Rapid early afterslip characteristics of the 2010 moment magnitude (Mw) 8.8 Maule earthquake determined with sub-daily GPS solutions

Abstract

Ground surface deformations can be observed during the coseismic and postseismic periods. The accurate determination of displacements is of paramount importance for the assessment of the destructive power of large earthquakes and the characterization of fault behaviors. Therefore, we employ the sub-daily Global Positioning System (GPS) solutions at 19 GPS stations to determine the coseismic and postseismic deformations of the 2010 moment magnitude (Mw) 8.8 Maule earthquake. Using sub-daily GPS data, we can accurately measure both coseismic and early postseismic deformation signals, which can precisely identify the distribution of coseismic slip and the spatiotemporal evolution of early afterslip within the first 36 h. In particular, the sub-daily solution can provide more accurate and quicker results, nearly 10% smaller than those with the daily solution. Furthermore, there is significant ground motion in the immediate postseismic period, which decreases rapidly thereafter. The largest postseismic deformation observed during the first 2 h occurred at station CONZ and amounted to 3.6 cm. During the immediate postseismic period of the 2010 Maule earthquake, afterslip is the dominant mechanism, while poroelasticity plays a negligible role within the first 36 h. Meanwhile, early aftershocks tend to occur in the boundary and the inner part of the afterslip, indicating that the afterslip has the potential to drive the occurrence of aftershocks in the initial stages of postseismic activity.