Collaborative Research: Systematic Comparisons of Regular and Slow Earthquakes in Central and Southern California

本项目旨在了解加州中部和南部的常规地震和慢震的不同行为。最近发现的缓慢地震拓宽了我们对活动断层如何减轻构造应力的看法。通过将各种技术应用于EarthScope和其他永久网络收集的大量地震数据，首席调查员（pi）正在创建更详细的断层带结构图像，这些断层带结构位于常规地震发生的深度内和深度以下。pi还希望更好地了解断层带属性如何控制不同的断层滑动行为（常规与缓慢）。该项目将改进我们对大地震发生时间和地点的估计，并有助于评估未来的地震危害。由于缓慢变形可能发生在大地震之前，更好地跟踪缓慢地震也可以帮助更好地了解与地震如何启动和相互作用相关的过程。pi正在开发新的教程，从地震数据中触发和检测常规地震和慢震。此外，他们正在开发与该项目相关的可视化和听觉地震数据的产品。所有这些活动都有助于吸引下一代科学家进入地震领域，并用最先进的工具训练他们，使他们能够在未来的职业生涯中取得成功。该项目还支持两名研究生的培训以及与日本研究人员的国际合作。新发现的深部构造震动和伴随的慢滑事件改变了我们对发震带下方断层运动释放累积构造应力的看法。自从15年前Earthscope项目开始以来，在加利福尼亚州中部的圣安德烈亚斯断层（SAF）的帕克菲尔德-乔拉梅（Parkfield-Cholame）段，人们就清楚地观察到深度震颤。然而，除了少数情况外，在南加州的圣哈辛托断层（SJF）和其他主要断层上并没有普遍发现震颤。尽管在进一步了解震颤和常规地震的物理机制方面取得了进展，但许多基本问题仍未解决。这些包括：1；控制加州中部和南部不同的震颤和微震行为的主要因素是什么？2. 震颤和低频地震（lfe）与常规地震有何不同？3. 在发生常规地震和缓慢地震的深处，原地断裂带的性质是什么？为了回答这些问题，pi正在使用最先进的技术和这些地区的可用数据集对加利福尼亚中部和南部的常规和缓慢地震进行系统分析。具体而言，pi正在执行以下研究任务：1。在南加州沿SAF和SJF的Parkfield剖面探测和重新定位微地震；2. 更好地探测和定位南加州沿SJF的震颤和生命周期，并将其行为与加州中部进行比较；3. 量化这些地区微震和震颤/生命周期的可触发性；和4。利用Vp/Vs比值等成像方法圈定内部断裂带结构。该项目的目标是获得这两个地区微震和慢震的高精度位置，并利用它们研究它们对外部应力扰动的响应，并获得控制中南加州常规地震和慢震不同行为的原位断裂带性质。此外，pi正在继续开发有关地震触发和探测的在线教程，以及与Earthscope相关的可视化和超声产品。这些活动有助于向广大读者普及地震前沿科学知识，吸引下一代科学家进入地震领域，并用最先进的工具培训他们，使他们能够在未来的职业生涯中取得成功。该项目还支持两名研究生的培训以及与日本研究人员的国际合作。

Nontechnical This project aims to understand different behaviors of regular and slow earthquakes in Central and Southern California. The recent discovery of slow earthquakes broadens our view on how active faults relieve tectonic stresses. By applying various techniques to extensive seismic data collected by EarthScope and other permanent networks, the Principal Investigators (PIs) are creating better images of detailed fault zone structures within and below the depth where regular earthquakes occur. The PIs also hope to better understand how fault zone properties control different fault slip behaviors (regular vs slow). The project will improve our estimation of when and where large earthquakes occur and help to evaluate future seismic hazards. Because slow deformation may occur before large earthquakes, better tracking slow earthquakes could also help to better understand the processes relevant to how earthquakes initiate and interact. The PIs are developing new tutorials on triggering and detection of regular and slow earthquakes from seismic data. In addition, they are developing products to visualize and hear seismic data relevant this project. All these activities help to attract next generation scientists into the seismological field, and train them with state-of-the-art tools so that they can succeed in their future careers. This project also supports training of two graduate students and an international collaboration with Japanese researchers.Technical The newly discovered deep tectonic tremor and accompanying slow-slip events have changed our view on how accumulated tectonic stresses are released through fault movement below the seismogenic zone. Deep tremor has been clearly observed along the Parkfield-Cholame section of the San Andreas Fault (SAF) in Central California since around the time when the Earthscope project started more than 15 years ago. However, except a few cases, tremor has not been ubiquitously found along the San Jacinto Fault (SJF) and other major faults in Southern California. Although progress has been made to further understand the physical mechanisms for tremor and regular earthquakes, many fundamental questions remain open. These include: 1. What are the primary factors that control different tremor and microearthquake behaviors in Central and Southern California? 2. How do tremor and low-frequency earthquakes (LFEs) differ from regular earthquakes? 3. What are in situ fault zone properties at depth where regular and slow earthquakes occur? To answer these questions, the PIs are conducting a systematic analysis of regular and slow earthquakes in Central and Southern California using state-of-the-art techniques and available dataset in these regions. Specifically, the PIs are performing the following research tasks: 1. Detect and relocate microearthquakes along the Parkfield section of the SAF and along the SJF in Southern California; 2. Better detect and locate tremor and LFEs along the SJF in Southern California and compare their behaviors with those in Central California; 3. Quantify the triggerability of microearthquakes and tremor/LFEs in these regions; and 4. Delineate internal fault zone structures using Vp/Vs ratios and other imaging methods.The project goal is to obtain highly accurate locations of microearthquakes and LFEs in both regions, and use them to study their responses to external stress perturbations, and obtain in situ fault zone properties that control different behaviors of regular and slow earthquakes in Central and Southern California. In addition, the PIs are continuing their development of online tutorials on earthquake triggering and detection, and visualization and sonification products related to Earthscope. These activities help to educate general audience with frontier earthquake science, attract next generation scientists into the seismological field, and train them with state-of-the-art tools so that they can succeed in their future careers. This project also supports training of two graduate students and an international collaboration with Japanese researchers.