Application of the double difference earthquake relocation algorithm methodology using hypodd at four seismic sequences in Costa Rica

[摘要] Several seismic sequences occur during a year in Costa Rica. When registered at the National Seismological Network, each earthquake is located to update the national catalog. The analysis and characterization of the sequence clusters is then done by manual relocation only. This study includes four sequences, post-processed by manual location, event cross-correlation, and cluster relocation with a double difference algorithm; this, to give a more accurate location of the source. The sequences processed consist of 21 to 64 earthquakes, and occurred in a period of 3 to 21 days. Each event was registered in at least 27 stations, with 105º of station coverage, and a maximum hypocentral distance of 11 km between events. After the manual relocation, the quality of the event locations was analyzed to fulfill the requirements for the event cross-correlation and the double difference methodology. The results show a reduction from two to twenty times the initial hypocentral distance, also in the relative error for each individual event that help reduce the source area for each sequence.

[学科分类] 地质学

[关键词] Double difference algorithm;cross-correlation;seismic sequence;earthquake;upper crust seismicity.