Workshop Support: An EarthScope Institute on the Spectrum of Fault Slip Behaviors

最近的研究使用了地球观测设备以及其他国内和国际来源的数据，表明构造断层表现出广泛的滑动行为，从蠕变到地震，包括一些10年前还不为人知的现象。瞬态断层滑动（TFS）包括缓慢和无声的地震、间歇性震颤和滑动、蠕变事件、低频地震、海啸地震和震后断层余震。从地震蠕变到地震，似乎有一个连续的滑动模式谱。这些观察结果挑战了过去40年来存在的脆性断层的标准观点，即摩擦滑动只发生在两种模式中的一种：粘滑或稳定蠕变。尽管现代摩擦本构定律预测断层滑动将表现出一系列瞬态行为，但人们对其潜在过程知之甚少，对关键本构参数的约束也很差。此外，现有的摩擦模型需要特殊条件才能产生自持续的慢滑模态，并且震颤等现象没有得到很好的描述，这可能表明模型中需要额外的过程。2010年10月11日至14日，约100名研究人员（包括博士后、学生和教师）在俄勒冈州波特兰举行了一场关于TSF和相关现象的研讨会。讲习班的主要目标是：1)提供智力领导，培养对TFS的潜在机制和物理过程的批判性思维；2)促进广泛的、基于社区的对TFS的理解的兴趣；3)在观测、理论和实验室研究项目之间建立合作关系；4)讨论识别可能承载瞬态应变释放的新断层滑动现象和新构造环境的新方法；5)发起一个持续的基于网络的虚拟“研究所”，专门研究TFS。研讨会和虚拟研究所促进了从大地测量学和地震学到岩石力学、岩石学、水文地质学、构造学和地球动力学等学科的教育和交流，并为年轻研究人员提供了一个扩大他们的理解和参与一个备受瞩目的问题的研究的机会。重点研究TFS应阐明缓慢和瞬态滑动在地震触发和地震危险性评估中的潜在作用。

Recent studies using data from the EarthScope Facility as well as other national and international sources show that tectonic faults exhibit a broad spectrum of slip behaviors ranging from creep to earthquakes, including several phenomena that were unknown as recently as 10 years ago. Transient fault slip (TFS) includes slow and silent earthquakes, episodic tremor and slip, creep events, low frequency earthquakes, tsunamigenic earthquakes, and postseismic fault afterslip. There appears to be a continuous spectrum of slip modes ranging from aseismic creep to earthquakes. These observations challenge the standard view of brittle faulting that has existed for the past 40 years, in which frictional slip occurs in one of only two modes: stick-slip or stable creep. Although modern friction constitutive laws predict that fault slip will exhibit a range of transient behaviors, the underlying processes are poorly understood and key constitutive parameters are poorly constrained. Moreover, existing frictional models require special conditions to produce self-sustained modes of slow slip, and phenomena such as tremor are not well described, which may indicate that additional processes are needed in the models. A workshop on TSF and related phenomena for ~100 researchers, including post-docs, students and faculty, is being held on October 11-14, 2010, in Portland OR. The primary goals of the workshop are to: 1) provide intellectual leadership and foster critical thinking about the underlying mechanisms and physical processes responsible for TFS, 2) promote broad, community-based interest in understanding TFS, 3) seed collaborations between observational, theoretical and laboratory-based research programs, 4) discuss novel approaches for identifying new fault slip phenomena and new tectonic settings that may host transient strain release, and 5) initiate a continuing web-based virtual "institute" dedicated to TFS.The workshop and virtual institute foster education and communication across disciplines ranging from geodesy and seismology to rock mechanics, petrology, hydrogeology, tectonics, and geodynamics and provide an opportunity for young researchers to broaden their understanding and become involved in research on a high-profile problem. Focused study of TFS should elucidate the potential role of slow and transient slip on earthquake triggering and seismic hazard assessment.