Simulated inundation extent and depth at Whittier, Alaska resulting from the hypothetical rapid motion of landslides into Barry Arm Fjord, Prince William Sound, Alaska

Summary
This data release contains postprocessed model output from simulations of hypothetical rapid motion of landslides, subsequent wave generation, and wave propagation. A tsunami wave was generated with rapid motion of unstable material into Barry Arm Fjord, this wave then propagated through Prince William Sound, including into Passage Canal east of Whittier. Here we consider only the largest wave generating scenario presented by Barnhart and others (2021a, 2021b) and use a simulation setup similar to that work. The results presented here are not identical to those presented in Barnhart and others (2021a, 2021b) because the results presented here use an expanded dataset of topography and bathymetry. 
Model Description
The simulation used the D-Claw model (George and Iverson, 2014; Iverson and George, 2014). D-Claw is a single layer model which simulates the coupled evolution of fluid and solid material while satisfying mass and momentum conservation. It is capable of simulating motion of landslide material, interaction of that material with water, tsunami generation, and wave propagation. Because the mobile material in D-Claw may be water, landslide material, or a mixture between the two, we will use the term "wave height” to refer to the altitude of the mobile material surface, regardless of its composition.
Considered Scenario and Model Implementation
We present results from a single scenario (Table 1). This scenario used the landslide source characteristics of the larger, contractive, more mobile scenario C-689 from Barnhart and others (2021a, 2021b) which generated the largest wave. In this scenario, three landslides on an unstable slope northwest of the northern portion Barry Arm fjord concurrently move into the fjord, generating a tsunami wave.
The D-Claw model supports adaptive mesh refine¬ment, and like Barnhart and others (2021a, 2021b) we used a computational grid cell size of 50 m around the landslide and along the wave propagation path. Our implementation differs from this prior work in that we permitted grid refinement to a finer resolution of 1 m as the tsunami wave approached and inundated Whittier, Alaska. In the portions of the domain where no wave propagated, the cell size was permitted to remain at a coarse resolution of 1,000 m.
The spatial extent of the simulation domain (shown in Figure 1) is smaller than what was considered by Barnhart and others (2021a, 2021b) and does not cover all of Prince William Sound. Instead, it is limited to the region between Whittier and Barry Arm. Additionally, the duration of simulated time was reduced relative to that presented in Barnhart and others (2021a, 2021b). Simulations ran for 35 minutes of simulated time, reflecting the arrival of the largest wave within the two hours of total simulated time presented by Barnhart and others (2021a, their Figures 7 and 8).
Description of Inundation
The simulation results show very little inundation at Whittier, Alaska. In the simulations, the parking area to the north of the City of Whittier Campground was inundated by less than 1 m of water. Along the sea wall defining and protecting the harbor, along Camp Road to the west of town and at the airstrip, simulated water levels rose to ~2 m above the MHHW level. At the harbor, the simulated wave did not propagate inland of the sea wall. Similarly, the simulated wave did not reach the elevation of Camp Road or the waiting area at the east portal of the Anton Anderson Memorial Tunnel. Finally, the simulated wave did not inundate the airstrip.
Reference frame
The horizontal reference frame for all files is North American Datum of 1983 (NAD 83) Universal Transverse Mercator (UTM) Zone 6 N (European Petroleum Survey Group Code 26906). The vertical reference frame is mean higher high water (MHHW) at Whittier, Alaska (NOAA Station 9454949). At this station, mean higher high water is defined as 3.395 m above the North American Vertical Datum of 1988. Elevation, altitude, and height, as used in this data release, refer to distance above the MHHW vertical datum.
Topographic and Bathymetric Data Sources
This work relied on integrating multiple topographic and bathymetric data sources. Where original data sources were not provided in the reference frame used in this work, datasets were reprojected to NAD 83 UTM Zone 6 N and translated to MHHW. 
In Barry Arm fjord north of Port Wells, we used a digital terrain model derived from subaerial light detection and ranging (lidar) data collected on June 26, 2020 (Daanen and others, 2021) and submarine bathymetric data collected between August 12 and 23 (NOAA, 2020). These data were combined at 5 m horizontal resolution.
