Drake M. Singleton Daniel S. Brothers Jenna C. Hill Peter J. Haeussler Robert C. Witter 20231014 comma-delimited text data release DOI:10.5066/P924775B Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey https://doi.org/10.5066/P924775B Drake M. Singleton Daniel S. Brothers Jenna C. Hill Peter J. Haeussler Robert C. Witter 2023 2.0 data release DOI:10.5066/P924775B Pacific Coastal and Marine Science Center, Santa Cruz, CA U.S. Geological Survey Suggested Citation: Singleton, D.M., Brothers, D.S., Hill, J.C., Haeussler, P.J., and Witter, R.C., 2023, Coordinates of percussion driven gravity cores collected in Alaskan lakes and fjords following the 2018 Anchorage earthquake (ver. 2.0, October 2023): U.S. Geological Survey data release, https://doi.org/10.5066/P924775B. https://doi.org/10.5066/P924775B This dataset includes deposit thickness and grain size measurements from sediment cores collected from lacustrine and fjord basins in southcentral Alaska following the 2018 Anchorage earthquake. The cores were collected with a percussion driven gravity corer for use in regional hazard assessments relating to Alaska’s seismic hazard. Identification of fault-related submarine hazards is a primary mission of the USGS Coastal and Marine Hazards and Resources Program. Intraslab earthquakes, which occur at depth within the subducting plate, can cause intense shaking at the Earth’s surface, but do not cause surficial faulting or result in significant land level changes. The seismic shaking associated with intraslab earthquakes can remobilize subaqueous sediment and lead to gravity driven sediment flows, potentially creating a record of past shaking from these events. To gain a better understanding of the conditions that produce seismically triggered deposits in subaqueous basins the USGS collected Chirp seismic and sediment cores from several lakes and fjords following the M7.1 2018 Anchorage earthquake. These data are intended to further our understand of geologic hazard in southcentral Alaska, improve risk assessments for local communities and critical infrastructure, and to provide data for future research on regional paleoseismic records in southcentral Alaska. Additional information about the field activities from which these data were derived is available online at: https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-612-FA https://cmgds.marine.usgs.gov/fan_info.php?fan=2020-615-FA https://cmgds.marine.usgs.gov/fan_info.php?fan=2020-625-FA Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 20200808 20210622 Ground conditions at time data were collected In work As needed -151.490850 -148.537050 62.520180 60.071108 USGS Metadata Identifier USGS:7dfad99c-741f-4dc5-b5d1-e25582ba719a ISO 19115 Topic Category inlandWaters oceans geoscientificInformation Data Categories for Marine Planning substrate USGS Thesaurus core analysis Marine Realms Information Bank (MRIB) keywords sediment None U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP Pacific Coastal and Marine Science Center PCMSC Geographic Names Information System (GNIS) Pacific Ocean Prince William Sound Passage Canal State of Alaska Skilak Lake Kenai Lake Tustumena Lake Chelatna Lake None Harriman Fjord None USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data. U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Microsoft Excel (v 16.6) Caroline A. Schneider Wayne S. Rasband Kevin W. Eliceiri. 2012 Schneider, Caroline A., Rasband, Wayne S., and Eliceiri, Kevin W. "NIH Image to ImageJ: 25 years of image analysis." Nature methods 9.7 (2012): 671-675. https://doi.org/10.1038/nmeth.2089 Quality control of attribute accuracy was conducted during field data collection and processing workflows. Data received review from USGS scientists collecting and processing the data at the end of each workday. Dataset will be updated as cores are processed through the Sediment Core Lab at the Pacific Coastal and Marine Science Center. Users are advised to read the rest of the metadata record carefully for additional details. Cores were collected using a UWITEC percussion driven hammer core during U.S. Geological Survey cruises 2021-612-FA, 2020-615-FA, 2020-625-FA. The cores were transported back to the USGS Pacific Coastal and Marine Science Center core lab for subsequent analyses. 20210622 Event deposits, defined here as deposits with anomalous character relative to background sediments (and interpreted as turbidites), are identified based mainly on thickness (> ~1 cm) and grain size (coarser), and were sampled for grain-size analysis at 3-mm intervals. Event deposit thicknesses were measured in CT images with the ImageJ software package (Schneider et al., 2012), and for deposits with angular contacts, thicknesses were measured perpendicular to the contact. Errors in turbidite thickness are assigned the CT-scan resolution rounded up to the nearest tenth of a millimeter (i.e., 0.1 mm). 