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

构造断层在哪里以及为什么产生地震或地震滑动是一个关键的地球科学问题，仍然没有答案，尽管代表了概率地震预测的先决条件知识。众所周知，地震通常是由摩擦破坏产生的，摩擦破坏发生在应力高或强度相对于整体断层带强度低的地方。因此，断层带具有地震生成斑块（“凹凸不平”），周围是可能发生地震蠕动的区域。这种不同的行为已被归因于断层带性质的变化。然而，目前的断层滑动类型谱模型是基于实验室规模的观测，通常是在单一的岩石类型，由复杂的经验本构关系描述。这些定律缺乏对公里尺度和多个地震周期内多种材料的基本物理性质和相互作用的了解。这是一个关键的知识差距，阻碍了现实地震模型的发展- ASPERITY将弥合这一差距。粗糙度提出了一个广义模型的天然断层，其中的“粗糙度”被定义为地区，在地震周期，同震滑动量超过的大小的抗震蠕变。该模型提出了一个具体的假设，即粗糙体与断层围岩的相互作用决定了断层的滑动方式。为了验证这一假设，我们将从岩石记录中收集定量地质证据，将自然和实验室变形微观结构联系起来，并开发数值模型，以弥合规模与板块边界断层。这将导致特定的场景，预测地震，蠕变和慢地震发生的变量，可以量化的性质。这一结果是从经验到物理理解的一个步骤，即一些构造断层在哪里以及为什么会在间歇性的、可能具有破坏性的地震中移动，而另一些断层则无声地、伪连续地蠕动。

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.