ASPERITY: Aseismic SliP and Earthquake Ruptures: Interrogating Transitions in rheologY

粗糙度：抗震滑移和地震破裂：探讨流变学的转变

• 批准号: EP/Y024672/1
• 负责人: Ake Fagereng
• 金额: $ 258.52万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FY024672%2F1
• 关键词: ASPERITY; Aseismic; SliP; Earthquake; Ruptures

Where and why tectonic faults produce earthquakes or slip aseismically is a critical Earth Science question that remains unanswered, despite representing prerequisite knowledge for probabilistic earthquake forecasting. It is known that earthquakes are typically generated by frictional failure, which initiates where stress is high or strength is low relative to bulk fault zone strength. Fault zones therefore have earthquake-generating patches ('asperities') surrounded by areas likely to creep aseismically. This varied behaviour has been ascribed to variation in fault zone properties. Current models for the spectrum of fault slip styles, however, are based on laboratory-scale observations, typically in single rock types, described by sophisticated empirical constitutive laws. These laws lack insights into underlying physical properties and interaction of multiple materials over km-scales and multiple earthquake cycles. This is a critical knowledge gap that prevents development of realistic earthquake models - ASPERITY will bridge this gap. ASPERITY proposes a generalised model for natural faults where 'asperities' are defined as areas where, over an earthquake cycle, the amount of co-seismic slip exceeds the magnitude of aseismic creep. This model raises the specific hypothesis that interaction between asperities and surrounding fault rock determines fault slip style. To test this hypothesis, we will collect quantitative geological evidence from the rock record, link natural and laboratory deformation microstructures, and develop numerical models to bridge the scale to plate boundary faults. This will lead to specific scenarios that forecast where earthquakes, creep, and slow earthquakes occur in terms of variables that can be quantified in nature. This outcome is a step-change from empirical to physical understanding of where and why some tectonic faults move in episodic, potentially damaging earthquakes, while others creep silently and pseudo-continuously.

尽管代表了概率地震预测的先决条件，但在哪里以及为什么在何处以及为什么在地震或无性地上产生地震或裂开是一个尚未得到解答的关键地球科学问题。众所周知，地震通常是由摩擦故障产生的，摩擦力失败会引起压力高或强度相对于散装断层区强度低的强度。因此，断层区具有产生地震的斑块（“ sperities”），周围有可能在狂热上爬行的区域。这种多样化的行为已归因于断层区特性的变化。然而，当前的故障滑移样式的模型基于实验室规模的观测值，通常以单岩类型为中，由复杂的经验本构定律描述。这些法律缺乏对KM尺度和多种地震周期多种材料的潜在物理特性和相互作用的见解。这是一个关键的知识差距，阻止了现实的地震模型的发展 - 阿斯伯特将弥合这一差距。 Asberity提出了一个自然断层的广义模型，在该模型中，“浅层”被定义为地震周期中的区域，共抗性滑移的量超过了Aseasmist蠕变的幅度。该模型提出了一个具体的假设，即浅层与周围故障岩石之间的相互作用决定故障滑移样式。为了检验这一假设，我们将从岩石记录，自然和实验室变形微观结构中收集定量地质证据，并开发数值模型以将尺度桥接到板边界故障。这将导致特定的情况，这些方案预测地震，蠕变和慢速地震发生在自然界中可以量化的变量方面发生。这种结果是从经验到对某些构造断层在何处以及为什么在情节性的，潜在破坏性地震中移动的阶梯变化，而其他人则无声地爬行和伪延迟。