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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

Winners of the 2016 Demetriades - Tsafka - Kokkalis Prizes Announced

06-09-16

The student winners of the 2016 Demetriades - Tsafka - Kokkalis Prizes were announced at a special dinner with the Demetriades - Tsafka – Kokkalis family. Rachel P. Galimidi received the prize in Biotechnology for her work with Professor Pamela Bjorkman aimed to further understand the mechanism of HIV evasion of the humoral immune response. Junle Jiang was the recipient of the prize in Seismo-Engineering, Prediction, and Protection for his work with Nadia Lapusta which used probabilistic inversion tools to understand the deep-ocean trench generated tsunamis that occurred during the subduction-zone earthquakes in Japan and Chile. Yinglu Tang working with Dr. Jeff Snyder received the prize in Environmentally Benign Renewable Energy Sources for her work on thermoelectric skutterudites for mid-temperature applications such as automotive waste heat recovery. The second winner in this category was Changhong Zhao who worked with Professor Steven Low to study the control and optimization of modern electric power systems. The winner of the prize in Nanotechnology was Gustavo Rios whose research involves development of a modular, scalable, nanofabricated neural probe system for dense 3-D electrophysiology to study animal brains. Rio’s graduate advisor was Professor Thanos Siapas. The prize in Entrepreneurship was given to Anton A. Toutov who was advised by Professor Robert Grubbs. His research interests lie in using fundamental chemistry to development radically new, sustainable ways to make everyday chemical products and generate clean energy.

Tags: APhMS EE honors MedE MCE CMS Jeff Snyder Nadia Lapusta Steven Low Robert Grubbs CNS Junle Jiang Rachel P. Galimidi Pamela Bjorkman Yinglu Tang Changhong Zhao Gustavo Rios Thanos Siapas Anton Toutov

Winners of the 2015 Demetriades - Tsafka - Kokkalis Prizes Announced

06-09-15

The student winners of the 2015 Demetriades - Tsafka - Kokkalis Prizes were announced at a special luncheon with the Demetriades - Tsafka – Kokkalis family. Alborz Mahdavi received the prize in Biotechnology for his work with David Tirrell developed a set of important new tools for analyzing protein synthesis in complex biological systems. Srivatsan Hulikal was the recipient of the prize in Seismo-Engineering, Prediction, and Protection for his work with Nadia Lapusta on linking macroscopic frictional properties of interfaces to their micromechanics. Lingwen Gan working with Steven Low received the prize in Environmentally Benign Renewable Energy Sources for his work on sustainable power systems and specifically the control and optimization of distributed energy resources in future smart grids. The winner of the prize in Nanotechnology was Niranjan Srinivas  for designing and building a system of DNA machines that, in bulk, implement an oscillator. Niranjan's advisor was Eric Winfree.

Tags: EE honors MCE CMS Nadia Lapusta Steven Low Demetriades - Tsafka - Kokkalis Alborz Mahdavi David Tirrell Srivatsan Hulikal Lingwen Gan Niranjan Srinivas Eric Winfree

Faulty Behavior

01-09-13

Nadia Lapusta, Professor of Mechanical Engineering and Geophysics, and colleagues have created new earthquake fault models showing that “stable” zones may contribute to the generation of massive earthquakes. "Lapusta and Noda's realistic earthquake fault models are critical to our understanding of earthquakes—knowledge that is essential to reducing the potential catastrophic consequences of seismic hazards," says Chair Ares Rosakis. "This work beautifully illustrates the way that fundamental, interdisciplinary research in the mechanics of seismology at Caltech is having a positive impact on society." [Caltech Release]

Tags: research highlights MCE Nadia Lapusta

Greater Insight into Earthquake Cycles

05-10-12

Nadia Lapusta, Professor of Mechanical Engineering and Geophysics, and colleagues have developed the first computer model of an earthquake-producing fault segment that reproduces, in a single physical framework, the available observations of both the fault's seismic (fast) and aseismic (slow) behavior. "Earthquake science is on the verge of building models that are based on the actual response of the rock materials as measured in the lab—models that can be tailored to reproduce a broad range of available observations for a given region," says Lapusta. "This implies we are getting closer to understanding the physical laws that govern how earthquakes nucleate, propagate, and arrest." [Caltech Press Release]

Tags: research highlights MCE Nadia Lapusta

Aseismic Slip as a Barrier to Earthquake Propagation

05-06-10

Tectonics Observatory researchers including Nadia Lapusta, Associate Professor of Mechanical Engineering and Geophysics, have explored the effects of aseismic slip in the aftermath of the 2007 Peru earthquake. "This large area of aseismic slip is good news," says Jean-Philippe Avouac, Director of the Tectonics Observatory and Professor of Geology. "It lowers the seismic hazard in that region, and allows us to be a little bit predictive. We cannot tell you when there will be an earthquake, but we can tell you where there is stress buildup, and where there is no stress buildup. Where there is no stress buildup, there will be no seismic rupture. That is where the earthquakes are going to stop." [Caltech Press Release]

Tags: research highlights MCE Nadia Lapusta Jean-Philippe Avouac