Assessing earthquake catalogue completeness for Argentina and neighbouring countries

Abstract

The main objective of this article is to determine the completeness magnitude (CM) of the earthquake catalog for Argentina and neighbouring countries from 1524 to 2024. The CM was evaluated from a stable estimate of the average rate of earthquake occurrence and the temporal distribution of seismicity using the Stepp and Temporal Course of Earthquake Frequency (TCEF) methods. These methods provide an innovative approach to the analysis of the completeness level in the study area. Temporal variations of the CM in the past were also investigated, since no records were available before the 16th century.

The catalogue was filtered and homogeneized to moment magnitude (Mw). Results from the Stepp method showed that the CM significantly improved from 1960, whereas the TCEF method indicated a decrease of the CM from 1964. The Gutenberg and Richter (G-R) recurrence parameters a and b were also estimated for the entire catalog using the CM obtained from both methods, and for the cortical, intermediate and deep events using only the Stepp completeness. The b value obtained for the entire catalogue is 0.75 with the Stepp method and 0.66 with the TCEF method, very similar to the regional values determined in previous studies. It is necessary to highlight that the proposed approach provides a preliminary step for estimating the seismic hazard of the study area. The integration of other methods will help to improve some limitations, contributing to a complete assessment of the earthquake catalogue.