Seismology Division

Introduction

Seismicity programme is a research driven programme with a long prospective to provide a fillip to the science of seismology. The aim of the programme is to provide added thrust to the earthquake- related studies and also to generate inputs in the form of knowledge based products to help earthquake Disaster mitigation effort through S&T intervention.

The Key objectives of the programme are as follows:-

• To promote R&D in the field of earthquake studies.
  
• To create scientific infrastructure in the form of seismographs, strong motion accelerographs, Global Positioning Systems (GPS) and other collateral geophysical systems for generating high quality data sets to facilitate advanced research.
  
• To generate knowledge-based products such as microzonation maps to help in earthquake disaster mitigation and management.
  
• To create awareness about earthquakes amongst masses.
  
• To create specialized manpower and capabilities to deal with specific scientific problems in different facets of seismology and earthquake engineering.

The Seismicity Programme has been evolved with a view to understand the earthquake processes/mechanism related to the Indian Lithosphere, their recurrence interval and their manifestation on the surface towards developing knowledge and techniques for hazard mitigation. During the last few years, a good infrastructure has been created at various identified locations and lab facilities have been established at different institutions. Many groups from North-East India were developed under the programme after suitable training at lead institutions. These groups, in North-East India, have gained experience and developed expertise in different aspects of seismology and related studies. With the increased interest of the scientific community in the programme, new geographical areas like Delhi region, Peninsular shield, Bihar plains and Andaman & Nicober Island region were also taken up for carrying out integrated studies. Special initiatives were launched for Northeast region and Modern seismological observations have been set up at selected locations. Seismic Observational Network

Obtaining precise location of epicenters is vital to earthquake studies. During the last decade, earthquake detection capabilities have been significantly improved due to expansion and upgradation of seismological network in the country. It is now possible to record the events down to Magnitude 3.5 due to better detection capabilities. India Meteorological Department (IMD) is the nodal agency as far as seismic observational network is concerned. At present 51 Seismological Observatories are being maintained by IMD under the National Network. Department of Science & Technology (DST) has supported a number of projects for setting up of Seismological Observatories for seismological research in project mode.

In addition, DST has also supported for establishment of digital telemetric clusters in Kumaun, Koyna and Khandwa region. Strong motion arrays have also been installed in Bhuj, Delhi and other selected locations.

Seismic Observatories

Fig-1: Seismic Observatories in NW Himalaya

Fig-2: Seismic Observatories in NE Himalaya

45 Broad Band seismic Observatories are in operation in Project mode for Carrying out research in seismology in North Western and North Eastern Himalayan region (Figure 1 & 2). Ten broad band stations have also been established in the Peninsular Shield after the 1993 Kilari earthquake (Figure-3). These stations have helped in obtaining improved picture of local and regional seismicity in this region as well as other important problems.

Fig-3: Seismic Observatories in Peninsular shield

Telemetric Clusters

Koyana, Maharastra

Teleseismic network at Koyana is being maintained and operated by NGRI. This network includes one central station at Gokul and five stations around it.

Fig- 4:Khandwa Telemetric Network.

Khandwa, M.P An 11 element Seismic cluster, established at Khandwa region is being maintained operated by Geological Survey of India.

The digital telemetered Network in the Kumaon Himalaya is being maintained by Kumaon University generates high quality data for the crucial central segment of the Himalaya. Strong Motion Network

Himalayan Strong Motion Network. Network of Strong motion accelerographs have been strengthened in Himalayan region in the form of seismic arrays. Upgradation of analog accelerograph with state-of-the-art digital instruments & further expansion in Indo-Gangetic plains are being planned by DST through a project entitled "National Strong Motion Instrumentation Network" under the Mission Mode Project . This project envisages to expand the existing networks in the seismic zone IV and V and cover some important cities in zone III.

