NSFGEO-NERC: Collaborative Research: The central Apennines Earthquake cascade under a new microscope

2016年8月至2017年1月，意大利中部的亚平宁山脉发生了一系列强烈地震，造成人员伤亡，并对阿马特里斯，Accumoli和Norcia等历史城镇造成严重破坏。这一系列地震在五个月的时间里发生了六次强烈地震，当时正在进行应对和恢复工作。 这种迅速演变的地震危机强调了更好地了解地震序列如何展开的迫切需要。这个由美国国家科学基金会和英国国家环境研究理事会资助的联合项目的目标是，与意大利国家地质和火山研究所合作，将通过研究这些破坏性地震加深对地震相互作用的认识。一个国际地震专家小组将利用地震序列期间记录的高质量地震数据，开发新的方法，以解决目前的障碍，这些障碍不仅阻碍了对地震过程的深入了解，而且还推迟了震后灾害环境中的科学反应。在该项目中开发的在几个小时内检测、定位和描述最小震级事件的观测能力将直接适用于美国和世界各地的构造、诱发、地热和火山地震活动。这项研究的结果将使改善和科学知情的反应，下一次地震危机袭击美国通过现有的伙伴关系与美国。S.本研究通过分析高分辨率地震目录来测试日益复杂的地震预测模型，从而研究复杂地震序列的物理特性。 为了实现这一目标，该项目将：1）使用最先进的技术为2016-2017年袭击意大利亚平宁山脉的破坏性地震序列开发一个全面的高分辨率地震目录; 2）调查地震触发的物理学和该序列中大规模事件的演变; 3）开发和提供可测试的预测模型，以支持未来地震序列的决策过程。该研究将使用部署在震中地区的85个高质量宽带传感器记录的无与伦比的地震数据集，以分析序列中的每个地震如何对地震活动性在空间和时间上的演变做出贡献。 该序列在这方面特别丰富，在2016年8月24日，2016年10月26日至28日和2017年1月18日有空间交织的情节。大型和小型事件的地震图将使我们能够开发和测试新的基于全波形的事件检测，定位和表征算法，即使是最小震级的事件也会产生精确的震源参数和断层机制。通过提高整个震级谱的震源参数的质量，可以应用基于过程的地震成核和相互作用模型，包括断层复杂性、断层加载、松弛、应力相互作用和断层对应力扰动的敏感性的作用，以了解该序列的演变。对断层力学的进一步理解将有助于开发创新的基于物理的预测模型。目前，描述短期聚集概率的实时地震预报主要基于统计/经验模型。然而，这些模型缺乏一个基本的物理模型，因此，如果没有潜在的地震活动存在的可预测性有限。基于常规目录的物理预测和统计预测的共同挑战是所产生的概率的低概率和高不确定性。在这种情况下，决策和科学咨询都受到严重阻碍。因此，使用2016-2017年意大利地震序列的最新地震目录来测试空间和时间的物理，统计和混合（物理和统计）预测将有助于（a）测试地震发生序列的物理模型，以及（B）提高预测的分辨率，准确性和技能。该项目的广泛影响包括改进地震风险评估以及促进美国和欧洲地震学家之间的合作。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

A series of powerful earthquakes rocked the Apennine mountains in central Italy, between August 2016 and January 2017 causing loss of life and inflicting heavy damage to the historic towns of Amatrice, Accumoli and Norcia. This sequence produced six strong earthquakes over a period of five months as response and recovery operations were underway. This rapidly evolving seismic crisis underscores the pressing need to better understand how earthquake sequences unfold. The goal of this joint project, funded by the National Science Foundation in the U.S. and the National Environmental Research Council in the U.K., in coordination with the Istituto Nazionale di Geofisica e Volcanologia in Italy, will deepen knowledge of earthquake interaction by studying these devastating earthquakes. An international team of earthquake expertss will use high-quality seismic data recorded during the sequences to develop new approaches that can address current obstacles that not only impede deep understanding of the earthquake processes, but also delay the scientific response in the post-earthquake disaster environment. The observational capability to detect, locate and characterize even the smallest magnitude events within few hours developed in this project will be directly applicable to tectonic, induced, geothermal and volcanic seismicity in the U.S. and around the world. Findings of this research will enable improved and scientifically-informed response to the next earthquake crisis to strike the U.S. through existing partnership with the U. S. Geological Survey and support international collaboration amongst US and European earthquake researchers.This study investigates the physics of complex earthquake sequences through the analysis of high-resolution earthquake catalogs to test increasingly sophisticated earthquake forecasting models. To reach this goal this project will: 1) Use state-of-the-art techniques to develop a comprehensive high-resolution earthquake catalog for the devastating earthquake sequence that struck the Italian Apennines in 2016-2017; 2) Investigate the physics of earthquake triggering and the evolution of large-magnitude events within this sequence; 3) Develop and provide testable forecast models that can support decision-making process for future earthquake sequences. The reseach will use the unparalleled seismic data set recorded by more than 85 high-quality broadband sensors deployed in the epicentral region to analyze how each earthquake in the sequence contributes to the evolution of seismicity in space and time. This sequence is particularly rich in this regard, with spatially intertwined episodes on August 24, 2016, October 26-28, 2016 and January 18, 2017. The seismograms of both large and small events will enable us to develop and test new full-waveform based algorithms for event detection, location and characterization that will yield precise source parameters and faulting mechanisms for even the smallest magnitude events. By improving the quality of seismic source parameters across the magnitude spectrum it will be possible to apply process-based models of earthquake nucleation and interaction, including the role of fault complexity, fault loading, relaxation, stress interaction, and fault susceptibility to stress perturbation to understand the evolution of this sequence. The improved fault mechanical understanding will help to develop innovative physics-based forecast models. Currently, real-time earthquake forecasts that describe short-term clustering probabilities are based predominantly on statistical/empirical models. However, these models lack an underlying physical model and therefore have limited predictability if no precursory seismicity exists. A common challenge for both physics- based and statistical forecasts that are based on routine catalogues is the low-probability and high-uncertainty nature of the resulting probabilities. Decision-making and scientific advice are all severely hampered under these conditions. Thus, using this new state-of the art earthquake catalog of the 2016-2017 Italian sequence to test physical, statistical and hybrid (physical and statistical) forecasts in space and time will help (a) to test physical models for earthquake occurrences in sequences, and (b) improve the resolution, accuracy and skill of the forecasts. The broader impacts of this project include improvement on seismic risk assessment as well as fostering collaboration between US and European seismologists.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.