University of Liverpool

Graduate Student, School of Environmental Sciences

Thesis Title: The February 2010 Chile megathrust earthquake: investigation of relaxation processes and time-dependent changes in seismic properties

About

My thesis is centered on studying the February 2010 Maule, Chile earthquake; this was the sixth largest earthquake ever to be recorded. This project will examine how Earth's internal structure beneath Chile changed as a result. Such a detailed study has never been performed. This project will, therefore, not only advance our understanding of Earth structure, but also help us to understand the dynamics of large earthquakes, important for hazard mitigation.

Approximately 70% of all global seismic energy is released in earthquakes with similar characteristics; these predominately occur around the Pacific 'Ring of Fire'. Normally, with this size of earthquake we expect aftershocks to continue for several years following the earthquake. Although we have observed a large number of these, there has been an abnormally low number of large magnitude aftershocks, which can cause significant damage and casualties. This project will study the distribution of aftershocks and explore whether a seismic hazard still remains for this area of Chile. Prior to the earthquake, this region was a known seismic gap: it had not seen a large earthquake since 1835. Many seismic gaps are present today; two important examples being northern Chile and Parkfield, California.  Knowledge of the time-varying processes could therefore have enormous implications for our knowledge of the reasons and the mechanisms of earthquake rupture and their natural cyclicity. Regions of high seismic hazard often lie close to active volcanic belts; one such area is South America. Workers have proposed that large earthquakes can trigger volcanic eruptions, however evidence for this is sparse. With the expected high resolution picture of the subsurface, this study could shed light on this relationship by studying changes in properties below known volcanoes. Although the 2004 Boxing Day and 2011 Japan seismic events were greater, they give us a limited view on the processes that occurred because their epicentres were offshore, whereas the Chile earthquake is unique because it was located onshore, so far more detailed information is available.