Abstract
Abstract The Shillong Plateau (SP) and adjoining regions are one of the world’s most seismically active regions and to conduct a thorough seismological investigation and improved seismic hazard assessment, an updated and unified earthquake catalog is a prerequisite. In the present study, we compiled a homogeneous declustered earthquake catalog for the SP and adjoining regions by utilizing updated earthquake data from various international and national databases and pertinent literature for the period 825–2024, which consists of 6877 earthquakes. Employing the generalized orthogonal regression, orthogonal distance regression, standard least square regression, and inverted standard least square regression methods, 30 empirical relations have been derived to achieve magnitude homogeneity. All the reported magnitudes are converted into moment magnitude (Mw) using the derived regression relations. Subsequently, the declustering of the compiled homogenous earthquake catalog has been carried out using three techniques to distinguish dependent and independent earthquakes. Three approaches are used to assess the completeness of the nondeclustered and declustered earthquakes in terms of time and magnitude. The compiled updated and unified catalog in the present study contains 6877 earthquakes of Mw≥3.5 for the period 825–2024 obtained out of a total of 19,499 earthquakes reported from all sources. The completeness periods of the GK74 declustered earthquake catalog obtained by the cumulative visual inspection method for different magnitudes range from 14 to 218 yr and by Stepp’s method, it ranges from 15 to 215 yr. The spatial distribution of the magnitude of completeness (Mc), cumulative a-value, and b-value of the GK74 declustered earthquake catalog varies from 4.71 to 4.99, 5.64 to 10.17, and 0.68 to 1.63, respectively. The compiled updated and unified earthquake catalog is expected to be an essential input for regional seismicity, earthquake hazard, seismotectonic, and seismic hazard analysis of the SP and adjoining region.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call