Seismology

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Earthquake Information

Seismological Observatories
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Seismic Zoning Map

Seismicity Map

List of some significant Earthquakes in India and its neighbourhood

Significant Earthquakes

Seismological activities

1.   Earthquake monitoring

India Meteorological Department (IMD) is the nodal agency of Government of India responsible for monitoring seismic activity in and around the country. IMD has rendered more than hundred ten years of seismological service to the nation with the first seismological observatory of the country having been set up by the department at Kolkata in 1898. The operational task of the department is to quickly estimate the earthquake source parameters immediately on occurrence of an earthquake and disseminate the information to all the user agencies including the concerned State and Central Government agencies responsible for carrying out relief and rehabilitation measures. The information relating to under-sea earthquakes capable of generating tsunamis on the Indian coastal regions is also disseminated to all concerned user agencies including the Indian National Centre for Ocean Information Services (INCOIS), Hyderabad for issue of tsunami related messages and warnings. The earthquake information is also transmitted to public information channels, press, media etc. and posted on IMD’s Website.

2. Earthquake Operational Centre

An Earthquake Operational Centre is functioning on a 24X7 basis at IMD Headquarters in New Delhi, which has the operational responsibility of keeping a round-the-clock watch of seismic activity in and around the country. The responsibilities of the Centre include retrieval of waveform data from remote field stations either in real time or through VSAT / dial up communication facilities, data analyses and quick dissemination of earthquake information to various user agencies including State and Central Government departments dealing with relief and rehabilitation measures. The information relating to under-sea earthquakes capable of generating tsunamis on the Indian coastal regions is also disseminated to all concerned user agencies including the Indian National Centre for Ocean Information Services (INCOIS), Hyderabad for issue of tsunami related bulletins and warnings. The earthquake information is also transmitted to public information channels, press, media etc. and posted on IMD’s Website. The Duty officer may be contacted at the following numbers for earthquake related information:

011-24619943 / 24624588

The information on recent significant earthquakes can also be obtained from an Interactive Voice Recording System (IVRS) through the following number:

011-24657879

3.   National Seismological Network (NSN)

India Meteorological Department is maintaining a country wide National Seismological Network (NSN) consisting of 55 observatories, which includes four observatories in Himachal Pradesh for dam related studies under the Bhakra Management Board (BMB). Of these, 30 stations are equipped with state-of-art broadband sensors, high dynamic range (24-bit) digitizers, GPS time synchronization and facility to access the data remotely through satellite communications and telephone mode. The remaining 25 stations are equipped with analog seismograph systems, which are proposed to be replaced by digital seismograph systems. The locations of these 55 observatories are shown in the map. India Meteorological Department is also maintaining a 16-station V-SAT based digital seismic telemetry system around National Capital Territory (NCT) of Delhi for close monitoring of seismic activity in the region. As part of the Indian Tsunami Early Warning Center, India Meteorological Department has established a 17-station Real Time Seismic Monitoring Network (RTSMN), which includes 13 existing stations of IMD and 4 new stations located at Campbell Bay, Diglipur, Hyderabad and Dharmshala.

4.   Real Time Seismic Monitoring Network (RTSMN)

In the aftermath of the Great Sumatra earthquake of 26^th December, 2004, Ministry of Earth Sciences has set up an Indian Tsunami Early Warning Center at the Indian National Centre for Ocean Information Services (INCOIS), Hyderabad. The Center is mandated to provide advance warnings on Tsunamis likely to affect the coastal areas of the country. As part of this, a 17-station Real Time Seismic Monitoring Network (RTSMN) has been set up by India Meteorological Department. The network is capable of monitoring and reporting, in least possible time, the occurrence of earthquakes capable of generating Tsunamis likely to affect the Indian coastal regions. The data from the 17 Broadband seismic field stations is transmitted simultaneously in real time through V-SAT communication facilities to the Central Receiving Stations (CRSs) located at IMD, New Delhi and INCOIS, Hyderabad for processing and interpretation. The CRSs are equipped with state-of-art computing hardware, communication, data processing, visualization and dissemination facilities. The earthquake information is disseminated through various communication channels to all the concerned user agencies in a fully automated mode. Based on the earthquake information provided by the Real Time Seismic Monitoring Network and other ocean related observations / analyses, INCOIS evaluates the tsunamigenic potential of the undersea earthquakes and issue necessary warnings / alerts as per the situation.

