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Joined: 19 Jan 2009 Posts: 2329 Location: RAJKOT,GUJARAT, INDIA
Posted: Wed Nov 22, 2017 5:23 pm Post subject:
RELATION BETWEEN INTENSITY & EARTHQUAKE ZONES OF INDIA
An earthquake is caused by a sudden slip on a fault. Stresses in the earth's outer layer push the sides of the fault together. Stress builds up and the rocks slips suddenly, releasing energy in waves that travel through the earth's crust and cause the shaking. An Earthquake occurs when plates grind and scrape against each other.
India lies at the northwestern end of the IndoAustralian Plate, which encompasses India, Australia, a major portion of the Indian Ocean and other smaller countries. This plate is colliding against the huge Eurasian Plate and going under the Eurasian Plate; this process of one tectonic plate getting under another is responsible for making India a earthquake prone country. A number of significant earthquakes occurred in and around India over the past century. Some of these occurred in populated and urbanized areas and hence caused great damage. Many went unnoticed, as they occurred deep under the Earth’s surface or in relatively un-inhabited places The varying geology at different locations in the country implies that the likelihood of damaging earthquakes taking place at different locations is different. Thus, a seismic zone map is required to identify these regions.
Bureau of Indian Standards, based on the past seismic history, grouped the country into four seismic zones, viz. Zone-II, -III, -IV and –V. Of these, Zone V is the most seismically active region, while zone II is the least. The Modified Mercalli (MM) intensity, which measures the impact of the earthquakes on the surface of the earth, broadly associated with various zones, is as follows:
Seismic Zone Intensity on MM scale:
Seismic Zone
Intensity on MMI scale
% of total area
II (Low intensity zone)
VI (or less)
43%
III (Moderate intensity zone)
VII
27%
IV (Severe intensity zone)
VIII
18%
V (Very severe intensity zone)
IX (and above)
12%
Broadly, Zone-V comprises of entire northeastern India, parts of Jammu and Kashmir, Himachal Pradesh, Uttaranchal, Rann of Kutch in Gujarat, parts of North Bihar and Andaman & Nicobar Islands. Zone-IV covers 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-III comprises of Kerala, Goa, Lakshadweep islands, and remaining parts of Uttar Pradesh, Gujarat and West Bengal, parts of Punjab, Rajasthan, Madhya Pradesh, Bihar, Jharkhand, Chhattisgarh, Maharashtra, Orissa, Andhra Pradesh, Tamilnadu and Karnataka. Zone-II covers remaining parts of the country.
Joined: 19 Jan 2009 Posts: 2329 Location: RAJKOT,GUJARAT, INDIA
Posted: Fri Dec 29, 2017 2:51 am Post subject:
Earthquake In Rudrapayag: Third Tremor To Hit Uttarakhand This Month
The earthquake has been reported to have a depth of 33 km which eliminates the possibility of damage to life and property.
All India | NDTV News Desk | Updated: December 28, 2017 20:12 IST
NEW DELHI: An earthquake measuring 4.7 on the Richter scale shook Uttarakhand's Uttarkashi and Rudraprayag Thursday evening. This is the third earthquake to hit the state this month. No damage to life and property has been reported so far.
Tremors were felt in the state at around 4: 45 pm, according to the Meteorological Department of India. The epicentre of the earthquake is believed to be Chamoli.
The earthquake has been reported to have a depth of 33 km which eliminates the possibility of damage to life and property, MeT Office director Vikram Singh told news agency Press Trust of India. The earthquake has been termed as one of "slight" intensity.
A 5.5 moderate intensity earthquake had hit Rudraprayag on December 6, with tremors were felt across Haryana, Uttar Pradesh, besides Uttarakhand. Another earthquake of 3.3 magnitude had hit the state just a day before that.
Authorities had issued an alert about the possibility of an earthquake.
In November, scientists had predicted the occurrence of a major earthquake in Uttarakhand, where the last major tremor occurred at least 600 years ago. They had also asked the Uttarakhand government to work towards building tremor-resilient infrastructure.
They had said it was imperative for disaster mitigation agencies and the state government to take proactive steps for the amelioration of any impending disaster.
Following this, it was decided that the state would work to the best of its ability to ensure disaster resilience with special emphasis on earthquake resilience.
The hill state, a part of the Himalayan region, falls under a high seismic zone.
Joined: 19 Jan 2009 Posts: 2329 Location: RAJKOT,GUJARAT, INDIA
Posted: Fri Dec 29, 2017 2:57 am Post subject:
4.7 Magnitude Earthquake In Uttarakhand Felt In Rudraprayag, Other Districts
This is the third earthquake in Uttarakhand this month, with two quakes hitting the state in early December. On December 6, an earthquake of magnitude 5.5 struck Uttarakhand, with its epicenter in Rudraprayag.
All India | Edited by Abhimanyu Bose | Updated: December 28, 2017 20:20 IST
NEW DELHI: An earthquake measuring 4.7 on the richter scale hit Uttarakhand today close to 5 pm. The earthquake which originated in the Chamoli district was felt across the state, especially in Rudraprayag.
The 4.7 magnitude earthquake has been reported to have a depth of 33 km which eliminates the possibility of damage to life and property, MeT Office director Vikram Singh told news agency Press Trust of India. The earthquake has been termed as one of "slight" intensity.
According to Vikram Singh, the earthquake struck around 4:45 PM.
This is the third earthquake in Uttarakhand this month, with two quakes hitting the state in early December. On December 6, an earthquake of magnitude 5.5 struck Uttarakhand, with its epicenter in Rudraprayag. The "moderate" intensity earthquake shook the whole state and tremors were felt as far as the Delhi-NCR region.
Only a day before the Rudraprayag earthquake, another earthquake of 3.3 magnitude had struck the state.
In November, scientists participating at a two-day national workshop on disaster resilient infrastructure in the Himalayas said there was a high possibility of a devastating earthquake in Uttarakhand.
Noting that Utttarakhand was in the Central Seismic Gap where a high probability exists of a major earthquake, they said it was imperative for disaster mitigation agencies and the state government to take proactive steps for the amelioration of any impending disaster.
The last major earthquake struck Uttarakhand at least 600 years ago.
Scientists in the workshop also spoke about the extra care that needs to be taken for the design of structures in hill slopes and the implications of wrong design or construction practices. They also stressed on the requirement of specific construction guidelines for hilly regions.
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