20211030 Point Point 81 0.00001 0.00001 Decimal Degrees WGS 1984 WGS 84 6378137.0 298.257224 2021-612_2020-625_2020-615_Event_Deposit_Characteristics.csv Comma-delimited text file containing event deposit thickness and grain size data from core samples. producer defined Core ID Location name, year collected, and core ID (for example, SK20-01A is Skilak Lake 2020 core 01A) U.S. Geological Survey Unique identifier for the sample used given in the field Distance to delta (km) Distance between core location and primary fluvial source. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 0.45 21.3 km (kilometers) 0.1 Sk1 2018 EQ thickness (mm) Measured thickness of the Sk1 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 1.0 17.0 mm (millimeters) 0.1 Sk2 2016 EQ thickness (mm) Measured thickness of the Sk2 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 1.0 26.0 mm (millimeters) 0.1 Sk3 2009 FL thickness (mm) Measured thickness of the Sk3 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 3.5 14 mm (millimeters) 0.1 Sk4 1995 FL thickness (mm) Measured thickness of the Sk4 1995 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 3.0 10.0 mm (millimeters) 0.01 Sk4 1997 FL thickness (mm) Measured thickness of the Sk4 1997 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 1.32 14.0 mm (millimeters) 0.01 Sk5 1964 EQ thickness (mm) Measured thickness of the Sk5 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 12.0 790.0 mm (millimeters) 0.1 Sk6 1954 EQ thickness (mm) Measured thickness of the Sk6 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 18.0 61.5 mm (millimeters) 0.1 Thickness error (mm) Error on the measured thickness of event deposit. Errors in event deposit thickness are assigned the CT-scan resolution rounded up to the nearest tenth of a millimeter (i.e., 0.1 mm). producer defined 0.1 0.1 mm (millimeters) 0.1 2018/1964 Ratio Ratio of Sk1 (2018) measured thickness relative to Sk5 (1964) measured thickness. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 0.0063 0.2308 0.001 2016/1964 Ratio Ratio of Sk2 (2016) measured thickness relative to Sk5 (1964) measured thickness. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 0.0065 0.2068 0.001 Sk1 Basal D80 (microm) The D80 value of the basal sample from event deposit Sk1. The D80 statistic is a measure of grain size fractionation and indicates the grain size diameter that 80-volume percent of the sample is smaller than. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 8.373 176.77 micrometers 0.001 Sk1 Basal sorting (microm) The sorting value of the basal sample from event deposit Sk1. The sorting statistic is a measure of grain size range and the spread about the mean of the grain size population. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 1.8639 3.1745 micrometers 0.0001 Sk2 Basal D80 (microm) The D80 value of the basal sample from event deposit Sk2. The D80 statistic is a measure of grain size fractionation and indicates the grain size diameter that 80-volume percent of the sample is smaller than. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 9.618 307.786 micrometers 0.001 Sk2 Basal sorting (microm) The sorting value of the basal sample from event deposit Sk2. The sorting statistic is a measure of grain size range and the spread about the mean of the grain size population. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 1.644 5.9833 micrometers 0.0001 Sk3 Basal D80 (microm) The D80 value of the basal sample from event deposit Sk3. The D80 statistic is a measure of grain size fractionation and indicates the grain size diameter that 80-volume percent of the sample is smaller than. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 6.8012 14.57 micrometers 0.0001 Sk3 Basal sorting (microm) The sorting value of the basal sample from event deposit Sk3. The sorting statistic is a measure of grain size range and the spread about the mean of the grain size population. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 2.048 2.3337 micrometers 0.0001 Sk5 Basal D80 (microm) The D80 value of the basal sample from event deposit Sk5. The D80 statistic is a measure of grain size fractionation and indicates the grain size diameter that 80-volume percent of the sample is smaller than. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 38.4733 466.5165 micrometers 0.0001 Sk5 Basal sorting (microm) The sorting value of the basal sample from event deposit Sk5. The sorting statistic is a measure of grain size range and the spread about the mean of the grain size population. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 1.4532 15.6086 micrometers 0.0001 Sk6 Basal D80 (microm) The D80 value of the basal sample from event deposit Sk6. The D80 statistic is a measure of grain size fractionation and indicates the grain size diameter that 80-volume percent of the sample is smaller than. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 8.3732 189.4646 micrometers 0.0001 Sk6 Basal sorting (microm) The sorting value of the basal sample from event deposit Sk6. The sorting statistic is a measure of grain size range and the spread about the mean of the grain size population. