Ground motion simulations produced by newly identified potentially active crustal faults in Chile.

Abstract

Newly identified potentially seismogenic crustal faults (PSCF) might pose significant risk to numerous locations in continentalChile. Much of the PSCF identification work has been done within the framework of the South America Risk Assessment Projectof the Global Earthquake Model (SARA). Unfortunately, there are very few ground motion recordings produced by earthquakes onthese faults, with magnitudes significantly lower than the ones of interest for engineering applications. To quantify the hazard thesePSCF create, we have turned to a physics-based approach to simulate ground motion produced by potential earthquakes on thesefaults. With the ground motion recordings of the Centro Sismológico, Nacional (CSN), we have estimated path and site attenuationparameters, namely kappa, in Chile. Preliminary results show that the value of kappa is approximately 40 ms. The PSCF databasecontains variable information depending on the different sources used to compile and filter the fault datum. Nevertheless, if absent,the necessary parameters to simulate seismic scenarios such as the dimension, sense of slip and dip angle and direction can beextracted from the fault traces themselves and inferred from the seismotectonic and geologic setting of each individual fault.We used the 2010 Leonard scaling relationships to determine a magnitude based on the length of each potentially seismogenicfault. For each fault, we computed several kinematic earthquake rupture scenarios, and propagated seismic waves using Green’sfunctions with the UCSB method (Crempien and Archuleta, 2015). The Green’s functions incorporate the attenuation measuredpreviously, and are calculated up to 25 Hz. Interestingly, for many earthquake scenarios, we estimated peak ground accelerationintensities of 1 g within 10 km of the closest distance to the fault, well above the design standards for which most of the country’scritical infrastructure has been designed. These results emphasize the need to further study PSCF, their seismic-rate and thehazard they pose to our country