Studies of Unusual Earthquakes: Volcanos and Landslides

该项目涉及对异常震源的调查，特别侧重于与火山和滑坡有关的缓慢地震。它建立在对全球地震台网记录的实时和存档地震数据进行长周期事件检测算法系统应用的结果和发现的基础上。自1991年以来，每年都有超过100次5级或5级以上的地震，这些地震没有在其他目录中报告，已经使用这种算法检测和定位。这些地震中有许多是缓慢的，其中大部分与火山和山体滑坡有关。该项目的第一个目标是将火山和滑坡地震与其他仅通过长周期检测算法识别的地震区分开来。第二个目标是将那些发生在火山地区的地震与喷发活动以及岩浆管道系统的几何形状和行为的变化联系起来。特别是，该项目将包括对与上世纪两个最大的玄武岩火山火山口崩塌有关的不寻常地震的详细比较研究，这两个火山分别是费尔南迪纳（加拉帕戈斯群岛）和三宅岛（日本）。第三个目标是调查与大型滑坡事件有关的异常地震。一个最近发展的方法，确定滑动体的轨迹在滑坡期间直接从辐射地震波将被完善和改进，并应用于几个已知和推断的滑坡事件，以估计动态滑坡参数。该项目将改进震源的特征和识别，并将有助于阐明火山和滑坡地震的现象。火山调查将为活火山内部的应力和变形模式，以及火山口崩塌的机制及其与岩浆运输和管道的关系提供新的限制。滑坡调查将有助于更好地表征滑坡源的地震辐射，并将为滑坡的关键参数（如质量、跳动和有效摩擦系数）提供新的约束。为这些研究开发的地震分析方法将有助于提高对代表重要地质灾害类别的火山和滑坡的监测能力。

The project involves the investigation of anomalous seismic sources with a specific focus on slow earthquakes associated with volcanos and landslides. It builds on results and discoveries that have come from the systematic application of a long-period event detection algorithm to real-time and archive seismic data recorded on the Global Seismographic Network. For each year since 1991, more than 100 earthquakes of magnitude 5 or greater that are not reported in other catalogs have been detected and located using this algorithm. Many of these earthquakes are slow, and a large number of them have been associated with volcanos and landslides. The first goal of the project is to discriminate volcano and landslide earthquakes from other earthquakes that have been identified only by the long-period detection algorithm. The second goal is to relate those earthquakes that occur in volcanic regions to eruptive activity and changes in the geometry and behavior of magmatic plumbing systems. In particular, the project will involve a detailed comparative study of unusual earthquakes associated with the two greatest caldera collapses of basaltic volcanos over the last century, Fernandina (Galapagos Islands) and Miyakejima (Japan). The third goal is to investigate anomalous earthquakes associated with large landslide events. A recently developed methodology for determining the trajectory of the sliding mass during a landslide directly from the radiated seismic waves will be refined and improved and applied to several known and inferred landslide events in order to estimate dynamic landslide parameters.The project will lead to an improved characterization and discrimination of earthquake sources, and will help clarify the phenomenology of volcano and landslide earthquakes. The volcano investigations will provide new constraints on stress and deformation patterns within active volcanoes, as well as on the mechanics of caldera collapse and its relationship to magmatic transport and plumbing. The landslide investigations will lead to better characterization of the seismic radiation from landslide sources, and will provide new constraints on key landslide parameters, such as mass, runout, and effective coefficient of friction. The seismological analysis methods developed for these studies will contribute to improved monitoring capabilities for volcanos and landslides, which represent important classes of geohazards.