RAPID: Quantifying Temporal Changes in Rockfall Magnitude-Frequencies for Well-Characterized Rockslopes Shaken by the 2018 Alaska Earthquake

RAPID：量化 2018 年阿拉斯加地震震动的特征明确的岩坡落石震级频率的时间变化

• 批准号: 1929304
• 负责人: Ben Leshchinsky
• 金额: $ 5.5万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-15 至 2020-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1929304&HistoricalAwards=false
• 关键词: RAPID; Quantifying; Temporal; Changes; Rockfall

Earthquakes cause many hazards during shaking, but some of the hazards linger long after the seismic event is over. For example, heightened frequency of landslides and rockfalls commonly occur in the months - and even years - following an earthquake. This Rapid Response Research (RAPID) project seeks to capture perishable data from several rock slopes highly susceptible to rockfall that were affected by the recent earthquake in Anchorage. By doing this, we may compare the rate and frequency of rockfall occurrence to pre-earthquake levels in order to better understand how much rockfall activity increases following shaking, and how long it takes to return to pre-earthquake levels. This has implications for post-earthquake recovery and seismic resilience throughout much of the US and abroad. Earthquakes often trigger significant rockfall activity in steep cliffs. The recent 2018 November 30th Alaska earthquake caused significant shaking (up to 0.4g) across the Anchorage region, resulting in numerous rockfalls, landslides, and lateral spreads. The combination of potentially large volumes, high velocities, long travel distances, and impact forces make the rockfall hazard significant. Based on observations from past events in New Zealand, it is believed that rockfall activity over at least the next several months will exceed "normal" baseline levels before decreasing. Nevertheless, as is often the case, the previous research does not have detailed baseline information prior to the event. This prior research begs three primary scientific questions: what is "baseline" rockfall activity? How does shaking translate to increased rockfall activity, magnitude, and frequency particularly in the heterogenous geologic conditions encountered in the rock slopes surrounding Anchorage? And lastly, how quickly does rockfall activity and magnitude return to baseline conditions? This project seeks to collect rockfall activity rates through repeat terrestrial laser scanning at well-characterized rockfall sites near Anchorage. Change detection will be performed and the rate of rockfall activity characterized in comparison to previous epochs and the serial data collected as part of this project. With existing baseline data not influenced by recent seismic activity, we will characterize and compare the activity rate following shaking. This investigation will provide fundamental knowledge about the process that dictates both the increase and decay in rockfall activity after seismic disturbance. The resulting knowledge will provide data needed to support and advance modern performance- and risk-based extreme event design methodologies.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.

地震在摇晃过程中会造成许多危害，但有些危害在地震事件结束后仍会持续很长时间。例如，地震后的数月甚至数年内，山体滑坡和落石的频率通常会增加。这个快速反应研究（RAPID）项目旨在从几个岩石斜坡捕捉易腐数据，这些岩石斜坡非常容易受到最近安克雷奇地震的影响。通过这样做，我们可以将落石发生的速率和频率与震前水平进行比较，以便更好地了解摇晃后落石活动增加了多少，以及恢复到震前水平需要多长时间。 这对美国大部分地区和国外的震后恢复和地震恢复能力都有影响。 地震经常在陡峭的悬崖上引发重大的落石活动。最近的2018年11月30日阿拉斯加地震在安克雷奇地区造成了显著的震动（高达0.4g），导致了许多岩石倒塌，山体滑坡和横向蔓延。潜在的大体积、高速度、长行驶距离和冲击力的结合使得落石危险很大。根据对新西兰过去发生的事件的观察，据信至少在未来几个月内，落石活动将超过“正常”基线水平，然后才会减少。然而，与通常情况一样，以前的研究没有事件发生前的详细基线信息。这项先前的研究回避了三个主要的科学问题：什么是“基线”落石活动？震动如何转化为落石活动、强度和频率的增加，特别是在锚碇周围岩石边坡遇到的非均匀地质条件下？最后，落石活动和强度恢复到基线条件的速度有多快？ 该项目旨在收集落石活动率，通过重复地面激光扫描在安克雷奇附近的落石地点的特点。将进行变化检测，并将落石活动的速率与以前的时期和作为本项目一部分收集的系列数据进行比较。利用现有的基线数据不受最近地震活动的影响，我们将描述和比较地震后的活动率。这项调查将提供有关过程的基本知识，决定了地震扰动后落石活动的增加和衰减。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。