The Deccan Volcanic Province in the western part of the peninsular India consists of a thick pile of flood basalts resting mainly on the Archaean and Proterozoic rocks forming the basement. This intraplate region experiences moderate seismic activity, the most recent one being a swarm-type activity in the Palghar region, about 120 km north of Mumbai, that started in November 2018 and has produced a few thousand micro-earthquakes and a 4.3 magnitude earthquake since then. We have carried out a magnetotelluric (MT) study along a 35-km long profile across the seismic zone to delineate the subsurface structure to understand the possible cause for the seismic activity. Broadband MT data were acquired at 18 sites with average station spacing of 2 km. Impedance tensors were analyzed for distortion and dimensionality, decomposed into TE- and TM-mode, and inverted by a 2D inversion algorithm. The geoelectric structure yields an assemblage of highly resistive and moderately conductive blocks in the uppermost crust resting on a major listric-type fault, that possibly reaches the surface at the West Coast Fault from a depth of about 15 km beneath the Panvel flexure zone. In conjunction with the regional Bouguer gravity anomaly and the seismicity distribution, we infer that the upper crustal heterogeneities coupled with the basement fault and low rheological strength of the fractured upper-to-middle crust might be leading to triggering of the seismicity in the region.

印度半岛西部的德干火山省由厚厚的一堆洪水玄武岩组成，主要靠在形成基底的古生界和元古代岩石上。该板内地区经历了中等地震活动，最近的一次是在孟买以北约120公里的帕尔加尔地区的一群虫类活动，该活动于2018年11月开始，自此以来已产生了数千次微地震和4.3级地震。然后。我们在整个地震带沿35公里长的剖面进行了大地电磁（MT）研究，以勾勒出地下结构，以了解地震活动的可能原因。宽带MT数据是在18个站点采集的，平均站点间隔为2 km。分析了阻抗张量的畸变和维数，分解为TE和TM模式，然后通过2D反演算法反演 地电结构在最主要的利斯特型断层的最上地壳中产生了高电阻和中等导电性的块体，这些块体可能从Panvel挠曲带下方约15 km的深度到达西海岸断层的表面。结合区域布格重力异常和地震活动性分布，我们推断上地壳非均质性与基底断层和断裂的上-中地壳的低流变强度相结合可能会触发该地区的地震活动。可能从Panvel挠曲带下方约15 km的深度到达西海岸断层的地表。结合区域布格重力异常和地震活动性分布，我们推断上地壳非均质性加上基底断层和断裂的上-中地壳的低流变强度可能会触发该地区的地震活动。可能从Panvel挠曲带下方约15 km的深度到达西海岸断层的地表。结合区域布格重力异常和地震活动性分布，我们推断上地壳非均质性加上基底断层和断裂的上-中地壳的低流变强度可能会触发该地区的地震活动。