In Passage Canal west of 148.5º W—including at Whittier, Alaska—we use a 1 m topobathymetric dataset described by Haeussler and others (2013). This dataset combines a digital terrain model derived from lidar data collected between October 21 and 25, 2012 (Hubbard and others, 2013) with submarine multibeam data collected in 2011 (Haeussler and others, 2013), and digitized National Ocean Service (NOS) smooth sheet bathymetry for Survey H-10655 (NOAA, 1995). 
Elsewhere in the domain, we used the 8/3 arc-second dataset for Prince William Sound (NOAA, 2009a) and the 8/15 arc-second dataset for Whittier and Passage Canal (NOAA, 2009b). These data were projected into UTM coordinates at a resolution of 50 m for the Prince William Sound dataset and 10 m for the Whittier Dataset. 
These topographic and bathymetric data sources differ from those used by Barnhart and others (2021a, 2021b) in the addition of the 1 m resolution dataset used near Whittier, Alaska and in Passage Canal (green polygon in Figure 1). All other data sources were used by Barnhart and others (2021a, 2021b).
Results
Herein, we provide two model result files of spatially distributed model output in GeoTiff format and one polyline shapefile for scenario C-689 (Table 1). The shapefile delineates the boundary between model grid cells that were, and were not, inundated during the simulation. The two GeoTiff files contain the following variables: maximum wave height and the maximum inundation depth for model grid cells which started dry and were inundated by water or landslide material at some point in the simulation. 
The results are presented only in the region surrounding Whittier, Alaska and at a 1 m spatial resolution. The extent of the region surrounding Whittier, Alaska where results are provided is given in the east-west direction by eastings 405500—409700 and in the north-south direction by northings 6738600—6740500. The inundation extent is also shown in Figure 2. 
In addition, we provide time series from three numerical gages located between the junction of Passage Canal and Port Wells and the Whitter, Alaska harbor. 
Inundation extent
The file “C689_1m_inund_extent.shp” is an ESRI Shapefile containing a polyline demarcating the boundary between areas which were inundated and areas which were not inundated. It was constructed by delineating the boundary between where “inundated_depth.tif” was greater than zero and where it was less than zero. 
Inundated depth
The file “inundated_depth_meters.tif” contains the maximum inundation depth for grid cells which started dry but were inundated at some point in the simulation. The maximum inundation depth was calculated by analyzing model output at 15 second increments and identifying the maximum inundation depth over all output timesteps. Model grid cells which were never inundated or which started as ocean are indicated with “no data”. 
The file "maximum_wave_height_meters.tif" contains the maximum wave height. The wave height is given in meters relative to the vertical reference frame datum. The maximum wave height was calculated by analyzing model output at 15 second increments and identifying the maximum wave height over all output timesteps. Model grid cells which were never inundated by water or landslide material are indicated with "no data". The maximum wave height reflects the sum of the inundation depth and the grid cell elevation. Note that in grid cells which were initially dry but were inundated later, this value does not reflect the inundation depth.
Wave height time series
The file "whittier_passage_canal_gages.csv" contains simulated wave height time series for three locations where numerical gages were placed in the simulation (Figure 3). Latitude, longitude, easting, and northing coordinates for each of the three numerical gage locations are provided in Table 2. 
The file "gages.csv" contains four columns:
1.	The first column "scenario" contains a string representing the scenario. In this case only one scenario was considered: "C689”.
2.	The second column "gage_id" contains an integer referring to the gage ID number (1, 2, or 3) 
3.	The third column "time_seconds" contains an integer indicating the simulation time in seconds. 
4.	The fourth column "waveheight_meters" contains a floating-point number indicating the simulated wave height in meters above a reference datum.
References Cited
Barnhart, K.R., Jones, R.P., George, D.L., Coe, J.A., and Staley, D.M., 2021a, Preliminary assessment of the wave generating potential from landslides at Barry Arm, Prince William Sound, Alaska: U.S. Geological Survey Open-File Report 2021–1071, 28 p., accessed July 22, 2021 at https://doi.org/10.3133/ ofr20211071.
