Seismology / Geophysics

Associate Professor

Departamento de Geociencias

Facultad de Ciencias

Universidad Nacional de Colombia - Sede Bogotá

 

Visiting Professor

Earth, Atmospheric, and Planetary Sciences

MIT 

Address : Cra 30 # 45 - 03
Bogotá, Colombia

Ed. Manuel Ancizar Of. 302
Phone: (+57-1) 316 - 5000 Ext. 16530
E-mail: gaprietogo@unal.edu.co

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I am Associate Professor at the Departamento de Geociencias, Facultad de Ciencias in the Universidad Nacional de Colombia. I am also a Visiting Professor in the Department of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology. My research focuses on understanding the diversity of earthquakes and the associated ground motions expected on the surface of the Earth.

I received my PhD from Scripps Institution of Oceanography at UC San Diego working with Peter Shearer and Frank Vernon on scaling properties of earthquakes using state-of-the-art signal processing on some of the largest datasets at the time. I was a Thompson Postdoctoral Fellow at Stanford University working on seismic tomography and ground motion predictions using the ambient seismic field. Prior to my appointment at Universidad Nacional, I was a faculty member at MIT and before that faculty and head of the Geosciences program at Universidad de los Andes. I have also been a Visiting profesor at IPGP in 2012, and now at MIT. 

My main interest is to use seismic records to understand the earthquake source, the interior of the Earth and how both affect the ground motions that we feel on the Earth's surface. Seismological observations are affected by the internal structure of the Earth, for example amplification of seismic waves in sedimentary basins. The nature of the earthquake source has also a significant impact on ground motions, and I am interested in a better understanding of earthquake ruptures, i.e., are large earthquakes different from the more common small ones?

Current research projects can be found here.

Recent Publications 

Beneath southwestern Colombia, intermediate‐depth earthquakes in the Cauca cluster locate in the subducting Nazca plate and in two columns extending ~40‐km into the mantle wedge above the slab. Focal mechanisms have various faulting types and variably oriented nodal planes. We invert the focal mechanisms of the intraslab earthquakes for the intraslab stress field but cannot fit the region with a homogeneous stress tensor. We find that the principal stress axes rotate with the slab geometry, which has a concave shape and increases in dip angle from north to south. Deviation from a typical downdip extensional stress field may result from a buoyant young slab, an eastward mantle flow push, and/or along‐strike compression from the concave shape of the slab. The mantle wedge earthquakes also have various focal mechanisms but tend to have a subvertical nodal plane that aligns with the earthquake locations.

Chang, Y., Warren, L., Zhu, L. Prieto, G. A. (2019). Earthquake focal mechanisms and stress field for the intermediate-depth Cauca cluster, Colombia. J. Geophys. Res. Solid Earth, 124, 822-836.
 

Despite being a common feature of global seismicity, intermediate-depth earthquakes and their physical mechanism are not well understood. These earthquakes occur at pressures and temperatures incompatible with our current models of brittle failure. At those depths, most subducting slabs feature two separate layers of seismicity, with little activity in‐between. It is commonly believed that the release of high‐pressure fluids enables the brittle‐like behavior; however, it is not yet clear whether this mechanism can operate on both layers. We study the geometrical structure of the two layers and their statistical characteristics. Our results point to a relatively dry lithospheric mantle and suggest that the

physical mechanism enabling rupture in the lower layer is fundamentally different from the one in the upper.

Florez, M. Prieto, G. A. (2019). Controlling factors of seismicity and geometry in double seismic zones. Geophysical Res. Lett., 46, 4174-4181.

Curriculum Vitae (PDF)

Education 
2007 Ph.D. (Earth Sciences) UC San Diego 
2004 M. Sc. (Earth Sciences) UC San Diego 
2002 B.S. (Geology) Universidad Nacional de Colombia

Professional Experience 
2017 - Present
  Associate Professor - Universidad Nacional de Colombia

2016 - 2017      Associate Professor - Universidad del Rosario

2013 - 2016      Assistant Professor - MIT
2009 - 2013      Assistant Professor - Universidad de los Andes
2007 - 2008      Thompson Postdoctoral Scholar, Stanford University 
2002 - 2007      Graduate Student Researcher UC San Diego

External Service 

 

2013 - Present  Associate Editor J. Geophysical Research (Solid Earth)

2019 - 2020      AGU Fall Meeting Program Committee - Seismology

2016 - 2017      Keiiti Aki Award Committee Member AGU Seismology Section 

Honours 
2010 Keiiti Aki Young Scientist Award (video
2011 Editors Citation for Excellence in Refereeing, JGR-Solid Earth, AGU

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