EAPSI: A Better Understanding of Shallow, Subduction Zone Earthquakes Through Bayesian Analysis: A Case Study of the 2015 Illapel, Chile Earthquake

Williamson Amy, Atlanta GA

Investigators

Abstract

On September 16, 2015, a Mw 8.3 earthquake ruptured a portion of the Peru-Chile trench. This event appears to have a temporally complex rupture and was well recorded by instruments both in the near-field and at teleseismic distances. The proposed project will apply an adaptive non-linear Bayesian inversion method to solve for the fault rupture of the recent Chilean earthquake, using the preponderance of collected data from both on-land measurements and ocean based tide gauge and tsunami recordings. This approach results in a quantification of the earthquake rupture through an explicit treatment of the data and model resolvability along a source region. The benefit of this type of inversion method compared to other conventional methods is that it gives a higher level of focus to the uncertainties in measurements and their spatial and temporal resolvability. This leads to an inversion result that has improved confidence levels without introducing biases in grid placement or problem regularization. This research will be conducted at the Australian National University School of Earth Sciences under the mentorship of Professor Phil Cummins. The Cummins group is noted for specialized expertise in seismology and tsunami wave propagation from a mathematical and geophysical perspective. On September 16, 2015, a large magnitude earthquake struck of the coast of Central Chile in a region that has been prone to very large and destructive earthquakes over the past decades. An Initial analysis of the spatial and temporal components of the rupture suggests that this event was complex in nature. In conjunction with research scientists at the Australian National University, this project proposes to quantify the slip from the 2015 Chile earthquake through use of a non-linear Bayesian adaptive inversion. This approach gives a higher level of focus on the uncertainties of each measurement used as well as their spatial and temporal resolvability. This results in a better understanding of how the earthquake ruptured while minimizing the amount of analyst led biases, which can greatly alter the model results. Ultimately, the results of this project allows for a better understanding of the seismic hazard of this region of the tectonically active Peru-Chile trench. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Australian Academy of Science.