Lab Earthquakes Show How Grains at Fault Boundaries Lead to Major Quakes
06-07-22
By simulating earthquakes in a lab, Caltech engineers have provided strong experimental support for a form of earthquake propagation now thought responsible for the magnitude-9.0 earthquake that devastated the coast of Japan in 2011. "Our novel experimental approach has enabled us to look into the earthquake process up close, and to uncover key features of rupture propagation and friction evolution in rock gouge," says Vito Rubino, research scientist and lead author of the Nature paper. The Nature paper is titled "Intermittent lab earthquakes in dynamically weakening fault gouge." Rubino and his co-authors Nadia Lapusta, Lawrence A. Hanson, Jr., Professor of Mechanical Engineering and Geophysics, and Ares Rosakis, Theodore von Kármán Professor of Aeronautics and Mechanical Engineering, show that so-called "stable" or "creeping" faults are not actually immune to major ruptures after all, as previously suspected. [Caltech story]
Tags:
research highlights
GALCIT
MCE
Ares Rosakis
Nadia Lapusta
Vito Rubino
Winners of the 2021 Demetriades - Tsafka - Kokkalis Prizes Announced
06-15-21
The student winners of the 2021 Demetriades - Tsafka - Kokkalis Prizes were announced at the end of this academic year. David Brown, advised by Professor Viviana Gradinaru and Professor Matt Thomson has received the prize in Entrepreneurship. His research is in molecular and computational strategies for both understanding variability in the human immune system, and characterizing the on- and off-target profile of gene therapy delivery at the resolution of individual cells. Hsiao-Yi Chen, advised by Professor Marco Bernardi has received the prize in Nanotechnology. His research is in the development of ab initio methods to investigate exciton radiative emission and ultrafast dynamics. Tatyana Dobreva, advised by Professor Matt Thomson and Professor Viviana Gradinaru has received the prize in Entrepreneurship. Her research is in single-cell sequencing to interrogate the human immune system, characterize immune response to recombinant Adeno-Associated Viruses (AAVs), and engineer immune cells. Zachary Lee, advised by Professor Steven Low has received the prize in Environmentally Benign Renewable Energy Sources. His research involves developing a suite of tools and algorithms to enable smart electric vehicle charging at scale. Valère Lambert, advised by Professor Nadia Lapusta has received the prize in Seismo-Engineering, Prediction, and Protection. His research is in developing and using physics-based numerical models that combine laboratory insight and theoretical developments to simulate sequences of earthquake ruptures and slow slip that match field observations, thus illuminating physical properties of faults and building towards predictive modeling.
Tags:
honors
Demetriades - Tsafka - Kokkalis Prizes
Nadia Lapusta
Steven Low
Marco Bernardi
Viviana Gradinaru
Valère Lambert
Matt Thomson
David Brown
Hsiao-Yi Chen
Tatyana Dobreva
Zachary Lee
Untangling the Heat Paradox Along Major Faults
03-12-21
Nadia Lapusta, Lawrence A. Hanson, Jr., Professor of Mechanical Engineering and Geophysics, and graduate student Valère Lambert, seek to explain the size of the forces acting on "mature faults"—long-lived faults along major plate boundaries like the San Andreas Fault in California—in an effort to better understand the physics that drive the major earthquakes that occur along them. Understanding the physics that govern major earthquakes on different types of faults will help generate more accurate forecasts for earthquake threats. "We have a lot of data from large earthquakes along subduction zones, but the last really major earthquakes along the San Andreas were the magnitude-7.9 Fort Tejon quake in 1857 and the magnitude-7.9 San Francisco Earthquake in 1906, both of them before the age of modern seismic networks," Lapusta says. [Nature article] [Caltech story]
Tags:
research highlights
MCE
Nadia Lapusta
Valère Lambert
The Moving Earth, Micro to Mega
01-18-19
Nadia Lapusta, Professor of Mechanical Engineering and Geophysics, creates computer models of earthquakes by integrating an astonishing range of data—on scales from thousands of kilometers down to microns and from millennia down to thousandths of a second. “You have to understand the mechanics across the entire earthquake system, starting at the micrometer scale,” says Professor Lapusta. “This is the challenge.” Her numerical models rely upon field observations, seismic monitoring, lab experiments, and theoretical science, while complementing those endeavors with a new perspective. The predictions expand researchers’ view beyond the limits of direct observation—which is important for events that occur across thousands of years. [Breakthrough story] [ENGenious story]
Tags:
research highlights
MCE
Nadia Lapusta
Professor Lapusta Receives GSC Mentoring Award
09-17-18
The Caltech Graduate Student Council (GSC) has selected Professor Nadia Lapusta as the recipient of the 2017-2018, GSC Mentoring Award. The GSC Teaching and Mentoring Awards recognize individuals “who have an extraordinary impact on Caltech graduate students through their roles as teachers and mentors.” Nominators described Professor Lapusta as being an excellent cheerleader who fosters her students' ties with the community. Despite leading a large group, she makes significant amounts of time for her students. One student said, "the path ahead always seems more optimistic after our meetings."
Tags:
honors
MCE
Nadia Lapusta
teaching
How Friction Evolves During an Earthquake
08-15-17
Professor Ares Rosakis, and colleagues including Professor Nadia Lapusta and Research Scientist Vito Rubino, are studying the way friction changes along a fault during a seismic event by simulating quakes in a lab. "Our unique facility … allows us for the first time to study friction point-wise and without having to assume that sliding occurs uniformly, as is done in classical friction studies," Rosakis explains. Professor Lapusta adds, “some numerical models of earthquake rupture … have used friction laws with slip-velocity dependence… It is gratifying to see those formulations validated by the spontaneous mini-earthquake ruptures in our study. " [Caltech story]
Tags:
research highlights
GALCIT
MCE
Ares Rosakis
Nadia Lapusta
Vito Rubino
Microseismicity and Large Earthquakes
06-10-16
Nadia Lapusta, Professor of Mechanical Engineering and Geophysics, and Caltech alumnus Dr. Junle Jiang, have linked the patterns of microseismicity to the depth extension of large earthquakes, both through modeling and observationally. They argue that fault segments which do not have concentrated microseismicity at the bottom of the seismogenic zone must have had deeper, larger earthquakes than currently believed. A number of segments on the San Andreas fault appear to fall into that category. The potential for such deeper earthquakes in the future would imply higher seismic hazard. [Science article] [KPCC coverage] [New Yorker Article]
Tags:
research highlights
MCE
Nadia Lapusta
alumni
Junle Jiang