5.   National Seismological Bulletin



Seismology Division publishes a monthly National Seismological Bulletin, containing the phase data and the processed information on source parameters of all earthquakes located by the Seismological Network of IMD. India is a permanent Member of the International Seismological Centre (ISC), UK. Seismological Bulletins containing processed information on earthquakes recorded by the seismological observatories of IMD are regularly supplied to International Seismological Centre (ISC), UK for incorporation in the ISC’s Monthly Seismological Bulletins, which contain information on earthquakes occurring all across the globe compiled using the data collected from global stations.

6.   National Seismological Data Base Centre (NSDC)

The seismological data from all the network stations is compiled, processed, analyzed and archived systematically at the National Seismological Database Centre (NSDC) at IMD Headquarters, Lodi Road, New Delhi on a regular basis. Seismology Division supplies earthquake data / seismicity reports of specific regions to insurance companies, industrial units, power houses, river valley projects etc. on payment basis. Consultancy services are also provided to various state and central government agencies on earthquake related matters. Seismological data and earthquake related information is also supplied to various user agencies dealing with relief and rehabilitation measures, earthquake disaster mitigation and management related matters, seismic zoning, etc. Earthquake data is also supplied, on request, to various scientific, academic and R&D institutions for research purposes.

7.   International Collaboration in Seismology

As part of international collaboration, bilateral cooperation in the fields of Seismology and earthquake prediction research are currently being pursued with Russia, Iceland and Mexico. The Indo-Russian Centre for Earthquake Research (IRCER), established in 2003 in IMD premises, as part of Integrated Long Term Programme (ILTP) of Department of Science and Technology, has the primary mandate of development and coordination of collaborative projects in the field of earthquake research through multi-institutional participation. IRCER is coordinating several projects being implemented by various R&D and academic institutions in the country including IMD and a platform for a coordinated mechanism for synthesis of the investigations / results, is being provided by the Centre.

8.   Seismology Training

Seismology Division organizes periodical training programs/refresher courses in Seismology and allied subjects at various levels to station operators and various departmental officers and non-departmental agencies, such as Indian Navy, Air Force, State government agencies, etc.

9.   Seismology Workshop

            Development and manufacture of analog type seismological equipment, accessories and spares is undertaken in the departmental workshop. Besides catering to the needs of the observatories under the national network, the department also makes a limited supply of analog seismological equipment to other institutions.

10. Seismic Zoning of India

            Bureau of Indian Standards [IS-1893 – part – 1: 2002], based on various scientific inputs from a number of agencies including earthquake data supplied by IMD, has grouped the country into four seismic zones viz., Zone-II, -III, -IV and -V. Of these, zone V is rated as 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

            II (Low intensity zone)                                VI (or less)

            III (Moderate intensity zone)                       VII

            IV (Severe intensity zone)                          VIII

            V (Very severe intensity zone)                 IX (and above)

11. Research and Development

IMD scientists are also actively involved in Research and Developmental related activities in the field of Seismology and allied subjects. The upgraded seismological network has generated very useful and unique digital broadband and strong motion data sets for several significant earthquakes including the recent great Sumatra earthquake of 26^th December, 2004 and Pakistan earthquake of 8^th October 2005. Analyses of these data sets have greatly helped in improving our understanding about the earthquake processes in the inter- and intra-plate seismic regimes and the crust and upper mantle structure of the Peninsular shield region.

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