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 2.3190 10.0257 micrometers 0.0001 Tu1 2016 EQ thickness (mm) Measured thickness of the Tu1 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 5.1 91.6 mm (millimeters) 0.1 Tu2 1995 FL thickness (mm) Measured thickness of the Tu2 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 3.6 14.1 mm (millimeters) 0.1 Tu3 1964 EQ thickness (mm) Measured thickness of the Tu3 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 20.1 538.4 mm (millimeters) 0.1 Tu1 Basal D80 (microm) The D80 value of the basal sample from event deposit Tu1. The D80 statistic is a measure of grain size fractionation and indicates the grain size diameter that 80-volume percent of the sample is smaller than. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 38.4733 38.4733 micrometers 0.0001 Tu1 Basal sorting (microm) The sorting value of the basal sample from event deposit Tu1. The sorting statistic is a measure of grain size range and the spread about the mean of the grain size population. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 3.4024 3.4024 micrometers 0.0001 PC1 (HF0) 2018 EQ thickness (mm) Measured thickness of the PC1 (or HF0) event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 3 23 mm (millimeters) 1 PC1 Basal D80 (microm) The D80 value of the basal sample from event deposit PC1. The D80 statistic is a measure of grain size fractionation and indicates the grain size diameter that 80-volume percent of the sample is smaller than. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 535.8867 535.8867 micrometers 0.0001 PC1 Basal sorting (microm) The sorting value of the basal sample from event deposit PC1. The sorting statistic is a measure of grain size range and the spread about the mean of the grain size population. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 1.9196 1.9196 micrometers 0.0001 Ch1 2018 EQ thickness (mm) Measured thickness of the Ch1 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 1.4 159.0 mm (millimeters) 0.1 Ch2 1991 EQ thickness (mm) Measured thickness of the Ch2 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 1.6 144.3 mm (millimeters) 0.1 Ch3 1964 EQ thickness (mm) Measured thickness of the Ch3 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 1.7 117.3 mm (millimeters) 0.1 Ch7 ~1890s FL thickness (mm) Measured thickness of the Ch7 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 3.4 18.5 mm (millimeters) 0.1 Ch1 Basal D80 (microm) The D80 value of the basal sample from event deposit Ch1. The D80 statistic is a measure of grain size fractionation and indicates the grain size diameter that 80-volume percent of the sample is smaller than. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 50.765 50.765 micrometers 0.001 Ch1 Basal sorting (microm) The sorting value of the basal sample from event deposit Ch1. The sorting statistic is a measure of grain size range and the spread about the mean of the grain size population. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 7.6582 7.6582 micrometers 0.0001 Ch7 Basal D80 (microm) The D80 value of the basal sample from event deposit Ch7. The D80 statistic is a measure of grain size fractionation and indicates the grain size diameter that 80-volume percent of the sample is smaller than. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 15.625 15.625 micrometers 0.001 Ch7 Basal sorting (microm) The sorting value of the basal sample from event deposit Ch7. The sorting statistic is a measure of grain size range and the spread about the mean of the grain size population. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 4.2087 4.2087 micrometers 0.0001 Ke1 1964 EQ thickness (mm) Measured thickness of the Ke1 event deposit. Fields marked -9999 represent either 'no data' areas based on insufficient observations or lack of reliable data, or blank cells/no values. producer defined 12.5 346.0 mm (millimeters) 0.1 Cumulative Turbidite Thickness (mm) Sum of event deposit thickness for each individual event deposit observed in more than ten cores. Values are reported in millimeters followed by the specific deposit name in parentheses. Fields marked NaN represent blank cell/no value. producer defined 137.6 6049.5 mm (millimeters) 0.1 The first line of the csv file is a header line. Location information for each sediment core can be found in the 2021_612_2020_625_2020_615_core_nav shapefile included in this data release. U.S. Geological Survey U.S. Geological Survey - CMGDS mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Event deposit characteristics and grain size data are provided in a comma-delimited text file (2021-612_2020-625_2020-615_Event_Deposit_Characteristics.csv) accompanied by CSDGM FGDC-compliant metadata. Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. comma-delimited text 2016 Comma-delimited text file of event deposit characteristics and grain size data. 0.019 https://doi.org/10.5066/P924775B Data can be downloaded using the Network_Resource_Name link and scrolling to the Environmental Data section. None. Event deposit characteristics and grain size data are in .csv format can be viewed with any standard table editing software (for example, Excel, Numbers). 20231014 U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998