Felt Effects of the M~w~7.6 Bhuj Earthquake, India

Martin, S.\* and Hough, S.E.\*\*

\*Nowrosjee Wadia College, Pune 411001

\*\* United States Geological Survey, Pasadena 91106

ABSTRACT:

Tremors from the M~w~7.6 Bhuj earthquake reverberated throughout the
Indian Sub-continent. It was the largest earthquake in 50 years in
independent India, and was the first major earthquake since 1950 to be
felt over such a wide area in South Asia. After the shock, reports of
the earthquake being felt and of damage from various parts of the
sub-continent started filtering in. News of the widespread destruction
and casualties also began coming in via television stations and Internet
based news agencies. Many people also sent in their observations via the
Internet.

Light to moderate shaking was experienced more than 1500 kilometres
away. The maximum intensity was 10 on the Modified Mercalli Scale in the
vicinity of the epicentre. 2 reports that seemed to indicate MM 12 were
also received.

All this, along with information collected from several local and
regional websites, has been catalogued. At present, there are 310
reports available from various parts of India, as also from neighbouring
Pakistan, Nepal and Bangladesh. This information is available online at
[**http://pasadena.wr.usgs.gov/office/hough/bhujmain.htm**](http://pasadena.wr.usgs.gov/office/hough/bhujmain.htm)

Method of Data Collection and Assessment:

Shaking from the main shock was experienced over a very wide area of the
Indian Sub-continent. It was felt as far away as Kabul, Afghanistan in
the north and Shillong (Meghalaya), India in the northeast. It was also
felt in parts of eastern and southern India.

We have collected and complied reports of the damage and felt
experiences, from print, television and web based news agencies. In what
might be called a first for a major earthquake in India, many people
also went online and began to surf the Internet for information on the
tremors they had just felt. Many people visited the "Did You Feel It? "
WebPages on the USGS and ASC websites and sent in their observations at
the following URL's,

USGS:
[**http://neic.usgs.gov/neis/felt/report.html**](http://neic.usgs.gov/neis/felt/report.html)

ASC:
[**http://www.asc-india.org/felt.htm**](http://www.asc-india.org/felt.htm)

We found another valuable source of information of on the website of the
British Broadcasting Corporation (BBC), at BBC Talking Point. At the
Amateur Seismic Centre, there is a network of volunteers in various
parts of India and Pakistan. This network known as the ASC Volunteer
Network, was set up with the very idea of collecting data after large
and widely felt earthquakes. When the Bhuj earthquake hit, many of these
volunteers who either themselves felt it or were later informed of it,
got to work collecting and sending reports to the main bureau of the ASC
in Pune. We have also gone though dozens of articles that appeared in
newspapers, both national and regional like The Times of India, The
Indian Express, Sandhyanand, etc. following the earthquake. News from
Internet based agencies, such as "123india.com" and "indiaexpress.com"
was used. Damage reports were also included from Kutch websites such as
"Kutchinfo.com", "Panjokutch.com" and "Vagad.com". Information from the
city of Ahmedabad, was obtained from a website called "www.e-setu.com",
which had an interactive map of the city that displayed the locations
and in some cases the names of collapsed buildings.

We have used the Modified Mercalli Intensity (MMI; Wood and Neuman,
1931) scale to assign intensity values to these locations. Though the
Maurik-Ssan-Karnik (MSK) scale is currently used in India by the
Geological Survey of India (GSI) while carrying out intensity studies of
earthquakes, we feel justified to use the MMI scale as it will enable us
to easily make comparisons with similar sized historic earthquakes,
where limited information on the type and quality of construction are
available. We would also like to point out that at present there is a
wealth of intensity data for the 1897, 1905 and 1934 earthquakes
(Oldham, 1899; Middlemiss, 1910; Dunn *et al* 1939), which have been
each classified using different intensity scales other than the MMI and
MSK scales. Though this data is not adequate to assign MSK values, it is
more than enough to use the MMI scale. Thus we will be able to correctly
estimate the magnitudes of historic earthquakes, for which instrumental
data is unavailable.

In order to map out the shaking we employed a simple mathematical
approach whereby the data is contoured using a continuous curvature
girding algorithm. A uniform grid of estimated intensity values are
determined by soling the equation,

(1-T) \* L\[L(z)\] + T \* L(z) = 0

where T is a tension factor between 0 to 1, and L indicates the
Laplacian operator (Wessel and Smith, 1991). A smoothing value of 0
obtains the minimum curvature solution, which can produce minima and
maxima away from constrained values. With a value of 1, no minima or
maxima occur away from the control points. Low MMI values are introduced
around the periphery of the map so that the low intensity field decays
at the edges. We then plot the results following the convention used to
generate conventional "ShakeMaps". Conventional ShakeMaps (Wald, *et al*
1999) are instrumental data to estimate shaking severity; here we
generate intensity maps directly from MMI values (Figures 1 and 2).

