Journal of Earth System Science | 2021
A study of Palnadu earthquake sequence in the Cuddapah basin and its tectonic implications
Abstract
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.