Abstract

On January 26, 2020, a moderate-sized earthquake (M_L ~ 4.6) located in the Palnadu sub-basin of Cuddapah basin was felt both in the states of Telangana and Andhra Pradesh. The earthquakes prior and after the M_L 4.6 are located close to the thrust and along the periphery of the backwaters of the Pulichintala Reservoir. About 965 earthquakes in the magnitude range of 0.1–4.6 M_L have been located by seismological network. The epicentral parameters obtained from double difference technique illuminated a steep seismogenic structure extending up to 8 km depth using a minimum 1-D velocity model. The b-value estimate is 0.82 for a completeness magnitude of M_c 1.8 and could be associated with the intraplate event having a longer recurrence time. The focal mechanism solution obtained from waveform inversion reveals a pure double-couple mechanism of a strike-slip motion with a reverse component on a N–S trending focal plane. The spatial distribution of the earthquake sequence and fault plane solution of the main event are close to a thrust which is the most likely source region of the main-shock.

Highlights

• Relocation of the Palnadu earthquake sequence illuminated a steep seismogenic structure extending up to 8 km depth.

• The estimated lower b-value (0.82) could be associated with the intraplate event having a longer recurrence time.

• The focal mechanism solution of the main-shock (M_L 4.6) shows a strike-slip motion with a reverse component.

中文翻译：

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Cuddapah盆地Palnadu地震序列研究及其构造意义。

摘要

2020年1月26日，一个中等规模的地震（中号_大号位于Cuddapah盆地Palnadu子流域〜4.6）有人认为无论是在特兰伽纳和安得拉邦的状态。M _L 4.6之前和之后的地震都位于推力附近，并沿Pulichintala水库回水的边缘。通过地震网络定位了大约965次0.1-4.6 M _L范围内的地震。从双差技术获得的震中参数使用最小一维速度模型照亮了一个延伸至8 km深度的陡峭地震构造。的b -值估计是0.82的完整性大小中号_Ç1.8，可能与板内事件的复发时间较长有关。从波形反演获得的震源机制解揭示了走滑运动的纯双耦合机制，在N–S趋势焦面上具有反向分量。地震序列的空间分布和主要事件的断层平面解接近于推力，而后者是最有可能是主震的震源区域。

强调

• 帕尔纳杜地震序列的搬迁照亮了一个陡峭的地震构造，延伸到8 km的深度。

• 估计的较低b值（0.82）可能与具有较长复发时间的板内事件相关。

• 主震（震源机制解决方案中号_大号4.6）示出了具有反向分量的走滑运动。