17:15 〜 19:15
[SCG45-P24] Shallow Tectonic Tremors in the Southeastern Guerrero Seismic Gap and a Comparison of Envelope Correlation Methods.
A seismic gap exists along the southern coast of Guerrero, Mexico, where no large earthquakes have been observed in over 100 years. This region is known as the "Guerrero seismic gap". While shallow tremors have been detected in the northwestern segment of the Guerrero seismic gap (Plata-Martinez et al., 2021), no tremors have been observed in its southeastern part.
In this study, we conducted the first detection of tremors in the southeastern Guerrero seismic gap and characterized their spatiotemporal activity. For event detection and source location, we employed two types of envelope correlation methods (Ide, 2010; Mizuno and Ide, 2019). Tremors were extracted based on their durations, the presence of distinct P- and S-wave phases, and their dominant frequency bands.
The spatial characteristics of the tremors were similar between the two methods; however, their temporal characteristics differed. This suggests that each method may be more sensitive to certain waveform features and/or variations in the tremor duration estimation.
Combining both results from two methods, we identified that tremors were primarily located on the eastern and western edges of the network, with fewer occurrences near its center, in the southeastern Guerrero seismic gap. Furthermore, tremor activity increased after late September 2022. The southeastern area tends to have relatively higher residual gravity anomalies than the northwestern area, which can be interpreted as heterogeneity in the shallow plate interface topography. This heterogeneity is likely a contributing factor to the difference in the tremor distribution between the two regions.
In this study, we conducted the first detection of tremors in the southeastern Guerrero seismic gap and characterized their spatiotemporal activity. For event detection and source location, we employed two types of envelope correlation methods (Ide, 2010; Mizuno and Ide, 2019). Tremors were extracted based on their durations, the presence of distinct P- and S-wave phases, and their dominant frequency bands.
The spatial characteristics of the tremors were similar between the two methods; however, their temporal characteristics differed. This suggests that each method may be more sensitive to certain waveform features and/or variations in the tremor duration estimation.
Combining both results from two methods, we identified that tremors were primarily located on the eastern and western edges of the network, with fewer occurrences near its center, in the southeastern Guerrero seismic gap. Furthermore, tremor activity increased after late September 2022. The southeastern area tends to have relatively higher residual gravity anomalies than the northwestern area, which can be interpreted as heterogeneity in the shallow plate interface topography. This heterogeneity is likely a contributing factor to the difference in the tremor distribution between the two regions.