Abstract

CAMPOS-DURAN, Daniela; QUINTERO-QUINTERO, Ronnie  and  SEGURA-TORRES, Juan. San Gabriel earthquake, July 27, 2018 (Ml 4.6): seismic source parameters and the seismic context of the southwestern region of the Central Valley of Costa Rica. Bol. geol. [online]. 2021, vol.43, n.3, pp.165-178.  Epub Apr 02, 2022. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v43n3-2021008.

In this research the seismic source parameters of the earthquake that occurred on July 27, 2018, at 17:50:46 (UTC time) in San Gabriel de Aserrí (latitude 9.788, longitude -84.101) are characterized and analyzed. The parameters show that the event had a depth of 15 km and Ml 4.6. The distribution of localized seismicity and a focal mechanism solution indicates that it probably occurred on a right-lateral strike-slip fault with a small normal component, strike NNW, high dip angle ~77°, dipping to the NE (strike 326 ° /dip 77 ° /slip -165°). The focal mechanism is consistent with those of previous seismicity located in the area and they indicate transtensional deformation in the central forearc of the country, known as the Central Costa Rica Deformed Belt. The instrumental intensities, obtained from the acceleration (% g) recorded in the seismic stations, allowed to identify in the Modified Mercalli Intensity scale (MMI) maximum instrumental intensities of IV in communities such as San Gabriel de Aserrí, San Pablo de León Cortés, and San Marcos de Tarrazú.

Keywords : Costa Rica; San Gabriel earthquake; Moment tensor; Aftershocks.

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