Fig-5:Strongmotion Network in Himalaya

Fig-6:Delhi Strong motion Network

Delhi Strong motion Network The 16 element Delhi Strong Motion Accelerograph network supported by DST has been operational since 1996 . Out of the sixteen stations located in Delhi, 8 are set up in Delhi while remaining eight are in the close vicinity of Delhi. The network is being upgraded by adding 12 more SM instruments. The data generated through this strong motion network will provide basic inputs for the Microzonation study of Delhi.

Strong motion Network in Other region

Other organizations like Indian Institute of Technology, Kharagpur, National Geophysical Research Institute, Hyderabad also maintaining different strong motion network in and around Sikkim and Bhuj region.

National Seismological Data Center

The National Seismological Data Centre (NSDC) at the IMD headquarters, New Delhi have been established to cater the needs of near real time access of wave form data from field stations. Twelve of the upgraded observatories of Global Seismograph Network (GSN) standards are linked through V-Sat to the Central recording Station to enable real time data transmission. Other seismic observatories are being planned to be connected through- V-SAT communication by IMD. Laboratory and Testing Facility

Some of the major facilities supported by DST are as follows:

The Acoustic Emission Laboratory has been set up at NGRI to study the behavior of rocks in dry & water saturated condition.	Fig-7: Acoustic Emission Laboratory at NGRI.
Completely automated servo- controlled cyclic toxiania testing facility with submersible load cell with cell capacity of 10 tons have been created at Indian Institute of Sciences, Bangalore. This facility is capable of performing static and dynamic triaxial compression and extension tests with stress or strain controlled tests.	Fig-8: Triaxial Testing facility at IISC, Bangalore
The Shake Table Facility of IIT, Roorkee has been upgraded to simulate the accelrogram of a given earthquake.	Fig-9: Shake Table Facility at IIT, Roorkee
A radio carbon lab has been set up at NGRI, Hyderabnad to help in palaeoseismological studies, ground water dating and palaeoclimatic and palaeo oceanographic studies. A thermoluminiscenes laboratory has been established at Manipur University to strengthen palaeoseismological studies.

A National Programme on Global Positioning System (GPS) was launched by DST during 1997-98 for monitoring the crustal deformations due to earthquake occurrence and other geodynamic phenomena. As of now, 30 permanent GPS Stations all over the country have been established (Figure-10), and initiative is being taken to establish more permanent stations. A number of organizations are also deeply involved in studying the crustal deformation process in campaign mode (Figure-11). Some significant results related to the movement of Indian Plate and velocity vectors have been obtained. GPS derived velocity and deformation rates in the Himalayan arc vary from west to east suggesting the deformation mechanisms in Ladakh, Garhwal , Kumaun and Sikkim Himalayas are different and are to be treated differently. GPS derived extension vector between the Himalayan sites and Lhasa is consistent with the east west extension of southern Tibet. Kachchh GPS results give post seismic deformation consistent with Bhuj rupture zone as GPS measurements were made after the 2001 earthquake. GPS measurements in the northeast India seem to indicate that there is strong lateral variation in the convergence rates in northeast Himalayas.

Fig-10: Network of Permanent GPS stations under the National GPS Programme

Fig-11: Different GPS campaigns under the National GPS Programme

The Mission mode project is an attempt to provide value added products for earthquake disaster mitigation through technological interventions with the technical support of several Institutions. The project is distinct and specific in terms of its scope, content, time frame, participation and deliverables with respect to various ongoing schemes. Under this Programme, following activities have been supported:-

• Upgradation of the National Strong Motion Instrumentation Network -three hundred digital SM instrument are planned to be deployed in Zone V&IV.
  
• Setting up of multi-parametric geophysical observatories -this is aimed at initiating a systematic programme of earthquake precursory studies.
  
• School earthquake monitoring laboratory programme - it is planned to deploy low version seismographs in 100 selected schools in NW & NE region.
  
• Specialized training programme in computational seismology - this will help in developing the capability in data analysis in seismology.
  
• Production of instructional and self-learning material - it is planned to develop the information in the form of monographs audio-video and brochures, which will help in educating local people and creating awareness among masses.
  
