SEISMOLOGICAL INVESTIGATION

General

Seismological investigations were carried out by operating seismological observatories located at and around major Irrigation Projects by the Seismology Unit under Engineering Geology Division of Gujarat Engineering Research Institute, Vadodara. The Seismology unit came into existence in the year 1982. Subsequently Government of Gujarat has established 16 Seismological observatories. Seismograms received from these observatories are scanned for record of earthquakes. These are analysed at GERI to determine the various parameters of earthquakes such as arrival time, magnitude, epicenter, epicentral distance, energy released etc. ; epicentral location maps are prepared and correlation with existing known tectonic features is being done.

Tectonic Map of Gujarat

Work carried out

Ø The seismicity of the project area is being assessed and reports are prepared and submitted to Government for reviewing seismic status of various projects. This is also useful for planning of future projects in the state. Apart from the seismicity studies of various irrigation projects, GERI took up the Seismological studies of Gujarat state as a whole.

Ø Monitored of Microearthquake activity in Dharampur - Vansda talukas of Valsad district in South Gujarat by establishing a temporary network of Portable Seismographs in an area of about 20 km x 20 km during 1986-1990 . Analysis and reporting of more than 25,000 earthquakes (-0.6 ≤ ML ≤ 4.6) was carried out.

Ø Precursor research studies viz Radioactive , Geochemical analysis, Geomagnetic field variation, Geodetic monitoring, Geological, Hot spring water temperature variation etc were also taken up during above activity in collaboration with various national organizations viz. National Geophysical Research Institute (NGRI), Hyderabad; Bhabha Atomic Research Centre (BARC), Mumbai; Geological Survey of India (GSI), Jaipur; Survey of India (SOI), Dehradun; Indian Institute of Geomagnetism (IIG), Mumbai; India Meteorological Department (IMD), New Delhi etc

In addition, major earthquake events are also recorded from various parts of India and World, which are analyzed and reported to Government of Gujarat and various national institutions such as IMD, New Delhi; Department of Science & Technology (DST) , New Delhi etc. Special seismological investigations were carried out with Micro Earthquake Recorders for monitoring micro earthquake activities in the state. Intensity surveys are carried out in region around epicenter immediately after a felt shock ..

Following the Bhuj earthquake of January 26, 2001, a need has been felt to enhance the seismological studies being carried out in Gujarat.

Aftermath - Devastating Bhuj Earthquake Jan 26 '2001	Seismogram Of Bhuj Earthquake Jan 26 ' 2001 recorded at Dharoi observatory in North Gujarat

In view of this, a network of 22 Broad Band Seismological observatories and 40 Strong Motion Accelerographs with state of art technology was established by Seismology Unit of this Institute in Gujarat under Asian Development Bank (ADB) assisted Gujarat State Disaster Management Authority (GSDMA) , Gandhinagar’s project to study precisely seismicity of state as a whole. Under the project VSAT communication system is deployed for on-line data transmission from 22 observatories to Central Seismic Data Centre at Gandhinagar. The data in digital format is anlaysed, interpreted, archived and studied for research work. Planning is made to on-line disseminate these data to National Seismic Data Centre, IMD, New Delhi also.

Additionally established a mobile network of six DELTA GEON Seismographs in Geoblock under stress in coordination with Delta Institute, Moscow, Russian . At present the network is established in and around Bhuj-Rapar region

Important Studies Undertaken

Monitored and studied Micro-earthquake activities in South Gujarat by establishing a temporary network of portable Micro earthquake Recorders.

Monitored and studied Micro earthquake activities in North Gujarat by establishing a temporary seismological observatory at Sipu / Dharoi irrigation project.

Established and monitoring a Broad Band Seismological observatory at Dharoi project (north Gujarat) under World Bank aided DST, New Delhi’s project on ‘Establishment of a network of 10 new Broad Band Seismological observatories in Peninsular shield region of India’ since the year 2000.

Established a network of 22 Broad Band Seismological Observatories & 40 Strong Motion Accelerograph stations in Gujarat to study the seismicity of the state under ADB funded GSDMA, Gandhinagar’s project during 2007

Established and monitoring a mobile network of 6 Delta Geon Seismographs in a Geo-block under stress (around Bhuj-Rapar)

Future Studies

Establishment and monitoring a network of Seismological Observatories around proposed Kalpasar project

Kalpasar, a multipurpose water resources project has been proposed by constructing a dam across Gulf of Khambhat connecting Saurashtra Peninsular with Gujarat main land. The proposed Kalpasar reservoir would store surplus fresh water from the rivers of Cambay and Narmada basins viz mainly Narmada, Mahi, Sabarmati and Dhadhar. The reconnaissance and pre-feasibility, studies were conducted and are encouraging. Now, while carrying out feasibility studies, the seismic status of the project area prior to the construction of the dam is one of the important factors. This is required for proper design of the seismic structure of the dam by taking into account certain earthquake design parameters. Accordingly a proposal, amounting Rs 7.0 crore, on the project ‘Establishment and monitoring a network of Seismological Observatories around proposed multipurpose Kalpasar project’ was submitted to government and the same has been accepted by Kalpasar Prabhag, Govt. of Gujarat, in principle. The project will be comprising of establishment of 8 Broad Band Seismological observatories and monitoring and study the seismicity around the project for 5 years. All the 8 observatories are planned to be connected with VSAT communication system for online data trnsmission to Central Data Centre at GERI, Vadodara

Published Research Papers/Articles

1. ‘Earthquake swarm activity in South Gujarat’,1991, Mausam, IMD, New Delhi

2. ‘Earthquakes’,1992, Navnirman, Irrigation Dept, Govt. of Gujarat

3. ‘Seismic Status and Dam Safety in North Gujarat, India’,1996, Proceedings

,2^nd International Conference on Dam Safety Evaluation , Trivandrum

4. ‘Earthquake - Instrumentation’,1996, Navnirman, Irrigation Dept, Govt. of

Gujarat

5. ‘Present Status of Seismicity of Gujarat’, 1997,Vayumandal,IMD,New Delhi

6. ‘Geophysical Investigations – An Introduction’,1998, Navnirman, Irrigation

Dept, Govt. of Gujarat.

7. ‘Seismological Investigations around River Valley Projects’, 1998, Navnirman, Irrigation Dept, Govt. of Gujarat.
8. ‘Statistical Parameters of Bhuj Earthquake Sequence of January 26, 2001’, 2001, International Conference on Seismic Hazard with special reference to Bhuj earthquake of January , 2001.( Proceedings of Indian Acad. of Sciences, Earth Planet Sci., 112, No. 3,September 2003,1-4’)

9. ‘Earthquake Magnitude Scales’,2003, Navnirman, Irrigation Dept, Govt. of Gujarat

10. ‘Networking for earthquake monitoring in Gujarat’ , Indian Geotechnical

Conference –IGC-2005,2005, Nirma University, Ahmedabad

11. ‘Seismicity Monitoring of Kachchh region with a close network of Delta Geon

Seismographs’,2006,13^th symposium on Earthquake Engineering , IIT,

Roorkee

12. ‘Broad Band Seismic network for Gujarat’, 2006,13^th symposium on

Earthquake Engineering , IIT, Roorkee

13. ‘Strange attractor in earthquake swarms near Valsad (Gujarat), India’, 2007,

Mausam, IMD, New Delhi

14. ‘The Gujarat (India) Seismic Network’ ;2008, Seismological Research Letters;

Vol: 79, Number 6