Collaborative Research: Characterizing fault zones at Kilauea and Mauna Loa volcanoes by large-scale mapping of earthquake stress drops and high precision relocations

合作研究：通过大规模地震应力降绘图和高精度重新定位来表征基拉韦厄火山和莫纳罗亚火山的断层带

• 批准号: 1045042
• 负责人: Cecily Wolfe
• 金额: $ 6.92万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-02-01 至 2015-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1045042&HistoricalAwards=false
• 关键词: Collaborative; Research; Characterizing; fault; zones

Hawaii is one of the most active volcanic regions in the world, with the long-lived Pu'u' O'o-Kupaianaha eruption of Kilauea continuing since 1983. The magmatic activity is accompanied by high rates of earthquake activity and Hawaii has great value as a natural laboratory for studying the interactions between magmatic and tectonic processes. The seismic network operated by the U.S. Geological Survey (USGS) Hawaii Volcano Observatory (HVO) records thousands of events every year and since 1986 a substantial database of earthquake waveforms has accumulated. This project will involve analyses of these data to improve earthquake location accuracy and to resolve more details of earthquake source processes, such as the amount of stress that is relieved during faulting. The PIs will adopt a number of new methods that have been used successfully in the analysis of southern California seismicity and apply them to the Hawaiian dataset. The results from this study are expected to yield a sharper view of fault zone characteristics as well as generate a public database of information suitable for other researchers in their work at Hawaii.This project is a collaboration among U.C. San Diego, the University of Hawaii, and USGS HVO to apply a variety of newly developed seismic techniques to analyze waveforms from ~200,000 earthquakes recorded by the HVO seismic network in one of the most active volcanic regions in the world. These methods promise to greatly improve event location accuracy and to provide robust estimates of the patterns of earthquake stress drops, results that will help characterize fault-zone structures at Hawaii and help resolve the relationships between seismicity, volcanic activity, and strain transients. Our results will address the following questions: (1) Relocated microearthquakes in Hawaii will likely align along resolvable fault and/or conduit structures: what do these structures reveal about the tectonic and volcanic processes? (2) Are there repeating earthquakes with nearly identical waveforms, and can they be used to resolve temporal variations in seismic velocity associated with tectonic and volcanic activity? (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) Are earthquakes at Hawaii self-similar, such that average stress drop is constant with event size and large earthquakes are simply scaled up versions of smaller earthquakes? (5) What is the space/time evolution of seismicity at Hawaii? Are there consistent temporal variations in seismicity and earthquake properties related to ongoing volcanic activity and strain transients? How much of the observed clustering in the earthquake catalog can be explained by mainshock/aftershock triggering models (e.g., ETAS) and how much reflects possible physical triggers such as fluid migration or slow slip?

夏威夷是世界上最活跃的火山区之一，自1983年以来，长期以来一直持续的pu'u'o'o'o'o'o'o-kupaianaha爆发继续进行。岩浆活动伴随着高地震活动，夏威夷具有很大的价值作为研究磁相互作用的自然实验室，用于研究磁相互作用。 美国地质调查局（USGS）夏威夷火山天文台（HVO）经营的地震网络每年都记录了数千起事件，自1986年以来，地震波形的大量数据库已积累。 该项目将涉及对这些数据的分析，以提高地震位置的准确性并解决地震源过程的更多细节，例如在断层期间减轻的压力量。 PI将采用多种新方法，这些方法已成功地用于分析南加州地震性，并将其应用于夏威夷数据集。这项研究的结果预计将对断层区特征产生更清晰的视野，并在夏威夷的工作中生成适合其他研究人员的信息数据库。该项目是U.C.的合作。圣地亚哥，夏威夷大学和USGS HVO应用各种新开发的地震技术来分析HVO地震网络在世界上最活跃的火山区之一记录的200,000次地震的波形。 这些方法有望极大地提高事件位置的准确性，并提供对地震应力下降模式的强大估计，结果将有助于表征夏威夷的断层区结构，并有助于解决地震性，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）夏威夷的重新定位的微夸克可能会沿着可分离的断层和/或导管结构保持一致：这些结构揭示了有关构造和火山过程的什么？ （2）是否有几乎相同波形的重复地震，并且可以用来解决与构造和火山活动相关的地震速度的时间变化吗？ （3）与其他地区相比，夏威夷地震的压力下降如何？ 地震应力下降的变化是否可用于表征应力场异质性并鉴定应力浓度的区域？ （4）夏威夷的地震是自相似的，这样平均应力下降是恒定的，而事件大小和大地震只是缩小较小地震的版本？ （5）夏威夷地震性的空间/时间演变是什么？ 与持续的火山活动和应变瞬变有关的地震性和地震特性的时间变化是否一致？ 地震目录中观察到的聚类中有多少可以通过主震/余震触发模型（例如ETA）来解释，以及多少反映可能的物理触发器，例如流体迁移或慢速滑移？