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Published January 2016 | Published
Journal Article Open

Differences in Epicentral Location of Mexican Earthquakes between Local and Global Catalogs: An update

Abstract

Differences in epicentral locations between local and global catalogs for earthquakes in the Mexican subduction zone were first observed in 1980, based on a few well-studied events. In this writing the locations of two local catalogs are compared; (1) a recent high-precision catalog for the Guerrero area and (2) the National Seismological Service (SSN) catalog, against the United States Geological Service (USGS) global catalog. We found that on average the epicentral locations reported in global catalogs, for earthquakes of magnitudes greater than 5, generated in the Mexican subduction zone, are 26 km in the N54oE direction compared to those reported in local catalogs. We investigated how the error varies for different types of earthquakes in Guerrero and how these vary throughout the trench, from the state of Jalisco to Chiapas. On average, the differences are greater for reverse earthquakes that occurred near the trench and for events that occurred in Michoacán. The differences are larger on average for events of greater magnitude. There is a trade-off between distance to the trench and time, which indicates a low resolution for these parameters, due to the lack of stations located in the Pacific Ocean. The differences between the locations can be attributed to a systematic model in the velocity structure for the mantle, consistent with fast trajectories to the northeast and slow trajectories relative to the southwest. from the state of Jalisco to Chiapas. On average, the differences are greater for reverse earthquakes that occurred near the trench and for events that occurred in Michoacán. The differences are larger on average for events of greater magnitude. There is a trade-off between distance to the trench and time, which indicates a low resolution for these parameters, due to the lack of stations located in the Pacific Ocean. The differences between the locations can be attributed to a systematic model in the velocity structure for the mantle, consistent with fast trajectories to the northeast and slow trajectories relative to the southwest. from the state of Jalisco to Chiapas. On average, the differences are greater for reverse earthquakes that occurred near the trench and for events that occurred in Michoacán. The differences are larger on average for events of greater magnitude. There is a trade-off between distance to the trench and time, which indicates a low resolution for these parameters, due to the lack of stations located in the Pacific Ocean. The differences between the locations can be attributed to a systematic model in the velocity structure for the mantle, consistent with fast trajectories to the northeast and slow trajectories relative to the southwest. The differences are larger on average for events of greater magnitude. There is a trade-off between distance to the trench and time, which indicates a low resolution for these parameters, due to the lack of stations located in the Pacific Ocean. The differences between the locations can be attributed to a systematic model in the velocity structure for the mantle, consistent with fast trajectories to the northeast and slow trajectories relative to the southwest. The differences are larger on average for events of greater magnitude. There is a trade-off between distance to the trench and time, which indicates a low resolution for these parameters, due to the lack of stations located in the Pacific Ocean. The differences between the locations can be attributed to a systematic model in the velocity structure for the mantle, consistent with fast trajectories to the northeast and slow trajectories relative to the southwest.

Additional Information

© 2016 Union Fisica Mexicana. Received: June 06, 2015; accepted: November 12, 2015; published on line: December 31, 2015. We thank Harley Benz at the USGS for providing the residuals for recent earthquakes in Guerrero, as well as helpful information about the location process. We thank the National Seismological Service, and in particular Víctor Hugo Espíndola, for providing the earthquake catalog and helpful information about the location process. The study was funded in part by UNAM / DGAPA projects IB101812 (VH) and IN111314.

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Created:
August 22, 2023
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