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CE 6999-Special Topic Seminar - Status of Seismic Hazard Estimation in India

CE 6999-Special Topic Seminar - Status of Seismic Hazard Estimation in India

Date15th Jun 2021

Time03:00 PM

Venue Google Meet Link : https://meet.google.com/tyx-czkg-sdd

PAST EVENT

Details

Earthquake engineering analysis aims to ensure that a structure can withstand a given level of ground shaking while maintaining a desired level of performance. However, there is a great deal of uncertainty about the location, size, and resulting shaking intensity of future earthquakes. The present review is focused on investigating the status of seismic hazard estimation and the design practices followed in India. The first seismic zoning map of India was proposed in 1956, where the country is divided into severe, moderate, and minor hazard zones. In 1962, the first national-level hazard map is introduced in IS 1893 for practicing engineers in India. With suitable modifications in course of time, the code introduced seismic zone factors in 1975, on a more rational basis. This division of the country into five zones starting from earthquake-free to severe earthquake-prone areas based on the expected intensity values is proved wrong by the 1993 Khillari earthquake that occurred in the earthquake-free zone. Presently, the code specifies that every region in the country is seismic. However, the appropriateness of using an empirically fixed zone factor for larger regions, without considering the geological and tectonic characteristics is still questionable. Hence, with an increasing need for a proper understanding of hazard estimation, many studies have come up with different hazard analysis procedures and zoning maps for India. Probabilistic Seismic Hazard Analysis (PSHA) is one of the methods, where an explicit description of the distribution of future shaking that may occur at a site by combining all the possible uncertainties are incorporated. With the advances in knowledge, geological and tectonic information, and availability of a more comprehensive database of earthquakes, one might expect current seismic hazard maps to look very different from the first probabilistic seismic hazard maps produced decades ago. Hence, it is interesting to examine the extent to which the advances have influenced seismic zoning in India. Apart from response spectra, many parameters that characterize the amplitude, frequency, or duration can be derived from ground motion. However, there is no mention of such studies conducted for India to link with the seismic hazard. In this study, a review of the seismic hazard assessment in India is performed to understand the status of hazard estimations and how far we have come from the traditional seismic design approaches.

Speakers

Ms. K P Sreejaya, CE17D401

Department of Civil Engineering