10:45 〜 12:15
[SCG45-P27] Low-Frequency Aftershocks in The Pichilemu crustal fault system during the post-seismic period of the 2010 Mw8.8 Maule Earthquake
In recent years, attempts have been made to establish the relationship or connection between aseismic and seismic slip in space and time, especially in the afterslip of large megathrust earthquakes. It is known that afterslip is a product of ordinary earthquakes (aftershocks) and aseismic slip. However, it has not been possible to clarify what type of signal (seismic or aseismic) predominates over time, what mechanisms generate them, and why they are separated spatially. For this reason, we study the post-seismic behavior of the 2010 Mw 8.8 Maule earthquake, specifically in the area near Pichilemu Fault System (PFS), in order to characterize the seismic behavior of this area after this mega-earthquake. Using two dense networks of temporal stations, IMAD and Chile RAMP, which were active several months after the mainshock, we built a robust catalog of events using the envelope and cross-correlation techniques. Then, we relocated them manually to identify potential low-frequency aftershocks (LFAs) and ordinary earthquakes locations around the PFS area. Analyzing the frequency content of the earthquakes, preliminary results show differences in the behavior of these two kinds of events. For earthquakes of similar duration, magnitude and location, we observed different frequency behaviors, some controlled by high frequencies as usual in ordinary earthquakes and others dominated by low frequencies (possible LFAs). These first results suggest that the afterslip of the Maule earthquake could be concentrated in the interface as well as in the PFS. Furthermore, this could indicate a heterogeneous seismogenic behavior of the PFS, indicating possible mechanical, frictional, or rheological variations in the fault during the afterslip of the Maule earthquake.