shaking. Poorly cemented sediments many hundreds of meters thick blanket 

much of both the Gujarat and New Madrid 

regions. When water saturated, sediments are 

also highly susceptible to a phenomenon called 

liquefaction, in which shaking causes the sediments to become fluidlike; they lose their ability 

to support structures. Liquefaction also results in 

fountains of sand and water erupting to the surface (figs. 1, 5). Both the Bhuj and the New 

Madrid earthquakes were accompanied by widespread liquefaction. 

Figure 4. Ground 

failure from the 

Bhuj earthquake 

most likely resulted 

from shaking, as the 

soil mass cracked 

and slid down the 

almost imperceptibly sloping ground 

surface. No permanent changes to the 

topography directly 

related to faulting 

have been identified. The flat terrain 

suggests that few 

shallow earthquakes have 

occurred here previously and (or) that 

the processes leading to frequent 

(geologically) large 

earthquakes have 

not been going on 

for very long. 

What can we learn? What have we already 

learned? 

Earthquakes affect much larger areas in the 

Central and Eastern United States than in the 

Western United States. Preliminary studies of the 

Bhuj earthquake show its reach to be very similar to those of the New Madrid earthquakes 

(background maps on page 1; modified from 

maps contributed by Susan Hough, 2001). This 

may reflect, in part, more efficient transmission 

of seismic waves in the colder, less faulted, older 

crust of plate interiors, relative to younger, hotter, and more fractured crust common along plate 

edges. However, a long-standing question is 

whether plate boundary and plate interior earthquakes themselves differ in some fundamental 

way, and whether these differences contribute to 

the profoundly greater extend of earthquake 

effects in plate interiors. Further study of data 

from modern seismic instruments for the Bhuj 

earthquake, which do not exist for New Madrid 

events, hold possible answers to these questions. 

rounding regions.


In both regions, large damaging earthquakes


happen more frequently than scientists would


expect based on the number of small and mod­


erate earthquakes. In Gujarat, there was a major


earthquake that broke a fault in 1819 and evi­


dence of another one about 800


years earlier. In the Central United


States, there is strong evidence of at


least two prehistoric earthquake


sequences similar to the 1811-1812


earthquakes, which shook the New


Madrid region in about 1450 and


900 A.D. The geologically short


time between large earthquakes (500


to 1,000 years) is surprising.


Generally, such short times between


large earthquakes are associated


with more frequent small and mod­


erate earthquakes than are observed


in either Bhuj or New Madrid. In


addition, neither region has the high


topography that is a hallmark feature


of regions elsewhere in the world


that host frequent large earthquakes


(figs. 4, 5).

For more information, 

contact: 

Joan Gomberg 

Eugene Schweig 

U.S. Geological Survey 

3876 Central Ave. 

Suite 2 

Memphis, TN 38152-3050 

901-678-4858 

gomberg@usgs.gov 

Graphic design and layout by 

Pamela Svendsen Detra 

and Eleanor Omdahl 

Astounding implications 

about the Bhuj mainshock have already been 

suggested from studies 

of its aftershocks (fig. 

3). Researchers began 

deploying instruments to 

record aftershocks of the 

Bhuj earthquake almost 

immediately after the 

January earthquake. 

Aftershocks generally 

outline the fault that 

caused the mainshock, 

but Bhuj aftershocks reveal faulting deeper 

in the lower crust than generally thought 

possible. The fact that the aftershocks occur 

in a very compact volume suggests a highly 

concentrated source of stress. These results 

are key to understanding how earthquakes 

work in environments like Gujarat and New 

Madrid. 

Surprisingly, faulting associated with the 

Bhuj earthquake stopped far below the 

ground surface, unlike most earthquakes of 

comparable magnitude. Although almost 200 

years have passed since the 1811-1812 New 

Madrid earthquakes, most evidence indicates 

that they did not break the surface. The 

faults that cause large earthquakes typically 

rupture the surface of the Earth, forming a 

visible scarp. In addition to telling us about 

how earthquakes work, the depths over 

which a fault breaks determine the types of 

seismic waves radiated and thus, how the 

ground shakes. Further study of the Bhuj 

earthquake may reveal the reasons why 

faulting stopped before reaching the surface 

and how this relates to the pattern of shaking. Faults not visible on the ground surface 

Figure 5. Sandblow deposits 

(light-colored spots) that erupted during the 1811-1812 earthquakes are still a common 

sight in farmers' fields of the 

upper Mississippi Valley. The 

interstate highway in the upper 

part of the photo provides 

scale. The flat topography 

resembles that in the epicentral area of the Bhuj earthquake (figs. 1, 4). Photo from 

S.F. Obermeier, 1998. 

Figure 6. Collapsed houses 

in the town of Ratnal, in 

the epicentral region of 

the Bhuj earthquake. The 

almost total devastation 

may, in large part, be 

attributed to construction 

methods that have no 

resistance to earthquake 

shaking. 

make assessment of earthquake hazards especially challenging. 

The need to prepare for earthquakes is vividly 

demonstrated by the human tragedy that resulted 

from the Bhuj earthquake. More than 20,000 people perished, in part because many lived in 

homes that had been built with no resistance to 

shaking (fig. 6). Structures in the United States, 

however, are generally better built and should 

better withstand earthquake shaking, even though 

most in the Central and Eastern United States 

were not designed with earthquakes in mind. The 

behavior of earthquakes in Gujarat and New 

Madrid makes preparedness a special challenge—infrequent small and moderate earthquakes give us a false sense of security that we 

are immune from the big earthquakes. 

Reference: 

Obermeier, S.F., 1998, Seismic liquefaction 

features: Examples from paleoseismic 

investigations in the continental United States: 

U.S. Geological Survey Open-File Report 

98-488; available on the Internet as 

http://pubs.usgs.gov/openfile/of98-488/. 

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