Abstract
Recently, amid the pandemic of COVID-2019, the north-east Delhi region experienced two small earthquakes in a short span of 1 month; the first occurred on 12th April 2020 (Mw 3.5) and the other on 10th May 2020 (Mw 3.4). These events were followed by 4 aftershocks of magnitude Mw ≤ 3.0. We carried out morphotectonic (high stream length-gradient index) and static Coulomb stress failure analyses to delineate the hidden causative fault(s) in the region. In the study, ASTER DEM data of 30 m resolution and Survey of India (SoI) toposheets on 1:50,000 scales were used for morphotectonic analysis. The analysis depicted a very high stream length-gradient (SL) and fall in elevation in the epicentral area, suggesting the area to be tectonically active with a NE-SW trending fault line. In addition, the nature of static Coulomb failure stress contours for both the main events, Mw 3.5 and Mw 3.4, suggests an NNE-SSW trending high Coulomb stress regime. Such a high coulomb stress regime is obvious at the location where a high SL index and fall in elevation were marked, which clearly indicates the presence of NNE-SSW trending a causative fault, named ‘Khanpur-Japti fault’.
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We are thankful to the National Centre for Seismology, Ministry of Earth Sciences for permitting us to publish the research work. Comments and suggestions offered by AP Pandey and the reviewer helped in improving the MS.
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Bansal, B.K., Mohan, K., Ul Haq, A. et al. Delineation of the Causative Fault of Recent Earthquakes (April–May 2020) in Delhi from Seismological and Morphometric Analysis. J Geol Soc India 97, 451–456 (2021). https://doi.org/10.1007/s12594-021-1711-5
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DOI: https://doi.org/10.1007/s12594-021-1711-5