Collaborative Research: Origin of hydrologic responses to earthquakes: constraints from New Zealand Taiwan Chile and USA

PROJECT SUMMARY Overview: Page A The origin of hydrologic responses to earthquakes has been the subject of controversy, in large part because there are many models to explain observations and few measurements suitable for distinguishing between hypotheses. We will study responses to earthquakes in New Zealand, Chile, Taiwan, and California to test competing hypotheses by 1) compiling observations, 2) collecting new measurements, and 3) developing analytical and numerical models to interpret the hydrological and related geodetic data. We will address the following questions: a) Does the excess discharge in streams originate from the shallow or deep subsurface? b) How do the response of deep and groundwater systems differ? c) Are there different and understandable responses of fracture-dominated rock and unconsolidated materials? d) Are there permanent changes in properties of the subsurface such as permeability? e) Are static or dynamic stresses more important for explaining the observed changes? Intellectual Merit : Earthquakes generate hydrological responses, such as increases in stream flow and changes in the water level in wells. Such hydrologic responses are important because they provide unique insight into the coupling of hydrologic and tectonic processes at spatial and temporal scales that are otherwise difficult to study. Broader Impacts : This project offers an interdisciplinary training opportunity that integrates geophysics and hydrology, and combines modeling and field studies. The proposed work is an international collaboration with colleagues in Taiwan, Germany and New Zealand. We will integrate the proposed research with courses taught at UC Berkeley, including freshman seminars, undergraduate-level geodynamics, and graduate level classes. The study of earthquake-induced hydrologic changes has implications for water resources and engineering, including assessing the role of earthquakes in damaging aquifers, affecting underground repositories, and changing water supplies.