A study of induced seismicity: From micro- to macro-scale

在过去的十年里，北美的地震数量急剧增加，其中许多地震大到足以让人类在地表感觉到，在某些情况下已经造成了破坏。这些事件被称为诱发地震活动，是由沿断层的流体诱发应力变化引起的断层滑动造成的。观测到的诱发地震活动性增加主要与废水处理有关；然而，国内外也将诱发地震活动与水力压裂和增强型地热系统（EGS）联系起来。相反，由于应对全球气候变化仍然是21世纪的一个核心政治问题，寻找合适的可再生能源替代品的竞赛已经开始，而EGS就是其中之一。因此，注入引起的地震活动及其对人口和环境的影响将继续成为未来几年的中心问题。为了更好地规范这些行业，最大限度地减少对社会和环境的负面影响，需要进行基础研究，以更好地了解导致诱发地震的关键过程以及它们如何在自然环境中展开。这是拟议项目的首要目标。这项研究计划的长期目标是通过新的实验室实验、数据分析技术和数值模拟的使用和发展，提高我们对流体诱发地震活动的理解，并缩小实验室实验和地球物理观测之间的差距。在自然断层和锯切断层上进行一系列新颖的流体注入实验，研究断层的再激活过程，收集声发射（AE）、超声速度、断层位移、应力、流体压力和注入速度的测量数据。将对声发射传感器进行校准，以便与现场地震活动进行比较，从而在微观和宏观尺度之间建立联系。使用数值模拟，将模拟实验室实验，并提取相关的物理参数，以便使用数值模拟扩大实验室观察。最后，数据驱动的机器学习技术将用于研究诱发滑动事件之前的连续声发射波形数据。纯数据驱动的方法将消除对如何分析数据的任何先入为主的观念，并可能提供新的见解，有助于阐明流体诱导断层重新激活的过程。这一研究项目将提高对关键过程的理解，使资源行业得到更好的监管，减轻对人类和环境的影响。这将为这些资源和绿色科技产业带来新的经济增长机会。此外，他们还将为公共政策提供见解，以降低这些地震的可能性，改善公共健康和安全。

The number of earthquakes in North America has increased dramatically over the past decade, where many of these earthquakes are large enough to be felt by humans at the surface and damage has been caused in some cases. These events have been termed induced seismicity and result from slip along a pre-existing fault, which is caused by fluid-induced stress changes along that fault. The observed increase of induced seismicity has primarily been linked to wastewater disposal; however, induced seismicity has also been linked both domestically and abroad to hydraulic fracturing and enhanced geothermal systems (EGS). Conversely, as combating global climate change remains a central political issue in the 21st century, the race is on to find suitable renewable energy alternatives of which EGS is one. As a result, injection-induced seismicity and its impact on human populations and the environment will continue to be a central issue in the years to come. To better regulate these industries and minimize negative societal and environmental impacts, fundamental research is required to understand better the key processes that lead to induced earthquakes and how they unfold in the natural environment. This is the overarching objective of the proposed project. The long-term goal of this research program is to improve our understanding of fluid-induced seismicity through novel laboratory experiments, the use and development of data analysis techniques and numerical modelling, and to close the gap between laboratory experimentation and geophysical observations. A series of novel fluid injection experiments on natural and saw-cut faults will be conducted to study the fault reactivation processes where measurements of acoustic emission (AE), ultrasonic velocity, fault displacement, stress, fluid pressure, and injection rate will be collected. AE sensors will be calibrated which will enable comparisons with field-scale seismicity, thereby establishing a link between micro and macro scales. Using numerical modelling, laboratory experiments will be simulated and the relevant physical parameters extracted allowing for laboratory observations to be scaled up using numerical modelling. Lastly, data-driven machine learning techniques will be used to study continuous AE waveform data in the period leading up to an induced slip event. A purely data-driven approach will eliminate any preconceptions about how the data ought to be analyzed and may deliver new insights helping to shed light on the process of fluid-induced fault reactivation. This research program will lead to an improved understanding of critical processes, allowing the resource industry to be better regulated and human and environmental impacts mitigated. The result will be new economic growth opportunities in these resource and green tech industries. Additionally, they will provide insight to inform public policy related to lowering the potential of these earthquakes and improving public health and safety.