DOI: 10.7910/dvn/fy8art
title: Rockfall Activity Rate System Analysis for Scenario Earthquakes in Alaska

description: : Rockfall is a chronic slope hazard along transportation corridors throughout the Pacific Northwest (PNW), resulting in frequent road closures and lane restrictions, and directly impacting driver safety, mobility, and accessibility for many critical lifelines. These impacts are amplified by moderate- to large-magnitude seismic events – both during and after shaking, making earthquakes a driver of persistent rockfall hazards. 
The recent Canterbury, New Zealand Earthquake Sequence triggered many thousands of rockfalls, which resulted in the unfortunate loss of life and significantly damaged motorways, residential dwellings, and commercial structures. Detailed 3D terrestrial lidar scan surveys were periodically collected at several rock slope sites throughout the Port Hills in Christchurch, New Zealand, to document the rockfall activity as well as assess the post-earthquake stability of the slopes. This dataset spans five years of seismic activity that includes several large earthquakes but lacks critical pre-event baseline data. Analysis of this dataset indicates that the activity rates and volume of material leaving the cliff occurred at heightened levels following shaking and decayed with time. Through regression analyses based on correlating volume loss observed in New Zealand with readily obtainable variables of slope height, slope angle, geomorphic erosion rates, and peak ground acceleration (PGA), a rapid forecasting system called the RoARS was developed by the research team (Olsen et al. 2020, Massey et al. 2022). As an example, RoARS was applied along a highway corridor in Oregon, U.S.A. to predict the potential increases in rockfall activity and volumes resulting from a major earthquake as well as an estimate of the time to return to baseline conditions for rockfall activity. This information was provided in a geographic information system (GIS) framework, which subsequently can be integrated into transportation network analysis to predict the economic and environmental impacts resulting from mobility loss due to partial or full highway closures at these locations due to increased rockfall activity.
These data are the analysis results applying the RoARS method to rock slope sites in two Alaskan transportation corridors to evaluate coseismic and post-seismic rockfall hazard at a regional scale, as well as estimate rockfall volumes and associated closure times. We used a rock slope inventory provided by the Alaska Department of Transportation and Public Facilities and maps of predicted ground motions from the Alaska Earthquake Center as input. Additional slope metrics were extracted from public lidar data. Table 1 summarizes the scenarios analyzed as well as the scenario codes (e.g., LL71). These data consist of a GIS geodatabase containing a point feature for each scenario. Substantial uncertainty exists in the data given they are scenario events; however, this database and model creation explores a new avenue for decision-makers to evaluate potential rockfall scenarios considering seismic disturbance, and consequently, plan accordingly for closures and restoration of mobility following shaking.
description: This database contains information provided by other sources in addition to the analysis completed by the research team: 
• The base rock slope inventory used in this analysis was provided by Alaska Department of Transportation and Public Facilities. Available at: https://akdot.maps.arcgis.com/apps/MinimalGallery/index.html?appid=61ce3c7a1dfe4e2ba8ea0cdd896fbe39 
• Maps of predicted peak ground acceleration from scenario events used in this analysis were provided by the Alaska Earthquake Center. https://earthquake.alaska.edu/
• Elevation information was obtained from the Alaska Division of Geological & Geophysical Surveys: https://elevation.alaska.gov/


http://hdl.handle.net/1773/49786