Past Research Projects
Some of my past research projects (latest to earliest):
Ecuadorian margin and the 2016 Mw 7.8 Pedernales earthquake
In April 2016 a Mw 7.8 earthquake struck the coast of Ecuador. The subsequent aftershock seismicity represented a unique opportunity to study in detail this subduction zone. Shortly after the mainshock we deployed a temporary array of land and offshore stations (paper).
We found a spatio-temporal dependency of aftershocks with afterslip and a correlation between the distributions of seismic/aseismic slip and bathymetric anomalies. To explain our observations, we propose a model in which the Ecuadorian margin is subject to a bimodal slip mode, with distributed seismic and aseismic slip mechanically controlled by the subduction of rough oceanic relief (paper).
Additionally, we also used aftershock seismicity to infer the velocity structure in the region (paper).
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Source properties of a small-magnitude induced seismic sequence in Brazil
My last project in Brazil involved the investigation of earthquake source properties of an induced seismic sequence located in the southeast of the country. In this area, small magnitude earthquakes were triggered after the excavation of water wells for irrigation purposes. We accurately relocated the sequence and calculated source properties such as corner frequencies, stress drop and moment magnitudes using an empirical Green’s functions (EGF) method. We found low absolute stress drops (<1 MPa) and increase of stress drop with seismic moment (Mw<2). We explain our observations as due to repeated rupture on a fault patch at shallow depth, following continuous inflow of water. See papers: Bebedouro1 Bebedouro2.
Tailings dam failure in SE Brazil and preceding seismic sequence
The collapse of a mine tailings dam and subsequent flood in SE Brazil on 5 November 2015 was preceded by a small-magnitude seismic sequence. In this report, we explore the spatio-temporal associations between the seismic events and the accident and discuss their possible connection. We also analyze the signals generated by the turbulent mudflow, as recorded by the Brazilian Seismographic Network (RSBR). In light of our observations, we propose as possible contributing factor for the dam collapse either ground shaking and/or soil liquefaction triggered by the earthquakes. The possibility of such a small-magnitude earthquake contributing to the collapse of a tailings dam raises important concerns regarding safety and related legislation of dams in Brazil and the world. Paper here.
2015 Bucaramanga, Colombia, intermediate-depth earthquake
Together with researchers at the MIT, we studied the complex rupture process of an intermediate-depth earthquake in Colombia. The resulting seismic radiation is interpreted as resulting from an extreme weakening due to a cascading thermal shear runaway, with an initial inefficient radiation process followed by a fast and dynamic efficient rupture. Our results imply dynamic complexity of the seismic rupture deep inside the Earth, and may help to give some new insights about the physical mechanism of intermediate-depth earthquakes. Paper here.
Mid-plate South America seismicity and its correlation with lithospheric properties
In 2014, I worked on a study of crustal seismicity in mid-plate South America, looking for statistical correlations between seismicity occurrence and several lithospheric geological/geophysical properties. This study has broad implications for the understanding of intraplate seismicity in the world, and it was published on a Special Volume of the Geological Society of London. See paper.
2012 Montes Claros, Brazil, seismic sequence
As part of my first post-doc project at the University of São Paulo back in 2013, I studied a small magnitude seismic sequence that occurred in the middle of the São Francisco Craton, Brazil. This was my first approach to intraplate crustal seismicity, as opposite to my previous studies on the Chilean active margin. I characterized the Montes Claros sequence by accurately locating the earthquakes, obtaining the fault plane, calculating focal mechanisms and finally determining the predominant stress field in the area. These results were published here.
2010 Chile Earthquake Aftershocks
After the occurrence of the Mw 8.8, 2010 Chile earthquake, I redirected the second half of my PhD to characterize the aftershocks of the 2010 Chile earthquake through regional moment tensor inversions. Our study provides insight into the mechanics of the seismic afterslip pattern of this large megathrust earthquake and a quantitative approach to the distribution of aftershocks relative to coseismic slip that can be used for similar studies in other tectonic settings. The results of this research were published as two separate papers in GRL and EPSL.
2007 Aysén Fjord Seismic Sequence
I dedicated the first half of my PhD to the study of a sequence of seismic events that occurred in the Patagonian fjord-lands of Southern Chile, related to the reactivation of the Liquiñe-Ofqui Fault. This area, historically believed to be a “seismically quiet” region of Chile, was the focus in 2007 of hundreds of earthquakes, the largest being a Mw 6.2 tsunamigenic earthquake that killed 7 people. My study here focused on the characterization of the foreshock/aftershock sequence including the inversion for the first time of a local velocity model for the area, probabilistic location of the events, and computation of focal mechanisms. The results of this research were published here.
Chile Triple Junction Region Seismicity
For my Geology degree thesis in Chile, I worked on the regional seismicity of the area in front of the Chile Triple Junction, providing for the first time a catalogue of local seismicity for that remote region of the world. The results of this research were published here.