Biography
Dr. Emily Brodsky is a distinguished professor of Earth and Planetary Sciences at the University of California, Santa Cruz. As a leading earthquake physicist, Dr. Brodsky investigates the fundamental mechanics underlying earthquakes, exploring critical questions about earthquake triggering processes and the forces at work within fault zones during seismic events.
Dr. Brodsky's research spans multiple geoscience disciplines, including seismology, hydrogeology, structural geology, and rock mechanics. Her innovative work has provided important insights into human-induced earthquakes related to hydraulic fracturing, wastewater disposal, and geothermal energy production.
Following the catastrophic 2011 Tohoku earthquake in Japan, Dr. Brodsky played a key role in organizing and leading a major international expedition to study the fault. Her research has been featured in prominent media outlets such as the BBC, NPR, the New York Times, and Time magazine.
Dr. Brodsky received her bachelor's degree from Harvard University and her Ph.D. in geophysics from the California Institute of Technology. Her numerous accolades include the 2022 Nemmers Award in Earth Science, the 2021 Price Medal from the Royal Astronomical Society, and the 2008 James Macelwane Medal from the American Geophysical Union. In 2023, she was elected to the National Academy of Sciences.
A dedicated mentor, Dr. Brodsky has guided numerous postdoctoral scientists, graduate students, and undergraduate researchers throughout her career. She has published over 130 peer-reviewed articles and delivered over 150 invited lectures worldwide. Brodsky currently chairs SZ4D, a coordinated research initiative focused on subduction zones.
Within her groundbreaking research and commitment to scientific advancement, Dr. Emily Brodsky continues to shape our understanding of earthquake physics and contribute to mitigating seismic hazards.
Public Lecture: The Earthquake Problem
Earthquake prediction has simultaneously remained both the central, unsolved problem of our field and the most pertinent issue in the public's imagination. Here we will discuss what we do and do not know about when earthquakes will happen. We will look at what we understand about the basic mechanics of faults and how drilling into faults has transformed our understanding of how earthquakes happen. We will also explore how the machine learning revolution is powering a transformation in forecasting aftershocks. Finally, we will look forward to the kind of instrumentation and approaches that are most promising for the next big advances.
Technical Lecture: The variability of stress and what to do about it
Abstract: Stress is not uniform in the Earth. Even over relatively small volumes, pore pressure fluctuations, fault complexity, and lithological variations conspire to create a stress state that is difficult to describe with a single quantity. Given that any quantification of failure requires knowledge of the stress state, the lack of uniformity is a major problem limiting our knowledge of the initiation conditions of earthquakes, volcanic eruptions, landslides or any other geohazard that involves catastrophic collapse.
A route forward is to measure distribution of stresses in the Earth, rather than single values. Dynamic triggering and induced seismicity both provide information on the distribution of stresses required for failure. Fault roughness may also reflect the distribution of strength, which in turn affects in situ stresses. The probability of propagation along a fault rupture provides further information. Observations of all of these distributions are surprisingly robust and suggest some degree of self-organization in the Earth.
Heterogeneous stress results in qualitatively different behavior than uniform stress. Laboratory analog models with naturally evolving stress heterogeneity produce slip events with normal-stress independent of stress drops as observed in the Earth. Transient, spatially variable locking also emerges naturally in laboratory experiments if heterogeneity is allowed to occur. Stress heterogeneity also results in qualitative distinct features in nature. For instance, tremor synchronization in space seems to be limited by the activity of small, nearby crustal and intraslab earthquakes. This observation can be explained by a competition between the self-synchronization of fault segments and perturbation by regional earthquakes, which create a more heterogeneous field. The results imply previously unrecognized interactions across subduction systems, in which earthquake activity far from the fault influences whether it breaks in small or large segments.
In sum, the variability of the stress field is an inevitable, and in fact, tractable aspect of tectonic systems with non-trivial consequences for geohazards.