• Seismo-tectonic model of the Uttaranchal Himalaya - the project is aimed at developing a crustal model of Uttaranchal Himalaya.
  
• Library of Empirical Green's Function for NCR region of Delhi. - this will help in building up of damage scenario due to a possible large earthquake in the vicinity of Delhi.

The present Knoweldge does not allow prediction of earthquakes in terms of the location , time and magnitude of an earthquake, it is better to prepare against earthquake disaster. Preparation of earthquake Hazard Map is an important aspect which needs to be addressed. Seismic Microzonation study is the first step towards seismic hazard assessment. Seismic Microzonation is the process of estimating the likely seismic hazard on the surface of the earth due to a future scenario earthquake.

Jabalpur Microzonation A pilot project was initiated by DST Microzonation map of Jabalpur involving GSI, NGRI, CBRI, IMD and Jabalpur Engineering College as active participants. The Microzonation map of Jabalpur has been prepared. The Jabaopur urban area has been classified into 3 units of low, medium and high hazard, the last category being restricted to the alluvial fell, sediment cover etc. The experience of Jabalpur Microzonation studies is expected to provide guidelines for similar studies being undertaken in Guwahati, Sikkim and Delhi.

Fig-12: Risk Map of Jabalpur

Fig-13: Microzonation map of Sikkim

Sikkim Microzonation Seismic hazard assessment of Sikkim Himalaya was carried out with the help of site response studies, factor analysis and computing response characteristics. Seismic Microzonation map of Sikkim has been prepared by IIT, Kharagpur integrating various data like site factor, geology, soil types, slope, peak, Ground Acceleration and resonant frequency. Initiatives have already been taken for carrying out seismic Microzonation studies of cities like Delhi, Ahmedabad, Bangalore & Guwahati.

The Jai Vigyan Technology Mission Project- Natural Hazard Mitigation in Himalaya was launched in the year 2000-2001. The following progress have been made under the programme.

• Setting up of Seismological observatories in the North Eastern region sanctioned to NGRI.
  Under the project, five seismic observatories have been installed and commissioned at Rupa, Jogighopa, Nangalbibra, Khonsa, Yaongyimsen of North Eastern region of India.
  Using the high quality broadband data acquired by the seismic stations in the region an attempt was made for determining the crustal structure beneath the seismic stations located in different geological units like Shillong plateau, Mikiri Hills, Assam valley and in the foothills of Himalaya in Northeast by using the state-of-the-art techniques like the receiver functions.
• Initiation of activities at Geophysical Research laboratory, Allahabad sanctioned to IIG, Mumbai.
  A multicomponent programme to monitor geomagnetic, geoelectrical and Very Low Frequency (VLF) electromagnetic emissions to isolate and understand the nature of precursory signals of earthquakes in the Himalaya has been initiated. The State-of-the-art facilities are being deployed at the centre to provide calibration and reference measurements. In order to monitor precursory signals from the Himalaya, two field stations at Cham and Bhatwari have been set up in Garhwal Himalaya. Proton precession magnetometers, three Component Fluxgate Magnetometers (CFM) and Ball Antenna systems are installed at base stations to monitor stress induced changes in magnetization, resistivity and seismo-electromagnetic emissions in VLF bands.
• Geotechnical investigations for landslide control measures in the North Easern (NE) region.
  Six new projects were sanctioned to the local institutions of NE region for geotechnical investigations of landslides during the financial year 2001-2002. Out of the above projects, one project has been completed under which a microzonation map of landslide affected area, between Banderdeva-Gohpur in Itanagar, Arunachal Pradesh has been prepared. Other projects are progressing well.

Indigenous Development of Geoscientific Equipment

During the recent years, a major emphasis has been towards indigenous design and development of seismic instrumentation. The Central Scientific Instruments Organisation (CSIO), Chandigarh, Earthquake Engineering Department at IITR-Roorkee, Indian Institute of Science, Bangalore and National Physical Laboratory, New Delhi are involved in this task.

The electronic remote rescue system developed by NPL uses radio waves to detect presence of any animate subjects.

