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Pedestrian tsunami evacuation results for two tsunami-inundation zones (2009 and probable maximum tsunami (PMT)) and four travel speeds (slow walk, fast walk, slow run, and fast run) for American Samoa

October 2, 2018

This data release is comprised of a set of eight time travel map shapefiles (two tsunami inundation zones and four travel times) for use in GIS software applications and two population exposure by travel time tables (residents and nonresidences) for use in GIS software applications and other standalone spreadsheet applications. The travel time map was generated using the Pedestrian Evacuation Analyst model (version 1.0.1 for ArcGIS 10.5) from the USGS (https://geography.wr.usgs.gov/science/vulnerability/tools.html). The travel time analysis uses ESRI's Path Distance tool to find the shortest distance across a cost surface from any point in the hazard zone to a safe zone. This cost analysis considers the direction of movement and assigns a higher cost to steeper slopes, based on a table contained within the model. The analysis also adds in the energy costs of crossing different types of land cover, assuming that less energy is expended walking along a road than walking across a sandy beach. To produce the time map, the evacuation surface output from the model is grouped into 1-minute increments for easier visualization. The times in the attribute table represent the estimated time to travel on foot to the nearest safe zone at the speed designated in the map title. The file name indicates whether the map is of the recreated tsunami inundation zone for the 2009 Mw 8.1 Samoa earthquake or a probable maximum tsunami (PMT) inundation zone for American Samoa and which travel speed was used in the modelling (slow walk, fast walk, slow run, or fast run). The resident exposure by travel time dataset contains American Samoa resident count estimates as a function of travel time out of the 2009 and probable maximum tsunami (PMT) inundation zones for four different travel speeds (slow walk, fast walk, slow run, and fast run). The data are organized in a manner which permits summarizing or visualizing the data by village, tsunami-evacuation zone, and/or travel time, with individual rows representing the number of residents present in the specific village/evacuation zone/travel time combination. Due to the nature of the methodology used to distribute residential population to structures, resident numbers are not integers. The nonresidence site exposure by travel time dataset contains American Samoa nonresidence count estimates as a function of travel time out of the 2009 and probable maximum tsunami (PMT) inundation zones for four different travel speeds (slow walk, fast walk, slow run, and fast run). The data are organized in a manner which permits summarizing or visualizing the data by business classification (church, community center, education, health care center, hotel, industrial, office, recreation, shelter, and store), tsunami-evacuation zone, and/or travel speed, with business details and evacuation zone/travel speed combinations listed across the top as columns and individual rows representing unique businesses' details in the different evacuation zone/travel speed combinations. These data support the following publication: Wood, N.J., Jones, J.M., Yamazaki, Y., Cheung, K-F., Brown, J., Jones, J.L., and Abdollahian, N., 2018, Population vulnerability to tsunami hazards informed by previous and projected disasters - a case study of American Samoa: Natural Hazards, 24 p., https://doi.org/10.1007/s11069-018-3493-7.