National Global Positioning System (GPS) Programme for Earthquake Hazard Assessment- An overview
Status and Achievements
The implementation of the National GPS Programme for Earthquake Hazard Assessment, as recommended by the GPS Expert Group, has been taken up by DST, since 1998. An extensive network of permanent, semi-permanent and field GPS stations is being established by the participating organizations, and a National GPS data centre has been established. Specifications of the GPS instrumentation for this purpose have also been formulated. A Committee has been constituted for overseeing the programme. A brief report on these activities is given below: -
Establishment of Permanent Stations
Permanent GPS stations at Dehradun, Dharmashala, Delhi, Hanle, Leh, Bangalore, Almora, Kodaikanal, Lucknow, Itanagar, Dhanbad, Bhubneswar, Pune and Trivandrum have already been established. Recently, DST has taken an initiative for establishing permanent stations at Tezpur, Gauwahati, Aizawl, Imphal and Kohima in NE India with the help of CMMACS, Bangalore. The establishment of permanent GPS stations in NW part of Himalaya, with the help of Wadia Institute of Himalayan Geology is being taken up and setting up of permanent stations at Jabalpur and Shillong is being done by Survey of India, Dehradun. GPS receivers have also been installed at Tirunelvelli, Kolhapur, Nagpur and Allahabad and data are being collected by Indian Institute of Geomagnetism, Mumbai. DST is also planning to establish permanent stations at Bhopal, Gangtok, Bomdilla, Visakhapatnam, PortBlair and Pondicherry.
National GPS Data Center
Considering the importance of management of a huge volume of GPS data collected from different GPS-related projects, the Expert Group had recommended the establishment of a National GPS data centre at SOI, Dehradun. Subsequently, a National GPS Data Centre has been set up at Survey of India, Dehradun. Achieving of GPS data is being done from the permanent GPS stations of Almora, Lucknow, Kodaikanal, Trivandrum, Pune, Bhubneswar, Leh and Hanle, and data from other stations will be added subsequently. SOI is also planning to make the data available to all authorized users through ftp/internet, so as to reduce response time for data delivery and eliminate avoidable manpower costs.
Transformation Parameters
The reference frame for GPS is World Geodetic System-1984 (WGS-84). GPS measurement at terrestrial sites therefore give coordinates on WGS-84 Datum. This datum is different from that of the Indian Geodetic datum i.e., Everest Datum. All Survey of India Topographical maps are based on this datum. In order to make optimum use of GPS-based coordinate system, it has become essential to determine transformation parameters for conversion of coordination of points from WGS-84 Datum to Everest Datum, and vice versa.
In view of the importance of this task, DST has recently sanctioned a project entitled “Determination of Transformation Parameters between Everest Datum and World Geodetic System-1984 (WGS-84 Datum)” to Survey of India. The Survey of India has already completed GPS measurements at 272 old GT stations for this purpose. The processing of already collected data is in progress. The final values of transformation parameters are expected soon.
Campaign mode studies
All the participating organizations as mentioned above are deeply involved in carrying out the GPS aided crustal deformation studies in different parts of India as per the following: -
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