Studies in the Koyna, India, 2004–2024
摘要
Chapter 7 deals with the work having been carried out in the Koyna region during the period 2004 to 2024. This includes successful forecast of M ~ 4 earthquakes in Koyna region, and initiation of an ICDP supported detailed scientific work in the Koyna region to learn more about the genesis of artificial water reservoir triggered earthquakes. The first ICDP meeting was held at NGRI, Hyderabad and Koyna. The suitability of the Koyna region for near field study of earthquakes was well appreciated and accepted. Certain additional work to be carried out was suggested. This included airborne gravity, gravity-gradient and magnetic surveys; LiDAR coverage of the entire Koyna-seismic zone; setting up of the borehole seismic stations for a better location of earthquakes; magnetotelluric and a variety of other investigations. All this work was completed in the next two years and the second ICDP workshop was held with national and international participation in 2013. Satisfied with the work having been completed in the past two years, a go ahead was given to set up a Pilot Borehole of about 3 km depth in a suitable location. After studying the earthquake occurring patterns and other logistics consideration, a bore hole site close to the Donachiwada Fault that hosted the 1967 M 6.3 and several M ~ 5 earthquakes was chosen. The Pilot Borehole was spudded in December 2016 and completed in June 2016. The three km deep borehole provided excellent cores and an opportunity of conducting several important investigations. The results of the drilling of the Pilot Borehole and related measurements as well as other work carried out since 2013 was presented in the 2017 ICDP workshop. The workshop also provided guidelines for the future course of action. The work was going on in full swing after the third ICDP workshop when the Covid-19 pandemic put brakes on the progress and broke the momentum. The 3 years of uncertainty (2019-2022) has resulted in certain setbacks in meeting the planned targets. Some of the planned targets and the timelines were worked out keeping in view the conditions prevailing in the country and in the world. I am hopeful, that a dream of drilling a 7 km deep borehole right into the heart of the seismic zone to catch a Live earthquake may become a reality someday.