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.

地震代表了弹性能量的突然释放，该弹性能量储存在与构造断层相邻的岩石中，驱动灾难性的失败。 在正常的（快速）地震中，破裂区以每秒几公里的速度扩张，断层滑移速率达到每秒1至10米。 但是，构造断层在慢速地震中，破裂持续时间或数月或更长时间，而断层滑移速度的小分数每秒或更少一英寸。 最近的工作表明，构造断层在滑移模式中失败，包括缓慢地震，正常（快速）地震和许多其他形式的滑移。 这些缓慢的滑动模式可以将应力转移到快速地震区，并可能触发正常地震。但是，我们对缓慢地震的机制知之甚少。 这项研究工作将解决以下问题：什么决定了缓慢地震的破裂速度？这项工作的一个核心要素是对重复，慢速滑移事件的实验室研究，并连续测量声发射，弹性波速度和振幅以及断层区摩擦行为。 要测试的假设包括：1）慢速滑移失败代表一系列材料和2）的过度捕捉正常（快速）滑动和2）相同的断层区可以容纳缓慢而快速的滑动行为。Slow地震是一种瞬态断层滑移，可能会加载故障区域的地震部分和abet损坏地震。缓慢地震的起源和相关形式的瞬态断层滑移的理解很少。该项目将采用一种系统的调查方法：1）慢速滑移的基本过程，重点是摩擦机制和连续耦合，可以解释自然界中断层滑移行为的频谱，2）实验室样品的微结构研究，以评估剪切定位和剪切分布的特定（快速）和慢速（快速）和慢速（快速粘贴）的特性和慢速分布的特性和3次效率，并且是慢速（快速粘贴和3）的效率（3）效率（3）。 失败。 拟议的研究将扩大摩擦滑滑和正常（快速）地震之间的类比，以包括缓慢的滑移事件。 结果将提供有关缓慢地震和其他形式的准动态断层滑动的洞察力。获得的所有数据和结果将在同行评审的期刊上发布，并通过公共网站提供。