Monday, May 29, 2023

59% Indian Land Mass Prone To Earthquakes, National Capital In Second Highest Seismic Zone

59% Indian Land Mass Prone To Earthquakes, National Capital In Second Highest Seismic Zone

Cities and towns in eight states and Union Territories of India fall under zone five, putting them at great risk of earthquakes of the highest intensity.

Turkey earthquake
Turkey earthquake Photo: AP/PTI

After a massive 7.8 magnitude earthquake hit southeastern Turkey, near the Syrian border on Monday, rescue and relief operations continue in the affected areas as the death toll keeps rising even three days later. The quake has caused severe damage, claimed over 17,000 lives, and flattened buildings and towns into a mass of debris.

The World Health Organisation has warned that the earthquake in Turkey could affect up to 23 million people and urged other nations to send help to the disaster region. Turkey has declared a state of emergency in 10 provinces.

The Turkey earthquake has opened a series of debates and conversations around seismic ones, quake-prone areas, and how such natural disasters can be predicted earlier to save more lives. Turkey, being in one of the most seismically active zones on the planet was prone to an earthquake of severe intensity, as per experts. However, even though a large quake was expected at some point in this region, no scientist has "ever predicted a major earthquake," the U.S. Geological Survey says. "We do not know how, and we do not expect to know how any time in the foreseeable future. USGS scientists can only calculate the probability that a significant earthquake will occur (shown on our hazard mapping) in a specific area within a certain number of years," a ShortWave podcast episode quoted adding that even the most promising earthquake models only offer seconds of warning.

Seismic Zones: 59Per Cent Of Indian Landmass Prone To Earthquakes

The fatality or intensity of an earthquake is determined by the severity of its shaking or tremors. Areas with un-reinforced buildings or soft soil that prolongs shaking are prone to higher casualties. Quakes or tremors can also cause dangerous secondary effects, like landslides, fires, and tsunamis. The Modified Mercalli Index, developed from Giuseppe Mercalli's Mercalli intensity scale of 1902 is a measure designed to describe the effects of an earthquake, at a given place, on natural features, on industrial installations, and on human beings distinguished from the earthquake's inherent force or strength as measured by seismic magnitude scales. The MMI measures an earthquake’s intensity by considering the severity of the shaking and the amount of damage relative to factors like building construction and soil composition.

In July 2021, minister of state for Science & Technology and Earth Sciences, Jitendra Singh informed the Lok Sabha "that considering the recorded history of earthquakes in the country, a total of 59% of the land mass of India is prone to earthquakes of different intensities". Singh underlined that the total land mass in the country has been classified into four seismic zones, in accordance with the seismic zone map. 

The National Centre for Seismology, under the Ministry of Earth sciences, is responsible for studying earthquake mechanisms and shifts in seismic activities. It has a total of 115 observatories across the country and prepared a government report in 2021, categorizing the country into four seismic zones: zone five (most fatal), zone four, zone three, and zone two (least fatal).

The report undertakes around 11per cent of the country under zone five, including the entirety of entire northeastern India, parts of Jammu and Kashmir, Himachal Pradesh, Uttaranchal, Rann of Kutch in Gujarat, part of North Bihar, and Andaman & Nicobar Islands. 18per cent of Indian land falls in zone four which takes into account the remaining parts of Jammu & Kashmir and Himachal Pradesh, Union Territory of Delhi, Sikkim, northern parts of Uttar Pradesh, Bihar, and West Bengal, parts of Gujarat, and small portions of Maharashtra near the west coast and Rajasthan. Zone three comprises around 30per cent and includes Kerala, Goa, Lakshadweep islands, remaining parts of Uttar Pradesh, Gujarat, and West Bengal, parts of Punjab, Rajasthan, Madhya Pradesh, Bihar, Jharkhand, Chhattisgarh, Maharashtra, Orissa, Andhra Pradesh, Tamil Nadu, and Karnataka. Zone two, the least seismic-prone zone, covers the remaining parts of the country.

Cities and towns in eight states and Union Territories of India fall under zone five, putting them at great risk of earthquakes of the highest intensity. The center's list of cities that lie in the highest seismic zone five include Bhuj in Gujarat, Bihar's Darbhanga, Guwahati in Assam, Kohima in Nagaland, Manipur's Imphal, Mandi in Himachal Pradesh, PortBlair in Andaman and Nicobar, Jammu & Kashmir capital Srinagar and two cities of Assam namely Jorhat and Sadiya.

According to private agency weather forecaster Skymet, Maharashtra's Mumbai also falls in the seismic Zone three. Located on a coastal line, Mumbai is prone to the risk of a tsunami. Chennai, which earlier used to lie in zone two has now shifted to zone three.

The National Capital region comes under zone four, which is the second-highest category. As per an Indian Express report, seismologist and retired professor, Centre for Earth Sciences, Indian Institute of Science, Bangalore, Kusala Rajendran said that while a large earthquake may not originate in Delhi itself, it is prone to the impact of earthquakes originating in the Himalayas.

The Indian Subcontinent And Its History Of Earthquakes

The Indian subcontinent has a history of devastating earthquakes with the major reason for the high frequency and intensity of the earthquakes being that the Indian plate is driving into Asia at a rate of approximately 47 mm/year. Geographical statistics of India show that almost 58per cent of the land is vulnerable to earthquakes. A World Bank and United Nations report shows estimates that around 200 million city dwellers in India will be exposed to storms and earthquakes by 2050. Here is a look at some of the most severe earthquakes in the Indian subcontinent in the past century:

1. On December 26, 2004, a 9.1 magnitude earthquake in Indonesia triggered an Indian Ocean Tsunami, hitting the Andaman Islands. The Tsunami killed around 283,000 people across dozens of countries. It is also the third strongest earthquake since 1950 in human history.

2. Pakistan occupied Kashmir on October 8, 2005, experienced 7.6 magnitude quake, where Some estimate the death toll to be over 87,000.

3. On January 26, 2001, A magnitude 7.7 quake struck Gujarat in India, killing around 20,000 people.
 in the state.

4. April 25, 2015: In Nepal, more than 8,800 people were killed by a magnitude 7.8 earthquake.