Appraisal of Veldurti–Kalva–Gani (VKG) fault, Cuddapah Basin, India: Gravity and magnetic approach

A ~60 km long Veldurti–Kalva–Gani (VKG) fault is one of the identified strike-slip faults extending from Eastern Dharwar Craton (EDC) to Cuddapah basin in South Indian Shield. The recorded recent seismic activity during year 2012–2016 show occurrences of three microseismic events (< M w 2.0) in t...

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Bibliographic Details
Published in:Journal of Earth System Science 2021-12, Vol.130 (1), p.40, Article 40
Main Authors: Satish Kumar, K, SivaSankar, P, Parveen Begum, S, Laxman, B, Mahesh Devidas, Phalke, Maha Laxmi Naidu, V, Solomon Raju, P, Srinagesh, D
Format: Article
Language:English
Subjects:
Analysis
Basins
Cratons
Crustal thickness
Depth
Digitization
Earth and Environmental Science
Earth Sciences
Earthquakes
Fault detection
Fault lines
Faults
Geological faults
Geology
Geophysical studies
Gravity data
Magnetic data
Microseisms
Quartzite
Sediment
Sediments
Seismic activity
Seismological data
Seismology
Shales
Sills
Software
Space Exploration and Astronautics
Space Sciences (including Extraterrestrial Physics
Spectral analysis
Spectrum analysis
Stone
Stratigraphy
Strike-slip faults
Thickness
Two dimensional models
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Summary:A ~60 km long Veldurti–Kalva–Gani (VKG) fault is one of the identified strike-slip faults extending from Eastern Dharwar Craton (EDC) to Cuddapah basin in South Indian Shield. The recorded recent seismic activity during year 2012–2016 show occurrences of three microseismic events (< M w 2.0) in the vicinity of this fault. Historically, no major seismic events are recorded near this fault except magnitude of 5.0–5.9 (1843) earthquake at about ~80 km west of this fault near Bellary. In the present study, analysis of available gravity, aeromagnetic and newly acquired ground gravity and magnetic data in the vicinity of the fault has been carried out to understand subsurface characteristics of this VKG fault and nearby structural features related to recent seismic activity. Analysis of aeromagnetic and gravity data shows shallow origin of the fault and earthquakes are associated with the zone of intersection like cross faults/lineaments which are parallel and perpendicular to the VKG fault. The calculated log normalized radially averaged power spectrum of the available gravity and aeromagnetic data shows four average depths h 0 (12.7 km), h 1 (6 km), h 2 (2.0 km) and h 3 (0.5 km). These estimated depths are possibly, bottom of the upper crust, thickness of the Cuddapah basin sediments, horizon of the basic sills, flows and the ferruginous quartzites and cumulative stratigraphic thickness of the Tadpatri shales and the Kurnools in the areas, respectively. The jointly inverted 2-D model from the ground gravity and aeromagnetic data along 2.7 km profile across VKG fault shows, faulting between Banganapalli Quartzite and Tadpatri Shales. The estimated average focal depth from the observed microseismic events is around 13 km. It is concluded from the present study that the observed microseismic events in the vicinity of VKG fault are associated with the intersection zones of cross faults/lineaments near the VKG fault and originated at an average depth of 13 km might be bottom of the upper crust. The estimated depths from the present analysis are well corroborated with previous geophysical studies. Highlights Mapping of Veldurti–Kalva–Gani fault through gravity, magnetic and aeromagnetic data which is associated with recent seismic activity. Understanding of origin of the seismic activity through spectral analysis. Estimation of depth to the basement, upper crust and thickness of Cuddapah basin sediments in the study region. Estimation of focal depth from seismologic
ISSN:2347-4327
0253-4126
0973-774X
DOI:10.1007/s12040-020-01519-5