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Turkish Journal of Earth Sciences

DOI

10.55730/1300-0985.1920

Abstract

We present a detailed one-dimensional (1-D) velocity model of the Lake Van Basin and its surrounding region, alongside precise hypocenter locations, utilizing seismic data from the aftershocks of the 23 October 2011 Lake Van earthquake (Mw = 7.1). The 1-D minimum velocity model is computed by the VELEST program by analyzing body wave traveltimes and station corrections. Encompassing a geographical area of 180 × 90 km² centered around Lake Van, the study incorporated seismic data from 10 newly deployed stations, complementing the existing network of the Kandilli Earthquake Research Institute. A comprehensive manual analysis was conducted on a dataset comprising 7643 events occurring between 23 October 2011 and 21 January 2015. Among these, 1193 well-located events recorded by 16 stations were selected, encompassing 48,387 P-wave and 26,913 S-wave arrival times. The iterative simultaneous inversion technique was applied to refine velocity and hypocenter parameters while mitigating the influence of near-surface velocity heterogeneity and station elevation through station corrections. The resulting 1-D velocity model delineates eight distinct layers up to a depth of 39 km, including a 3-km-thick sedimentary layer, while determining the VP/VS ratio for each layer. Rigorous testing procedures were implemented to ensure the stability and accuracy of the velocity structure and aftershock locations. The relocation of the aftershock sequence using the new 1-D velocity model revealed significant shifts in the distribution pattern, notably concentrating relocated events towards the vicinity of the main shock area. This study underscores the efficacy of the VELEST software in deriving a robust 1-D velocity model and refining hypocenter locations for the Lake Van region. The insights gained enhance our understanding of the region's seismotectonic and have implications for seismic hazard assessment and risk mitigation strategies.

Keywords

Van earthquake, crustal model, relocation, 1-D velocity model, VP/VS ratio, Lake Van

First Page

407

Last Page

429

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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