Damage assessment of the 2015 Mw 8.3 Illapel earthquake in the North-Central Chile

Abstract

Destructive megathrust earthquakes, such as the 2015 Mw 8.3 Illapel event, frequently affect Chile. In this study, we assess the damage of the 2015 Illapel Earthquake in the Coquimbo Region (North-Central Chile) using the MSK-64 macroseismic intensity scale, adapted to Chilean civil structures. We complement these observations with the analysis of strong motion records and geophysical data of 29 seismic stations, including average shear wave velocities in the upper 30 m, Vs 30 , and horizontal-to-vertical spectral ratios. The calculated MSK intensities indicate that the damage was lower than expected for such megathrust earthquake, which can be attributable to the high Vs 30 and the low predominant vibration periods of the sites. Nevertheless, few sites have shown systematic high intensities during comparable earthquakes most likely due to local site effects. The intensities of the 2015 Illapel earthquake are lower than the reported for the 1997 Mw 7.1 Punitaqui intraplate intermediate-depth earthquake, despite the larger magnitude of the recent event.

Revisiting the 2015 Mw=8.3 Illapel earthquake: Unveiling complex fault slip properties using Bayesian inversion.

“…waves reaching more than 4 m high in Chile Fern ández et al 2019 ). The thrust focal mechanism is consistent with the rupture of the megathrust interface (Ekstr öm et al 2012 ).…”

Revisiting the 2015 Mw=8.3 Illapel earthquake: Unveiling complex fault slip properties using Bayesian inversion.

“…The latest megathrust earthquake in Chile is the 2015 M W = 8.3 Illapel earthquake, which occurred off the west coast of the Coquimbo region on September 16th, 2015, at 22:54:31 UTC (Centro Sismológico Nacional, CSN) (Li et al 2016;Ruiz & Madariaga 2018). The 2015 Illapel earthquake initiated at a depth of 23 km and triggered a trans-pacific tsunami with waves reaching more than 4 meters high in Chile Fernández et al 2019). The thrust focal mechanism is consistent with the rupture of the megathrust interface (Ekström et al 2012).…”

Early Stage and Main Ruptures of the 2015 Mw8.3 Illapel, Chile, Megathrust Earthquake: Kinematic Elliptical Inversions and Dynamic Rupture Simulations

“…For example, the 1730 event had a magnitude of ∼9.0 (Carvajal et al., 2017; Udias et al., 2012). Modeling the dynamic rupture of such large subduction earthquakes is one of the most important issues for understanding not only the long‐term subduction process but also the severe ground motions observed in cities close to rupture zones (Fernandez et al., 2019) and associated tsunami impacts (e.g., Aránguiz et al., 2016; Fuentes et al., 2017; Heidarzadeh et al., 2016; Lay et al., 2016) for quantitative seismic hazard analysis.…”