US-Italy planning visit to develop a new international collaboration to improve understanding of fault mechanics and earthquake hazards

大而破坏性的地震是由地球表面附近岩石断层的突然位移（即滑动）引起的。然而，并不是所有的断层滑动都是突然的。事实上，对于一些断层，可以在不震动地面的情况下发生明显的滑动，这使得使用传统的地震仪很难探测到它们。了解这两种类型的断层滑动行为之间的差异，对于我们评估世界范围内活动断层带（包括美国的许多危险断层带）所构成的潜在地震威胁的能力至关重要。位于意大利中部的上蒂伯里纳断层是一个断层频繁滑动而不引起大地震的最好例子之一。这个断层的不寻常的几何形状使它成为世界上最容易利用近地表观测进行研究的断层之一，为研究断层的物理特征提供了一个独特的机会，这些断层会随着地面的剧烈震动而滑动，也会不剧烈震动地面。它是记录断层对破坏性地震构成最大威胁的条件的理想目标。这项新的合作将在美国国家科学基金会催化新国际合作（CNIC）项目的支持下进行，为部署一个现代应变仪仪器网络奠定了基础，该网络专门设计用于在广泛的断层行为范围内检测阿尔托蒂伯里纳断层上的小但可诊断的滑动事件。当与意大利合作伙伴已经部署的现有地震仪和大地测量技术相结合时，新的应变仪网络将允许首次测量滑动事件的频率、持续时间和震级，以及它们与地面运动和地震的关系。了解断层滑动行为的第一项任务是建立一份谅解备忘录，概述国际合作的所有方面，包括：资助、选址、许可、遥测、数据流和存档、日常现场维护、数据处理和科学合作的角色和责任。即将建立的正式合作将(1)为来自美国机构的处于职业生涯早期和中期的研究人员增加未来的研究机会，(2)为美国的下一代地震断层研究人员做好准备，(3)为未来的美国科学家提供在职业生涯早期超越政治边界的重要专业经验。(4)产生丰富的新信息，为美国各地的地震危害评估提供信息。

Large and damaging earthquakes are caused by abrupt displacement (i.e., slip) across faults in the rocks near Earth's surface. However, not all slip across faults is abrupt. Indeed, for some faults, appreciable slip may occur without shaking the ground making them difficult to detect using traditional seismograph instruments. Understanding the difference between these two types of fault slip behavior is critical to our ability to gauge potential earthquake threats posed by active fault zones worldwide, including numerous hazardous fault zones in the United States. One of the best examples of a fault that appears to frequently slip with and without creating large earthquakes is the Alto Tiberina fault located in central Italy. The unusual geometry of this fault, which makes it among the most accessible faults in the world to studies using near surface observations, provides a unique opportunity to investigate the physical characteristics of faults that slide with and without violently shaking the ground. It is an ideal target for documenting the conditions under which faults pose the greatest threat of damaging earthquakes. The new collaboration that will be forged with support from the National Science Foundation Catalyzing New International Collaborations (CNIC) program sets the stage for the deployment of a network of modern strainmeter instruments designed specifically to detect small but diagnostic slip events on the Alto Tiberina fault across a very broad spectrum of fault behaviors. When combined with existing seismograph and geodetic technologies that have already been deployed by Italian partners, the new strainmeter network will allow for the first time measurements of the frequency, duration, and magnitude of sliding events, and their relationship to ground motion and earthquakes. The first task toward understanding fault slip behavior is the establishment of a Memorandum of Understanding outlining all aspects of the international collaboration, including: the roles and responsibilities for funding, siting, permitting, telemetry, data flow and archiving, routine site maintenance, data processing, and scientific collaboration. The formal collaboration that will be established will (1) enhance future research opportunities for early- and mid-career researchers from US-based institutions, (2) prepare the next generation of earthquake fault researchers in the United States, (3) provide future generations of United States scientists with significant professional experience beyond political borders early in their careers, and (4) generate a wealth of new information that will inform earthquake hazards assessments throughout the United States.