• G SURESH

Articles written in Journal of Earth System Science

• Magnitude estimation of regional earthquakes in India and its adjoining region

To provide reliable and quick estimation of magnitude for moderate to large earthquakes at regional distances, two magnitude relations specific to the peninsular shield have been proposed based on long-period magnitude ($M_{A}$) and energy magnitude ($M_{E}$), using broadband velocity data of 23 regional events recorded at 18-station seismic network in the state of Telangana and Andhra Pradesh, India. $M_{A}$ is estimated using amplitude of filtered (0.03–0.08 Hz) broadband velocity seismograms, while $M_{E}$ is estimated based on radiated energy using broadband velocity spectra. It is observed that $M_{A}$ for larger events with $M_{w}$ >7.2 saturates, whilst $M_{E}$ does not suffer from saturation even for larger events. Thus, it is apparent that these two magnitude relations can provide magnitude estimates without saturation for all moderate to large regional earthquakes, which, in turn, can provide a homogeneous catalogue for moderate to large regional Indian earthquakes. The data transmission from remote stations to the central server at CSIR-National Geophysical Research Institute (NGRI) is quasi-real-time since it is connected by GPRS and VSAT. Using the proposed region specific magnitude relationships it becomes possible to estimate reliable magnitudes for moderate to large regional Indian earthquakes ($M_{w} \leq 7.2$) within 30 min of the occurrence of an event.

• A study of Palnadu earthquake sequence in the Cuddapah basin and its tectonic implications

On January 26, 2020, a moderate-sized earthquake ($M_{L}$ ${\sim}$ 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.

$\bf{Highlights}$

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

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

$\bullet$ The focal mechanism solution of the main-shock ($M_{L}$ 4.6) shows a strike-slip motion with a reverse component.

• # Journal of Earth System Science

Volume 132, 2023
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019