Collaborative Research: Time Dependence of Seismic Parameters in Hawaii

夏威夷是世界上地震最活跃的地区之一。在过去的几十年里，它一直被用作研究地震和岩浆作用之间相互作用的天然实验室。美国地质调查局(USGS)夏威夷火山观测站(HVO)拥有广泛的仪器网络，可以实时调查夏威夷岛上正在进行的活动。然而，对地震参数的时间变化的关注要少得多。这些变化在量化活动和可能预测重大破坏性事件方面具有相当大的潜力。在这里，研究人员计算了夏威夷岛上过去33年记录的所有事件的地震参数。他们分析了它们的时间相关性，并检查了重大事件前后的长期变化和短期变化。一个目标是评估过去事件所解释的地壳应力变化在多大程度上可以预测未来的大事件。该团队还调查了活动是否存在长期演变。该项目为几名研究生和本科生提供支持和培训。它的结果对预测夏威夷岛上的地震和火山事件有直接的影响。这项为期三年的奖项是由NSF极端事件预测和抵御极端事件(PREEVENTS)计划共同资助的。该项目旨在完成对地震参数时间变化的全面搜索，并对地震和岩浆作用之间的相互作用获得新的见解。所研究的参数包括地震活动性、b值、断层面解、尾波Q、速度和各向异性结构以及近源波速比。这项工作利用了美国地质勘探局高压地震台记录的数字地震数据。它利用了先前研究提供的可用的三维地震速度和衰减模型、地震重新定位和震源解决方案。结果量化了岩浆(喷发和侵入)和非岩浆(地震和慢滑)事件前后地震参数的潜在变化。他们还评估了过去33年来潜在的长期变化。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.