It must be noted that in very few instances, single reports of the event
being "not felt" were received from areas that were well within the
isoseismal V. As this would considerably affect the overall distribution
of shaking intensities, we have assigned appropriate values for these
locations. There were two such locations. The first, a report from the
town of Dalauda (ASC Volunteer Network) stated that a person who was
outdoors at the time did not feel the quake. Most other areas around
this location experienced the quake quite strongly (MM V -- VI) and
hence we assume a value of IV - V for this location. Similarly at
Kakrapar in southwestern Gujarat, we knew from newspaper reports (Indian
Express, January 28^th^, 2001) that the nuclear reactor at Kakrapar had
not tripped. The frequency of shaking here reached 51.2 Hz, which was
very close to 51.5 Hz, which was the "tripping frequency". The reactors
were designed such that they would chemically end the fission reaction
immediately when the level of shaking reached 0.1g thus reducing the
danger of a nuclear accident. Hence we assigned an intensity of VI
(Bolt, 2000) to this location. The other "not felt" reports were
received from southern most parts of the country and were on the
furthest edge of the isoseismal III.

The information sources for individual reports are available at the
following link and will not be repeated in the course of this paper.

([**http://pasadena.wr.usgs.gov/office/hough/bhuj/bhujmain.htm**](http://pasadena.wr.usgs.gov/office/hough/bhuj/bhujmain.htm))

Observed Shaking Patterns:

Past major earthquakes in India (M\>7) have been felt widely. This
recent earthquake is the second such event to occur in the Kutchh area.
The previous upheaval was in 1819 (Bilham, 1999) and though a little
smaller in size, was felt over a similar expanse of the sub-continent.
The 1819, 1905 and 1934 earthquakes, with the exception of the 1897
event, produced damage (MM\>VII) within 150 kilometres of the epicentre.
Damage patterns from the 2001 earthquake indicate considerable highs in
the intensity especially in the Cambay Basin, on Salsette Island
(Mumbai), in Rajasthan and most interestingly in far off places such as
Kathmandu, Nepal and the Kaveri Delta in southern India.

We found that the strongest shaking, MM VIII - X, was experienced in
Kutchh and Saurashtra in Gujarat as well as in parts of Sindh, Pakistan.
Serious ground cracking and near total destruction of structures was
observed in and around Anjar, Bhachau and Gandhidham. Intense
liquefaction occurred in Kutchh, most notably in the Rann of Kutchh
northeast of Bhuj. In Bhuj itself, shaking was particularly strong,
powerful enough to knock people to the ground and make it impossible for
them to move. Liquefaction and earthquake fountains were also reported
in Saurashtra, from Jamnagar district on the southern coast of the Gulf
of Kutchh. The furthest reports of liquefaction were from Wataman and
other places, on the banks of the Sabarmati River, 50 kilometres West
South West of Nadiad. A report of ground cracking was also sent in from
Morbi (ASC Volunteer Network). In Pakistan, craters were formed and
water was emitted from the earth in large quantities near Badin and
Khadan.

Outside the Kutchh district in the rest of Gujarat, damage corresponded
to MM intensity VI-VII. But we found that in some situations the
intensities reached MM VIII. In the Cambay Basin, liquefaction was
reported from many places along the Sabarmati River in Gujarat. In
Ahmedabad, dozens of buildings collapsed, mainly along the Sabarmati and
in areas built over its ancient bed. The water table also rose by 2.5
centimetres at Sola in Ahmedabad. In neighbouring Surat, a single
high-rise building was the only major casualty of the quake in the city.
Wall collapses were reported from other sections of the city. Most
cities in this sediment filled were badly affected experiencing MM VII
or higher. In Ahmedabad and Surat the highest intensities were VIII.

