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

过去十年，北美的地震数量急剧增加，其中许多地震的震级大到人们在地表都能感觉到，在某些情况下还造成了破坏。这些事件被称为诱发地震活动，是沿着先前存在的断层滑动的结果，而滑动是由沿该断层的流体诱导的应力变化引起的。观测到的诱发地震活动的增加主要与废水处理有关；然而，国内外的诱发地震活动也与水力压裂和强化的地热系统有关。相反，由于抗击全球气候变化仍是21世纪的核心政治问题，人们正在竞相寻找合适的可再生能源替代品，EGS就是其中之一。因此，注射引起的地震活动及其对人类人口和环境的影响在未来几年仍将是一个中心问题。为了更好地监管这些行业并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。这是拟议项目的总体目标。这一研究计划的长期目标是通过新颖的实验室实验、数据分析技术和数值模拟的使用和发展来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。将在天然断层和锯齿状断层上进行一系列新颖的注液实验，以研究断层的再激活过程，其中将收集声发射(AE)、超声波速度、断层位移、应力、流体压力和注入速度的测量结果。将对声发射传感器进行校准，使之能够与现场尺度的地震活动进行比较，从而在微观尺度和宏观尺度之间建立联系。利用数值模型，将模拟实验室实验，并提取相关的物理参数，以便利用数值模型扩大实验室观测的规模。最后，将使用数据驱动的机器学习技术来研究诱发滑动事件之前的连续声发射波形数据。一种纯粹的数据驱动方法将消除关于应该如何分析数据的任何先入为主的想法，并可能提供新的见解，有助于阐明流体诱导的断层重新激活的过程。这项研究计划将导致对关键过程的更好理解，使资源行业得到更好的监管，并减轻对人类和环境的影响。其结果将是这些资源和绿色科技行业出现新的经济增长机会。此外，它们还将提供洞察力，为与降低这些地震的可能性和改善公共卫生和安全相关的公共政策提供信息。

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.