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Analysis and Proposal of Empirical Magnitude Scaling Relationships for Faults Seismic Potential in Central America

Description: 

Central America is a seismically active region where five tectonic plates (North America, Caribbean, Coco, Nazca, and South America) and the Panama Microplate interact, in a subduction zone with transform faults and near to triple points. This complex tectonic setting makes the estimation of the seismic potential (maximum magnitude: Mmax) a very important task. There are a series of empirical formulas and diagrams by means of which the seismic potential of faults can be estimated from rupture earthquake parameters. In this study, some of these formulas were applied to approximate the magnitude of earthquakes occurred in Central America, and own scaling laws are proposed. This has been accomplished based on the most complete data set of relevant and better characterized earthquakes generated by faults in the region, made up of 64 earthquakes between 1972 and 2021, with magnitudes between 4.1 and 7.7 Mw. The data set consists in a compilation of the seismic events and its relatively well-established rupture parameters (length, width, area, slip, magnitude) and characteristics (location, faults, aftershocks). These analyses allowed to determine which global equations fit best, and to propose new empirical relationships specific for Central America, for the rupture parameters of length, width, and rupture area. These relationships have been validated and logical trees are suggested that combine the proposals for the region and global equations. Based on this, 30 faults of Central America have been selected, for which its Mmax has been estimated considering a total rupture of the fault length mapped. According to that, the countries with more faults with Mmax > 7.0 Mw are Guatemala and Nicaragua. However, most of the faults studied present Mmax between 6.2 and 6.5 Mw, and this magnitudes for shallow earthquakes near to populated centers have already been damaging in the past in countries such as Costa Rica, El Salvador and Nicaragua. The proposed equations contribute as a very relevant step for the adequate characterization of faults aimed at seismic hazard assessment, both probabilistic and deterministic approaches.

Session: Active Faults in the Caribbean and Central America

Type: Oral

Date: 4/20/2023

Presentation Time: 02:45 PM (local time)

Presenting Author: María Belén Benito Oterino

Student Presenter: No

Invited Presentation: 

Authors