Collaborative Research: Time Dependence of Seismic Parameters in Hawaii

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Hawaii is one of the most seismically active regions in the world. For the past few decades, it has been used as a natural laboratory for studying the interactions between seismic and magmatic processes. The U.S. Geological Survey (USGS) Hawaiian Volcano Observatory (HVO) has an extensive network of instruments to investigate in real-time the ongoing activity on the island of Hawaii. Yet, much less attention has been paid to seismic-parameter temporal variations. These variations have considerable potential for quantifying the activity and possibly forecasting major destructive events. Here, the researchers calculate seismic parameters for all events in the Hawaii island recorded over the past 33 years. They analyze their time dependence and examine both the long-term variations and the short-term changes before and after significant events. One goal is to evaluate to what extend crustal stress changes explained by past events are predictive of future large events. The team also investigates whether there is a long-term evolution in activity. This project provides support and training for several graduate and undergraduate students. Its outcomes have direct implications for forecasting seismic and volcanic events in Hawaii island. The three-year award was co-funded by NSF Prediction of and Resilience against Extreme Events (PREEVENTS) program.The project aims to complete a comprehensive search for temporal variations in seismic parameters and gain new insights into the interactions between seismic and magmatic processes. The investigated parameters include seismicity rate, b-value, fault plane solutions, coda Q, velocity and anisotropy structure, and near-source Vp/Vs ratios. The work exploits digital seismic data recorded by the USGS HVO seismic stations. It leverages on available 3-D seismic velocity and attenuation models, earthquake relocations, and focal solutions provided by prior studies. Results quantify potential variations in seismic parameters before and after magmatic (eruptions and intrusions) and non-magmatic (earthquakes and slow-slip) events. They also evaluate potential long-lasting changes over the past 33 years.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.