The Spectrum of Fault Slip Behaviors and the Mechanics of Slow Earthquakes

断层滑动行为谱和慢地震机制

• 批准号: 1520760
• 负责人: Chris Marone
• 金额: $ 39.5万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1520760&HistoricalAwards=false
• 关键词: Spectrum; Fault; Slip; Behaviors; Mechanics

Earthquakes represent a sudden release of elastic energy that is stored in the rocks adjacent to tectonic faults, driving catastrophic failure. In normal (fast) earthquakes the rupture zone expands at a few kilometers per second, and fault slip rates reach 1 to 10 meters per second. However, tectonic faults also fail in slow earthquakes with rupture durations of months or more and fault slip speeds of a of small fraction of an inch per second or less. Recent work shows that tectonic faults fail in spectrum of slip modes that includes slow earthquakes, normal (fast) earthquake, and many other forms of slip. These slow modes of slip can transfer stress to the fast earthquake zone and potentially trigger damaging, normal earthquakes. However, we know very little about the mechanics of slow earthquakes. This research effort will address questions such as: what determines the rupture speed of slow earthquakes? A central element of this work is carefully conducted laboratory studies of repetitive, slow stick-slip events with continuous measurement of acoustic emission, elastic wave speed and amplitude, and fault zone friction behavior. Hypotheses to be tested include: 1) does slow slip failure represents prematurely arrested normal (fast) slip for a range of materials and 2) can the same fault zone can host slow and fast slip behaviors.Slow earthquakes are one form of transient fault slip that may load seismogenic portions of fault zones and abet damaging earthquakes. The origin of slow earthquakes and related forms of transient fault slip is poorly understood. The project will take a systematic approach to investigate: 1) the underlying processes of slow slip, with focus on the frictional mechanisms and continuum coupling that may explain the spectrum of fault slip behaviors in nature, 2) microstructural studies of the laboratory samples to assess how shear localization and strain distribution compare between normal (fast) and slow stick-slip, and 3) acoustic measurement of fault zone elastic properties, with particular focus on precursors to failure. The proposed study will extend the analogy between frictional stick-slip and normal (fast) earthquakes to include slow slip events. The results will provide insight on the mechanics of slow earthquakes and other forms of quasi-dynamic fault slip. All data and results obtained will be published in peer-reviewed journals and made available via public websites.

Earthquakes represent a sudden release of elastic energy that is stored in the rocks adjacent to tectonic faults, driving catastrophic failure. In normal (fast) earthquakes the rupture zone expands at a few kilometers per second, and fault slip rates reach 1 to 10 meters per second. 然而，构造断层也会在破裂持续时间长达数月或更长、断层滑动速度为每秒几分之一英寸或更小的慢地震中失效。 最近的研究表明，构造断层在滑动模式谱中失效，包括慢地震、正常（快）地震和许多其他形式的滑动。 这些缓慢的滑动模式可以将应力转移到快速地震区，并可能引发破坏性的正常地震。 However, we know very little about the mechanics of slow earthquakes. 这项研究工作将解决诸如以下问题：什么决定了慢地震的破裂速度？这项工作的核心要素是通过连续测量声发射、弹性波速度和振幅以及断层带摩擦行为，对重复的缓慢粘滑事件进行仔细的实验​​室研究。 要测试的假设包括：1) 慢滑移失效是否代表一系列材料的正常（快速）滑移过早停止，2) 同一断层带是否可以发生慢滑移和快滑移行为。慢地震是瞬态断层滑移的一种形式，可能会加载断层带的发震部分并助长破坏性地震。人们对慢地震的起源和瞬态断层滑动的相关形式知之甚少。该项目将采用系统方法来研究：1）慢滑动的基本过程，重点关注可以解释自然界中断层滑动行为谱的摩擦机制和连续介质耦合，2）实验室样本的微观结构研究，以评估正常（快）粘滑和慢粘滑之间剪切定位和应变分布的比较，以及3）断层带弹性特性的声学测量，特别关注断层带弹性特性的声学测量，特别关注 失败。 拟议的研究将扩展摩擦粘滑和正常（快）地震之间的类比，以包括慢滑事件。 The results will provide insight on the mechanics of slow earthquakes and other forms of quasi-dynamic fault slip.获得的所有数据和结果将发表在同行评审的期刊上，并通过公共网站提供。