Beyond Gujarat, we observed damage rapidly dropping off towards the
south and the southeast. Along the Konkan coast of Maharashtra, moderate
intensities of V -- VI were experienced, e.g. Silvassa. However, some
places like Billimoria, Mumbai, Navsari and Vashi saw intensities as
high as VI - VII. Several buildings are known to have collapsed in
Billimoria and Navsari. In Mumbai and Vashi many buildings developed
cracks, the worst instance being in Wadala (Mumbai), where a fire
brigade station was considerably damaged. Buildings also developed
cracks at Antop Hill, Mazegaon, Mumbai Central and Vikhroli. As the
quake hit in the morning, many people recalled how the shaking spilt
cups of freshly prepared tea. In other instances (ASC Felt Reports) at
Andheri, a Mumbai suburb, water spilt from a fish tank and at
Prabhadevi, showpieces were knocked off shelves. The earthquake was also
felt outdoors in Mumbai. In the city of Nashik, there were a few wall
collapses in the Budhwar Peth area. However, in most other places in
Maharashtra, like Pune and Kolhapur, we found that though the shock was
felt for more than 30 seconds no damage was caused. In Pune the tremors
were not felt outdoors. In Madhya Pradesh too, MMI V or lower was
experienced in most parts including Bhopal, Indore and Ujjain. An MMI of
VI was assigned to a place called Maheshwari, where a fort developed
cracks.

But north of the epicentre, we found damage to be much greater when
compared to areas at similar distances, to the south and southeast. The
isoseismal VI encompassed a much wider area in these parts as compared
to the south and the southeast. The state of Rajasthan in this region,
saw much more damage than did the states of Madhya Pradesh and
Maharashtra. Many buildings were severely damaged in southern parts and
some, in places like Bakhasar, a few even collapsed. Many historic forts
and palaces in places like Jaisalmer and Jodhpur were damaged.

MMI V -- VI was experienced in southern and central Pakistan, including
at Karachi. In Hyderabad (Sindh, Pakistan), a multi storey building that
was under construction collapsed, on neighbouring houses resulting in a
few fatalities. Only light tremors were reported from all other parts of
the sub-continent. In some areas of India and Pakistan, like Bangalore,
Lahore, Lucknow, Kanpur, Kolkata and New Delhi, we found news articles
that said that along with light tremors, overhead lamps and fans were
seen shaking. In other parts like Chandigarh and Unchahar, people felt
giddy but didn't associate the sensation with an earthquake, until they
heard of it on television. At Hyderabad (Andhra Pradesh, India) light
tremors were felt only by people in high-rise buildings in the Begumpet
area of the city. Along the Coromandel Coast, tremors were felt from
Bhubaneshwar to Chennai.

We came across some very interesting observations from a few places at
very great distances from the epicentre. In Kathmandu, Nepal, MMI IV was
experienced. Furniture was shaken and suspended objects were seen
oscillating. It was felt strongly enough for people to recognize it as
an earthquake and run outdoors. Shaking reported as an "aftershock" also
came in from Satkhira, on the Indo-Bangladesh border, between the cities
of Kolkata (India) and Khulna (Bangladesh). Residents of this area
apparently took to the streets in fear of a stronger jolt. This area
lies on the Ganga delta. MM intensities of III -- IV were also felt in
Kolkata. Even more bizarre were the MM intensities of IV -- V, which we
found to have occurred in the Kaveri delta in the southern state of
Tamil Nadu and the Union Territory of Pondicherry. People outdoors at a
Republic Day gathering in Pondicherry, felt giddy. Many recognized it as
an earthquake and rushed towards the exits in panic. In Kumbakonam,
students performing on a makeshift stage panicked and jumped off, as the
stage began to shake and in Thiruvaiyaru, heavy sacks of grains were
reportedly displaced.

Though this earthquake was reportedly felt in Kerala, we have not been
able to track down any reports that might throw light on the intensity
of the shock in any one area, in this fairly densely populated coastal
belt. The earthquake was not felt in Salem, Tamil Nadu.

Though it was felt extensively to the east, to the west it was not felt
in Iran, Oman or in the south, in Sri Lanka.

So for we have come across two cases indicative of extremely violent
shaking (Asian Age, January 30th, 2001), one from Bhuj and the other
from the neighbouring town of Sukhpur. In the first instance, in Bhuj, a
school teacher, said he saw waves on the surface of the earth during the
earthquake, which he compared to waves he'd seen in the sea at Mumbai.
At Sukhpur, a 7-year-old schoolgirl was knocked off her feet and thrown
a short distance away by the shaking. This motion also injured her
parents, who were in their fields at the time of the earthquake. The
girl said that a crack opened up and her friends who were with her fell
into it \[Her actual description said that the earth had "swallowed"
them up\].

