Q.34. Write a case study of Earthquake in
“Bhuj-Gujrat”. Explain “Land-slidde”. (AKTU. - 2015 - 16)
Ans. 2001 Gujarat earthquake: -
The 2001 Gujarat earthquake,
also known as the Bhuj earthquake, occurred on 26 January, India's 52nd
Republic Day, at 08:46 AM IST and lasted for over 2 minutes. The epicentre was
about 9 km south-southwest of the village of Chobari in Bhachau Taluka of Kutch
District of Gujarat, India.
The intraplate earthquake reached
7.7 on the moment magnitude scale and had a maximum felt intensity of X
(Extreme) on the Mercalli intensity scale. The earthquake killed between 13,805
and 20,023 people (including 18 in southeastern Pakistan), injured another
167,000 and destroyed nearly 400,000 homes.
Gujarat lies 300–400 km from the
plate boundary between the Indian Plate and the Eurasian Plate, but the current
tectonics are still governed by the effects of the continuing continental
collision along this boundary. During the break-up of Gondwana in the Jurassic,
this area was affected by rifting with a roughly west-east trend. During the
collision with Eurasia the area has undergone shortening, involving both
reactivation of the original rift faults and development of new low-angle
thrust faults. The related folding has formed a series of ranges, particularly
in central Kutch.
The focal mechanism of most
earthquakes is consistent with reverse faulting on reactivated rift faults. The
pattern of uplift and subsidence associated with the 1819 Rann of Kutch
earthquake is consistent with reactivation of such a fault.
The 2001 Gujarat earthquake was
caused by movement on a previously unknown south-dipping fault, trending
parallel to the inferred rift structures.
Effects: -
The death toll in the Kutch region was 12,300. Bhuj, which was situated
only 20 km away from the epicenter, was devastated. Considerable damage also
occurred in Bhachau and Anjar with hundreds of villages flattened in Taluka of
Anjar, Bhuj and Bhachau. Over a million structures were damaged or destroyed, including
many historic buildings and tourist attractions. The quake destroyed around 40%
of homes, eight schools, two hospitals and 4 km of road in Bhuj, and partly
destroyed the city's historic Swaminarayan temple and historic fort as well
Prag Mahal and Aina Mahal.
In Ahmedabad, Gujarat's commercial
capital with a population of 5.6 million, as many as 50 multi-story buildings
collapsed and several hundred people were killed. Total property damage was
estimated at $5.5 billion and rising. In Kutch, the earthquake destroyed about
60% of food and water supplies and around 258,000 houses–90% of the district's
housing stock. The biggest setback was the total demolition of the Bhuj Civil
hospital. The Indian military provided emergency support which was later augmented
by the International Federation of Red Cross and Red Crescent Society. A
temporary Red Cross hospital remained in Bhuj to provide care while a
replacement hospital was built.
Land-slide: -
A landslide, also known as a
landslip, is a form of mass wasting that includes a wide range of ground
movements, such as rockfalls, deep failure of slopes, and shallow debris flows.
Landslides can occur in underwater, called a submarine landslide, coastal and
onshore environments. Although the action of gravity is the primary driving
force for a landslide to occur, there are other contributing factors affecting
the original slope stability. Typically, pre-conditional factors build up
specific sub-surface conditions that make the area/slope prone to failure, whereas
the actual landslide often requires a trigger before being released. Landslides
should not be confused with mud flows, a form of mass wasting involving very to
extremely rapid flow of debris that has become partially or fully liquefied by
the addition of significant amounts of water to the source material.