Barnhart, K.R., Jones, R.P., George, D.L., Coe, J.A., Staley, D.A., 2021b, Select model results from simulations of hypothetical rapid failures of landslides into Barry Arm Fjord, Prince William Sound, Alaska: U.S. Geological Survey data release, accessed July 22, 2021 at https://doi.org/10.5066/P9XVJDNP.
Daanen, R.P., Wolken, G.J., Wikstrom Jones, K., and Herbst, A.M., 2021, High resolution lidar-derived elevation data for Barry Arm landslide, southcentral Alaska, June 26, 2020: Alaska Division of Geological &amp; Geophysical Surveys Raw Data File 2021–3, 9 p., accessed June 17, 2021, at https://doi.org/10.14509/30593.
George, D.L., and Iverson, R.M., 2014, A depth-averaged debris-flow model that includes the effects of evolving dilatancy—II. Numerical predictions and experimental tests: Proceedings of the Royal Society of London. Series A, v. 470, no. 2170, p. 20130820, accessed June 17, 2021, at https://doi.org/ 10.1098/rspa.2013.0820.
Iverson, R.M., and George, D.L., 2014, A depth-averaged debris-flow model that includes the effects of evolving dilatancy—I. Physical basis: Proceedings of the Royal Society of London. Series A, v. 470, no. 2170, p. 20130819, accessed June 17, 2021, at https://doi.org/ 10.1098/rspa.2013.0819.
Haeussler, P. J., Parsons, T., Finlayson, D. P., Hart, P., Chaytor, J. D., Ryan, H., Lee, H., Labay, K., Peterson, A., and Liberty, L., 2013, New Imaging of Submarine Landslides from the 1964 Earthquake Near Whittier, Alaska, and a Comparison to Failures in Other Alaskan Fjords: Advances in Natural and Technological Hazards Research, p. 361–370, accessed July 22, 2021 at https://doi.org/10.1007/978-3-319-00972-8_32
Hubbard, T.D., Wolken, G.J., Stevens, D.S.P., and Combellick, R.A., 2013, High-resolution lidar data for the Whittier area, Passage Canal, and Portage Lake, Alaska: Alaska Division of Geological &amp; Geophysical Surveys Raw Data File 2013-3, 5 p, accessed July 22, 2021 at https://doi.org/10.14509/24976.
National Oceanic and Atmospheric Administration [NOAA], 1995, Report for H10655: National Oceanic and Atmospheric Administration [NOAA] web page, accessed July 22, 2021, at https://www.ngdc.noaa.gov/nos/H10001-H12000/H10655.html.
National Oceanic and Atmospheric Administration [NOAA], 2020, Report for H13396: National Oceanic and Atmospheric Administration [NOAA] web page, accessed April 5, 2021, at https://www.ngdc.noaa.gov/ nos/ H12001- H14000/ H13396.html.
National Oceanic and Atmospheric Administration [NOAA] National Geophysical Data Center, 2009a, Prince William Sound, Alaska 8/3 arc-second MHHW coastal digital elevation model: National Oceanic and Atmospheric Administration [NOAA], National Centers for Environmental Information web page, accessed April 5, 2021, at https://data.noaa.gov/metaview/page?xml=NOAA/NESDIS/NGDC/MGG/DEM//iso/xml/638.xml&amp;view= getDataView&amp;header= none.
National Oceanic and Atmospheric Administration [NOAA] National Geophysical Data Center, 2009b, Whittier, Alaska 8/15 arc-second MHHW coastal digital elevation model: National Oceanic and Atmospheric Administration [NOAA], National Centers for Environmental Information web page, accessed April 5, 2021, at https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ngdc.m gg.dem:530.

Tags: alaska, barry-arm, biota, d-claw, inundation, landslide, prince-william-sound, simulation-results, tsunami, usgs-612eaf03d34e40dd9c094949, whittier-alaska
Organization: Department of the Interior