23rd Annual Convention and Seminar on Exploration Geophysics

Special Theme: Engineering and Environmental Studies

Jointly Organized by
Geological Survey of India
North Eastern Council
Oil & Natural Gas Corpn. Limited
Oil India Limited
Indian Society of Engineering Geology
Association of Exploration Geophysicists

The geology of the North East India endowed with rich mineral and hydrocarbon deposits is not documented sufficiently. There is a need to highlight the geological and technical framework of this region to initiate research in understanding the complicated geology of this thrusted region, through modern exploration tools.

Focusing on the geological problems that are characteristic to North East India, the special theme for this seminar was Engineering and Environmental Studies. This seminar was of immense value to professional geoscientists, industrial planners, investors, engineering Geologists and research scholars of geosciences. Attendees at the seminar shared a comprehensive review of the geological, geophysical and engineering challenges.

About 60 papers were presented during the 2 day technical (Oral and Poster) sessions. The Following papers were adjudged as the best papers and the MBR Rao Gold medal was awarded to the best paper

Best Paper : Awarded the MBR Rao Gold Medal

· A Re-look into gravity field of northeast Indiaby J.V. Rama Rao and R.M.C. Prasad

Second best paper

· Processing and Interpretation of Ground Magnetic Data Acquired along Silchar-Imphal-Loresh corridor (Eastern Cachar and Manipur Area) by D. Rai and V. Ramaswamy

Third best paper

· Mixing Geometries in 3D Seismic Data Acquisition - A Case Study by R. Dasgupta, A. Das, A. Kumar, T. Bhattacharya, D.S. Manral and B.M. Sinha

Best poster presentation

· Petroleum Potential of Tanzania Deep Sea Basin by A.D. Makishe and O.S. Mtunguja

Workshop on The Great Shillong Earthquake - 1897 : A Centennial Retrospective

Sponsored by
North Eastern Council
Department of Science & Technology

Association of Exploration Geophysicists (AEG) organized a workshop on the Great Shillong Earthquake - 1897 : A Centennial Retrospective with the support of Department of Science and Technology (DST) and the North Eastern Council (NEC) at Shillong on 18 November, 1997. This workshop was organized in Shillong to spread awareness and draw the attention people living in the North East Region to the Great Shillong Earthquake of 1897, June 12.
Slide shows and a poster exhibition depicting the after effects of the quake was open to the public. The aim was to create a platform from where people could be educated about earthquakes so that the degree of earthquake preparedness of the region can be increased.

During the workshop a book entitled Great Shillong Earthquake - 1897 : A Centennial Retrospective was released, which contains five review articles and abstracts of 115 papers published on this topic during the last 100 years. The book is of immense value to practicing Geoscientists, Engineers and Planners. Two volumes containing the five review articles and full papers of all the abstracts published in the proceedings is available for reference from AEG.

Results obtained from the Workshop

The results obtained from the workshop are:

· Large parts of India are susceptible to major earthquakes particularly, the NE Region, which is one of the six most quake prone regions in the world.

· Damages due to the earthquakes are not necessarily correlated with the magnitude or intensity or other seismological characters alone.

· The damages are more often dependent on the time and location of occurrence, nature of the substratum in the affected areas, Population density, Construction and land use practices.

· The duration and amplitude of ground motion due to earth tremors increases by an order of magnitude from hard-rock area to river sediments.

· The liquefaction processes in soft, fine sediments can start even with earthquakes of magnitude of 6 or more causing collapse of buildings and structures and landslides along high slopes.

The seismic phenomena, so frequent in this part of the country, cannot be prevented and at this stage of development of science cannot be predicted. However, precautions can be taken to mitigate the hazards caused by implementing a centralized information system linked to a highly decentralized, yet quick to respond, execution methodology.

Recommendations for Earthquake Disaster Mitigation Strategies

The earth scientists at the workshop recommended two sets of steps for earthquake disaster mitigation strategies.

· Short term steps aimed primarily at seismic hazard mitigation

· Long term measures aimed at better understanding and modeling the seismicity in this region through coordinated research efforts with outputs fed on to the operational hazards mitigation efforts.

Short Term Steps for Implementing a Seismic Hazard Mitigation System

· Systematic identification of land areas susceptible to liquefaction during earth tremors applying strong motion and other seismic records Quaternary Geology and Geomorphic mapping techniques on the highest priority, utilizing the existing mapping coverage by Geological Survey of India etc. and expeditious coverage of the unmapped terrain. Inputs from research/experimental efforts using diverse other techniques may be used, where available, for further refining such information base.

· Systematic Landslide Hazard potential Zonation Mapping exercises along all the hill areas of the country.

· Impress upon the Bureau of Indian Standards to expeditiously complete the ongoing exercise at Detailed seismic Zonation of the country and give priority in this to North East India.

· Legally Recognize nodal provision for a seismic design of buildings, bridges and other major constructions including buildings with 3 or more floors and enforce their observation through mandatory clearance of design drawings by authorized boards comprising earth science and engineering experts.

· Micro-level seismic hazard zonation of major habitation centres, starting with the fast growing capital cities of the seven NE States and Gauhati in particular.

· Carry out a seismic qualification survey of existing major buildings in the NER and encourage retrofitting, where necessary to prolong their life in this quake-prone region.

· Strengthen community buildings such as schools, hospitals, places of worship etc. which could serve as possible shelters in the event of a catastrophic earthquake.

· Introduce awareness courses on seismic potential of the area in the school curriculum including adult education activities in all the NE states and channelizing the Door Darshan and AIR network maximally in Headquarters.

· Seismotectonic Studies may be systematically pursued to identify discrete seismogenic units for effective hazards evaluation and mitigation.

· Initiate large scale training of artisans and building supervisors at local level in the NE Region in construction of a Seismically designed buildings.

· Implement a well-designed Disaster Management System involving civil governmental agencies, army and para-military organizations, local bodies, voluntary agencies and educational institutions. The system may be designed to accept updates from the outputs of the efforts suggested above and institutional mechanisms identified.

Long term Steps of Research on Seismicity

· To set up a multi-disciplinary research institute in the NE Region exclusively for focused studies on problems related to seismicity such as data collection in diverse fields, earthquake precursor studies on gravity, magnetic, electrical, seismic and chemical properties of rocks and geological structures, animal behavior etc. The above related studies can be further supplemented or panned out by studies to be carried out with the relevant national institutions, with which the presently planned institution shall work in close collaboration.

· Establish a well-designed network of seismograph stations for continuous monitoring with broad-band, strong motion arrays, telemetrically connected with a central station is the NE Region for immediate analysis and delivery of information for hazard mitigation.

· Explore the possibility of setting up warning system linking seismic network with power distribution networks, railways etc. so as to enable quick action for decommissioning them.

· Universities in the Region may be encouraged to start teaching-cum research departments devoted to various earthquakes related fields.

The Assembly authorized the Secretary, AEG to communicate the above resolution to the concerned agencies.

Glimples of the Great Shillong Earthquake - 1897

A slide show was displaying the photographs of the Great Shillong Earthquake was open to the public during the seminar.The rare 100 year old Black and White photographs which was published in the "Memoirs of Geological Survey of India" by R.D. Oldham were scanned and digitally enhanced/restored.A few of the B&W photographs were artificially coloured to enhance their visual appeal. The following are snapshots of few of the slides that were on display. The show generated a lot of interest among the general public.