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

在过去十年中，北美的地震数量急剧增加，其中许多地震大到足以让地面上的人类感受到，并在某些情况下造成了破坏。这些事件被称为诱发地震活动性，是由于沿着预先存在的断层沿着滑动而引起的，而这种滑动是由沿着该断层的流体诱发应力变化沿着引起的。所观察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地热系统有关。相反，由于应对全球气候变化仍然是21世纪世纪的一个中心政治问题，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，注射引发的地震活动及其对人口和环境的影响将继续是今后几年的一个中心问题。为了更好地监管这些行业并尽量减少负面的社会和环境影响，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在自然环境中如何展开。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颖的实验室实验，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。一系列新的天然和锯切故障的流体注入实验将进行研究的故障复活过程中的声发射（AE），超声波速度，断层位移，应力，流体压力和注入速率的测量将被收集。将校准声发射传感器，以便与现场规模的地震活动进行比较，从而建立微观和宏观尺度之间的联系。将利用数值模型模拟实验室实验，并提取相关物理参数，以便利用数值模型扩大实验室观测。最后，数据驱动的机器学习技术将用于研究诱导滑动事件发生前的连续AE波形数据。纯粹的数据驱动方法将消除有关数据应如何分析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再激活的过程。该研究计划将导致对关键流程的更好理解，使资源行业得到更好的监管，减轻对人类和环境的影响。其结果将是在这些资源和绿色技术产业中出现新的经济增长机会。此外，他们将提供洞察力，为有关降低这些地震的可能性和改善公共卫生和安全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.