The Koyna-Warna region in western India is well known around the globe for recurrent reservoir-triggered seismicity soon after the impoundment of the Koyna and Warna reservoirs. The seismicity pattern delineates two distinct seismic zones, Koyna Seismic Zone (KSZ) and Warna Seismic Zone (WSZ). To understand the seismic potential of the region, we estimated the strain budget by analysing the published GPS velocities and earthquake catalogue of the region. Although the KSZ and WSZ are separated by ~25 km only, the rate of strain accumulation in the former (2.55E+16 Nm/year) is estimated to be ~11 times larger when compared to the latter (2.29E+15 Nm/year). However, KSZ releases only ~20% of the accumulated energy per year, whereas, WSZ releases most of the accumulated energy in the form of earthquakes. Best fitting elastic dislocation model for KSZ also shows a left lateral slip of 0.8 mm/year and the fault plane dips at ~77° in NW direction. The distribution of strain accumulation and release rates in the two regions may be attributed to significant spatial variability in the medium properties such as density, elastic constants and fracture density. This proposition is supported by other geophysical studies in the region. A density model constructed from Airborne Gravity Gradiometry (AGG) data also shows relatively higher average density for KSZ compared to the WSZ. The strain budget of the region suggests that the earthquake activity in KSZ may continue for a longer time whereas it may diminish in the WSZ in the near future. Based on the gross strain estimates, the KSZ has accumulated enough strain post the 1967 M6.3 Koyna earthquake to generate an event of M_w5.8, provided the accumulated strain is released in a single event. The seismic hazard scenario in terms of peak ground acceleration (PGA) due to a potential M_w5.8 event is estimated using the stochastic simulation (SS) technique. The simulated PGA at a radial distance of ~40km from the source zone is estimated to range between 0.09 and 0.26g with an expected intensity of V–VII.

在 Koyna 和 Warna 水库蓄水后不久，印度西部的 Koyna-Warna 地区因水库引发的周期性地震活动而闻名于世。地震活动模式描绘了两个不同的地震带，科伊纳地震带 (KSZ) 和瓦尔纳地震带 (WSZ)。为了了解该地区的地震潜力，我们通过分析该地区已发布的 GPS 速度和地震目录来估计应变预算。尽管 KSZ 和 WSZ 仅相隔约 25 公里，但与后者 (2.29E+15 Nm/年) 相比，前者的应变积累率 (2.55E+16 Nm/年) 估计要大约 11 倍年）。然而，KSZ 每年仅释放约 20% 的累积能量，而 WSZ 以地震的形式释放大部分累积能量。KSZ 的最佳拟合弹性位错模型还显示了 0.8 毫米/年的左侧侧滑，断层平面在 NW 方向倾斜约 77°。这两个区域中应变积累和释放速率的分布可能归因于介质特性的显着空间变异性，例如密度、弹性常数和裂缝密度。该提议得到了该地区其他地球物理研究的支持。根据机载重力梯度测量 (AGG) 数据构建的密度模型也显示，与 WSZ 相比，KSZ 的平均密度相对较高。该地区的应变收支表明，KSZ 的地震活动可能会持续更长的时间，而在不久的将来，WSZ 的地震活动可能会减弱。根据总应变估计，KSZ 在 1967 M6 之后积累了足够的应变。_w 5.8，前提是累积应变在单个事件中释放。使用随机模拟 (SS) 技术估计由于潜在 M _w 5.8 事件引起的峰值地面加速度 (PGA) 方面的地震危险情景。距源区约 40 公里径向距离处的模拟 PGA 估计范围在 0.09 到 0.26g 之间，预期强度为 V-VII。