Characterizing fault zones at Kilauea & Mauna Loa volcanoes by large-scale mapping of earthquake stress drops and focal mechanisms

从地幔内部到地表的地震源的分析和解释对于理解火山是如何工作的起着关键作用。夏威夷岛是地球上构造、火山和地震最活跃的地区之一。美国地质勘探局夏威夷火山观测站(HVO)运行的地震台网自1986年以来已经记录了超过26万次地震，但这一丰富的数据集尚未得到充分利用。该项目支持HVO、加州大学圣巴巴拉分校和加州大学圣地亚哥分校之间的合作，应用许多新的大数据集处理方法，以更多地了解夏威夷的地震活动及其与断层和火山的关系。它还通过为研究生提供资助来支持加州大学圣巴巴拉分校的教育项目。这项研究的结果有望对断裂带特征产生更清晰和更全面的看法，并产生关于地震活动特征的高分辨率信息的公共数据库，适用于其他研究人员在夏威夷地质、构造和火山作用的研究。这项研究将改进对夏威夷地震活动和构造的描述，这将提高我们监测和表征火山和地震危险的能力。通过对HVO记录的地震活动进行系统和全面的分析，这项工作将提高地震定位精度，提供对地震应力降模式的稳健估计，并计算出更可靠的夏威夷震源机制。综合这些结果将更好地描述基拉韦厄火山和毛纳罗亚火山及其周围的地壳和地幔断裂带以及岩浆管道，并将有助于解决地震活动、火山活动和应变瞬变之间的关系。我们的结果将解决以下问题：(1)夏威夷重新定位的微震沿着可分解的断层和导管构造排列？这些构造揭示了构造和火山过程的什么？(2)最近在夏威夷发现的地震活动环的起源是什么？(3)夏威夷地震的应力降与其他地区相比如何？地震应力降是否有变化，可以用来表征应力场的不均一性和确定应力集中区？(4)夏威夷小震的震源机制能否得到改善，它们揭示了断层过程和应力状态的什么？(5)波形几乎相同的重复地震能否用来解决与构造和火山活动有关的地震速度的时间变化？(6)基拉韦厄火山的长周期(Lp，0.5-5赫兹)地震活动的特征与岩浆和岩浆供应系统内的应力重新分布有何关系？

The analysis and interpretation of seismic sources from within Earth's mantle up to the surface plays a key role in understanding how volcanoes work. Hawaii Island is one of the most tectonically, volcanically, and seismically active regions on Earth. The USGS Hawaiian Volcano Observatory (HVO) operates a seismic network that has recorded over 260,000 earthquakes since 1986, but this rich dataset has not been fully exploited. This project supports collaboration between HVO, U.C. Santa Barbara, and U.C. San Diego to apply a number of new large-dataset processing methods to learn more about seismic activity on Hawaii and its relationship to faults and volcanoes. It also supports the educational program at U.C. Santa Barbara by providing funds for graduate student support. The results from this study are expected to yield a sharper and more comprehensive view of fault zone characteristics as well as generate public databases of high-resolution information on seismicity characteristics, suitable for other researchers in their studies of Hawaiian geology, tectonics, and volcanism. This research will lead to improved descriptions of seismicity and tectonics for Hawaii, which will improve our ability to monitor and characterize volcanic and earthquake hazards.By performing systematic and comprehensive analyses of seismicity recorded by HVO, this work will improve earthquake location precision, provide robust estimates of the patterns of earthquake stress drops, and compute more reliable earthquake focal mechanisms on Hawaii. Integrating these results will better characterize crustal and mantle fault zones and magma conduits in and around Kilauea and Mauna Loa volcanoes, and will help to resolve the relationships between seismicity, volcanic activity, and strain transients. Our results will address the following questions: (1) Relocated microearthquakes in Hawaii align along resolvable fault and conduit structures?what do these structures reveal about tectonic and volcanic processes? (2) What is the origin of recently discovered seismicity rings in Hawaii? (3) How do the stress drops of Hawaiian earthquakes compare to other regions? Are there variations in earthquake stress drops that can be used to characterize stress field heterogeneity and identify regions of stress concentration? (4) Can focal mechanisms be improved for small earthquakes in Hawaii and what do they reveal about the faulting process and stress state? (5) Can repeating earthquakes with nearly identical waveforms be used to resolve temporal variations in seismic velocity associated with tectonic and volcanic activity? (6) How do the characteristics of long-period (LP, 0.5-5 Hz) seismicity at Kilauea volcano relate to redistributions of magma and stress within its magma supply system?