There was another intriguing incident which we came across on a message
board at the BBC website, BBC Talking Point. It is the only such report
we have come across from anywhere, and the furthest location from the
epicentral region where this is known to have occurred. It has been
reproduced herewith in entirety,

> "We have seen since yesterday nearly 100 buildings have collapsed
> totally, the worst of it was one school building opposite Cadila
> factory, Ghodasar, Ahmedabad. Where nearly 50 children are been
> trapped under the debris. One of our colleagues Mr. Chirayu Pandya
> residing in Bopal (*Bhopal*) has witnessed with his naked eyes, the
> moment (*movement*) of waves passing through his bungalow in open
> agriculture land, seeing moments (*movements*) of trees and earth
> rising up and coming back to its position as waves moved faster."
>
> Kamlesh Shah, India (BBC Talking Point)

So far this is the only report of this nature that we are aware of.
Bhopal (MM V) lies more than 700 kilometres from the epicentre.
Presently we know of a similar phenomenon of "ground waves" being
observed at Allahabad (Uttar Pradesh), during the 1897 Assam earthquake.

Conclusions:

We noted that all the areas that saw higher than expected values lie
along the coasts, along estuaries, river valleys and deltas. The maximum
intensity of X was seen in Kutchh at locations near the epicentre. The
possibility of MM XII is still a mystery as there are only two reports
of shaking that can be classified as being that strong and no strong
motions records are available to us from the area. Despite this, damage
in Bhuj was not comparable with MM XII but rather with MM IX. The case
is the same for the town of Sukhpur, where MM IX was seen. Hence we have
assigned MMI's of IX to both these locations.

In general the observed pattern of shaking was comparable to other past
earthquakes, in particular with the 1819 earthquake. It was felt much
more widely to the east than to the west, as we can see from the fact
that it was felt in Chittagong (Bangladesh) but not in Muscat (Oman).

Acknowledgements:

We wish to thank all those who contributed their observations and made
this report possible. We are also grateful to members of the ASC
Volunteer Network, in particular, Naeem Beguwala (ASC Mumbai), Anand
Joshi (ASC Ahmedabad), Bharat Tarachandani (ASC Vadodara), Sachin
Bhatnagar (ASC Chandigarh), M.R. Singh (ASC Nalasopara), M.K. Devarajan
(ASC Nagpur), Pratik Sabherwal (ASC Noida) and Ravi Govande (ASC Thane)
for their reports. We also wish to thank Ms. A. Coutinho for providing
us with felt reports from Silvassa and Vashi. And we also greatly
appreciate the reports sent in by many individuals from various parts of
India and Pakistan, via the "Did You Feel It? Web page on the ASC and
USGS websites.

References:

ABAG -
[[http://www.abag.ca.gov/bayarea/eqmaps/doc/mmi_plain.html]{.underline}](http://www.abag.ca.gov/bayarea/eqmaps/doc/mmi_plain.html)

Bilham, R., "Slip parameters for the Rann of Kachchh, India, 16 June
1819 earthquake quantified from contemporary accounts, in Stewart, I. S.
& Vita-Finzi, C. (Eds)", Coastal Tectonics. Geological Society London,
1999, vol. 146, pp. 295-318.

Bolt, B.A., "Earthquakes", 2000, W.H. Freeman and Company, New York,
U.S.A.

Dunn, J.A., Auden, J.B.,Ghosh, A.M.N, and Roy, S.C., "The Bihar-Nepal
earthquake of 1934", Memoirs of the Geological Survey of India, 1939,
Calcutta, vol. 73, pp 391.

Middlemiss, C.S., "The Kangra Earthquake of 4^th^ April 1905" Memoirs of
the Geological Survey of India, 1910, vol. 38, pp 409

Oldham, R.D., "Report on the Great Earthquake of June 12^th^, 1897",
Memoirs of the Geological Survey of India, 1899, vol. 29, pp 379

Wald, D.J., Quitoriano, V., Heaton, T.H., Kanamori, H., Serivner, C.W.,
and Worden, C.B., "Trinet 'Shakemaps': Rapid generation of instrumental
ground motion and intensity maps for earthquakes in Southern
California", Earthquake Spectra, 1999, 15, pp. 537 -- 556.

Wessel, P., and Smith, W.H.F., "Free software helps map and display
data", EOS Trans., AGU, 1991, 72, 441, 445.

Wood, H. O., and Neumann, F., "Modified Mercalli Intensity Scale of
1931" BSSA, 1931, Vol. 21, pp. 277-283.

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  ![](media/image1.jpeg){width="5.947222222222222in"
  height="7.878472222222222in"}

  **Figure 1** -- Distribution of Modified Mercalli Intensities in India
  and the neighbouring areas for the Mw 7.6 Bhuj earthquake.
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  ![](media/image2.jpeg){width="5.996527777777778in"
  height="7.529861111111111in"}

  **Figure 2** -- Distribution of Modified Mercalli Intensities in
  Gujarat and the neighbouring areas for the Mw 7.6 Bhuj earthquake.
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