Koyna region in western India experienced more than 1,00,000 earthquakes of different magnitudes (M ~ 1.0–6.3) in the past five decades. Earthquakes in this region are believed to be triggered by a change in fluid pressure due to the percolation of the reservoir (Koyna and Warna reservoir) water into the subsurface. A drilling program was set up by the Ministry of Earth Sciences, India and International Continental Scientific Drilling Program (ICDP) to study the deep subsurface lithology, structure, thermal attributes, etc. as the area is covered by ~ 950 m of thick Deccan basalts. This paper reviews all the hypotheses proposed by earlier workers to explain the mechanism of reservoir trigger causing earthquakes and summarizes such theories to a simple generic model. Slip tendency analysis was further carried out based on the proposed model to explain the dependence of fault slip on fault geometry, rock mechanical properties, stress and fluid gradients. Finally, faults at various depths were characterized (favourably oriented, unfavourably oriented and severely misoriented) based on their potential to go into failure.

中文翻译：

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Koyna地震：储层触发的地震活动性机理和地下断层滑动趋势分析

印度西部的科伊纳地区经历了1,00,000多次不同程度的地震（M 过去的十年间（〜1.0–6.3）。人们认为，该区域的地震是由于储层（科伊纳和瓦尔纳水库）水渗入地下而引起的流体压力变化引起的。印度地球科学部和国际大陆科学钻探计划（ICDP）制定了钻探计划，以研究深层地下岩性，结构，热属性等，因为该地区被约950 m厚的Deccan玄武岩覆盖。本文回顾了早期工作人员提出的所有假设，以解释水库触发引起地震的机制，并将这些理论总结为一个简单的通用模型。在提出的模型的基础上进一步进行了滑动趋势分析，以解释断层滑动对断层几何形状，岩石力学特性，应力和流体梯度。最后，根据断层的潜在破坏力，对深层断层进行了特征化（有利取向，不利取向和严重错位）。