Select model results from simulations of hypothetical rapid failures of landslides into Barry Arm, Prince William Sound, Alaska

This data release contains model output from simulations presented in the associated Open-File Report (Barnhart and others, 2021). In this report, we present model results from four simulations (scenarios C-290, NC-290, C-689, NC-689, Table 1) of hypothetical rapid movement of landslides into adjacent fjord water at Barry Arm, Alaska using the D-Claw model (George and Iverson, 2014; Iverson and George, 2014). The basis for the four scenarios is described in Barnhart and others (2021). Table 1. Summary of four considered scenarios including key simulation input parameter values. Simulation input parameters Scenario name and description NC-290 C-290 NC-689 C-689 Symbol Units Description Smaller, noncontractive, less mobile Smaller, contractive, more mobile Larger, noncontractive, less mobile Larger, contractive, more mobile alpha degrees Headscarp angle 45 45 60 60 C - Logarithmic spiral coefficient (defined in Equation 2) 1.0 1.0 0.5 0.5 V m3 Volume of all three landslides 290,000,000 290,000,000 689,000,000 689,000,000 m0 - Initial solid volume fraction 0.64 0.62 0.64 0.62 mcrit - Critical state solid volume fraction 0.64 0.64 0.64 0.64 phi degrees Basal friction angle 36 36 36 36 phi delta degrees Basal friction angle offset 10 0 10 0 k0 m2 Hydraulic permeability 10-10 10-10 10-10 10-10 D-Claw simulates the coupled evolution of fluid and solid phases of rapid landslide failures and tsunami generation, while satisfying mass and momentum conservation. Accordingly, the surface of the mobile material is not necessarily water but may reflect 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. Herein, we present six model result files. One file provides timeseries of the wave height for all four scenarios at eight hypothetical gage locations in comma separated value (csv) format. The location of these hypothetical gages is given in Table 2. Five files provide spatially distributed model output in GeoTiff format for scenario C-689 (Table 1). This scenario produced the largest tsunami wave of the considered scenarios. The five files contain the following variables: model grid cell classification, wave arrival time, maximum wave height, time of maximum wave height, and the maximum inundation depth for model grid cells which started dry (no inundation) and were inundated by water and/or landslide material at some point in the simulation. Table 2. Gage locations for file "gages.csv". Gage number Easting Northing Latitude Longitude Description 1 437170 6774969 61.1043 -148.1655 Base of landslide in Barry Arm 2 436983 6772579 61.0828 -148.1682 Junction of Barry Arm and Harriman Fjord 3 437766 6771072 61.0694 -148.1532 Middle of southern Barry Arm 4 438185 6767334 61.0359 -148.1442 Junction of southern Barry Arm and Port Wells 5 439006 6759012 60.9613 -148.1263 Northern Port Wells 6 431189 6740360 60.7926 -148.2640 Southern Port Wells 7 422674 6741853 60.8045 -148.4210 Eastern Passage Canal 8 408443 6739767 60.7827 -148.6814 Passage Canal 500 m offshore Whittier, Alaska The horizontal reference frame for all files is NAD 83 UTM Zone 6 N (EPSG 26906). The vertical reference frame is mean higher high water 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. Altitude and height, as used in this data release, refer to distance above the vertical datum. Wave height time series The file "gages.csv" contains simulated wave height time series for eight locations and four scenarios. The file "gages.csv" contains four columns: The first column "scenario" contains a string representing each of the four scenarios ("C290", "NC290", "C689", or"NC689"). The second column "gage_id" contains an integer referring to the gage ID number (1, 2, 3, 4, 5, 6, 7, or 8) The third column "time_seconds" contains an integer indicating the simulation time in seconds. The fourth column "wave_height_meters" contains a floating-point number indicating the simulated wave height in meters above a reference datum. The following five files contain simulation results for scenario C-689. Latitude, longitude, easting, and northing coordinates for each of the eight hypothetical gage locations are provided in Table 2. The parameters used for each of the four considered scenarios are described in Table 1. Grid cell class The file "grid_cell_class.tif" contains a model grid cell classification. Model grid cells which were never inundated during the simulation are indicated with 0. Model grid cells which started as ocean water (solid volume fraction of zero) are indicated with 1. Model grid cells which started as landslide material (solid volume fraction greater than zero) are indicated with 2. Finally, model grid cells which started dry but were inundated by water and/or landslide material at some point in the simulation are indicated with 3. Wave arrival time The file "wave_arrival_time.tif" contains the wave arrival time in seconds. The wave arrival time was calculated by analyzing model output at 15 second increments. Simulations were conducted at a 50 m grid resolution. Wave arrival time was defined as the first timestep in which surface levels in a particular grid cell exceeded 1 cm in wave height. If surface levels never exceeded that altitude, or if no water or landslide material ever inundated a particular grid cell, the file indicates "no data". Maximum wave height time The file "maximum_wave_height_time.tif" contains the time of the maximum wave height. The time is given as seconds of simulated time. The maximum surface time was calculated by analyzing model output at 15 second increments and identifying the time when the maximum wave height occurred. Simulations were conducted at a 50 m grid resolution. Model grid cells which were never inundated by water or landslide material are indicated with "no data". Inundated depth The file "inundated_depth.tif" contains the maximum inundation depth for grid cells which started dry, but were inundated at some point in the simulation. These grid cells are identified in "grid_cell_class.tif" with class 3. 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 not classified as class 3 in "grid_cell_class.tif" are indicated with "no data". Simulations were conducted at a 50 m grid resolution. Maximum wave height The file "maximum_wave_height.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. Simulations were conducted at a 50 m grid resolution. Model grid cells which were never inundated by water or landslide material are indicated with "no data". Note that in grid cells which started dry but were inundated, this value does not reflect inundation depth. References Cited Barnhart, K.R., Jones, R.P., George, D.L., Coe, J.A., and Staley, D.M., 2021, 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., https://doi.org/10.3133/ofr20211071. 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 A, 470, 2170, 20130820. 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 A, 470, 2170, 20130819.