IIT-R, Roorkee has developed a Structural Response Recorder (SSR) to study the structural response of civil structures.

Earthquake Risk Evaluation Centre (EREC)

The Government of India has set up an Earthquake Risk Evaluation Centre (EREC) at IMD to provide an impetus and focused attention towards mitigating earthquake disaster. Its main objective is to execute and promote specific tasks for mapping of earthquake hazard, vulnerability and risk.

India has suffered due to a number of big earthquakes in the last one and half decades. To understand the natural process and minimize the damage due to earthquakes it is essential to aware the community about the earthquakes.

• DST has started a Observatory Programme for the schools of Himalayan region in Earthquakes (HIMSCOPE) under the Mission Mode Project. The aim of the project is to equip 100 representative schools in the Himalayan belt with low cost earthquake monitoring systems to create newer capabilities in capturing and analyzing earthquake related information.
• In order to create awareness amongst masses, it is planned to prepare self-learning/instructional and mass awareness material on earthquake preparedness through monographs, posters, power point presentation and audiovisuals. The material will be prepared, initially in English and Hindi and subsequently translated in to other languages.
• In addition to the above earthquake awareness programme have been initiated in Rajasthan and Delhi.

Publications

DST has supported a number of publications related to seismological research in India. Some of the publications are mentioned below:

• Uttarkashi Earthquake, published by Geological Society of India, 1995
• Earthquake Research in India, published by Seismology Division, Department of Science & Technology, New Delhi, 1999.
• Geodynamics of the NW Himalaya, Memoir No.6 published by Gondwana Research Group, 1999.
• Application of GIS in earthquakes and landslides hazard assessment, published by Seismology Division, Department of Science & Technology, New Delhi, 2003.
• Earthquake studies in India since 1993, published by Geological Society of India, 2003
• Latur earthquake published by Geological Society of India, Bangalore, 2003.
• Indigenous Development of seismic Instrumentation for earthquake Monitoring, Risk assessment and Mitigation published by Seismology Division, Department of Science & Technology, New Delhi, 2003
• Strong Motion Studies in India, published by Seismology Division, Department of Science & Technology, New Delhi, 2003
• Geo-scientific studies in and around Delhi published by Seismology Division, Department of Science & Technology, New Delhi,2004
• A National GPS programme for earthquake hazard assessment, published by Seismology Division, Department of Science & Technology, New Delhi, 2005.
• Seismology Update, biannual publication of Seismology Division, Department of Science & Technology, New Delhi

Understanding earthquake processes

• Nucleation process of earthquakes, leading to better assessment of preparation zones.
• Style of deformation and mechanism of earthquakes.
• Spatial and temporal pattern of earthquakes and their relation to tectonic features.

Basic research

• Wave propagation in complex media.
• Modelling source time functions and earth structure
• Mapping mantle discontinuities
• Develop attenuation relationships; studies on anisotropy

Structure and tectonics

• Mapping the deep structure of peninsular India, Himalaya and the trans-Himalaya using BB seismology
• Modelling of travel time data to obtain a reference velocity model.
• Quantification of deformation using space geodesy (GPS); mapping of post-deformation fields (In SAR).

Outreach programmes

• Earthquake education-reaching the public through school students.
• Awareness through distribution of educational material, audiovisual media and contact programmes.

Earthquake hazard mitigation

• Understanding the seismic sources in the country.
• Mapping active faults and assessing recurrence patterns.
• Quantification of probabilistic seismic hazard (site and region-specific).
• Preparation of strong motion and PGA maps.
• Understanding the attenuation of seismic waves in various regions.
• Microzonation of mega cities.
• Generation of GIS-based data products for effective hazard management.
  

Please download the Acrobate Reader to open .pdf file.

Contact

For more information on Seismicity please contact :

Dr V Rao Aiyagari
Adviser & Head (Seismicity)
Department of Science & Technology
Technology Bhawan
New Mehrauli Road
New Delhi-110 016.
Tele: 011-26963695
Email: venktesh at nic dot in