DOI: 10.5061/dryad.wh70rxx2v
title: Data from: Deformed submarine terraces in Puget Sound, Pacific Northwest indicate only one M &gt; ~7.5 earthquake on the Seattle fault zone in the past 11,000 years

description: Seafloor terraces around ~50 m depth are abundant beneath Puget Sound.
 These terraces have been attributed to a sea-level lowstand ca. 11 ka.
 Depths to the terraces across upper plate faults in Puget Sound can be
 used as a record for tectonic deformation since that time.   The
 data consist of bathymetric and seismic reflection data from Puget Sound,
 Washington, USA. They have been interpreted to show an upward offset in
 bathymetric terraces across the Seattle fault zone. This data repository
 includes the following files necessary to reproduce these results:
 basemap.pdf: Bathymetric and topographic map of the study area (central
 Puget Sound, USA) showing the location of bathymetric profiles and fault
 zones used in the study. bathymetric_datasets.xlsx: Spreadsheet describing
 all public bathymetric datasets used in the study. profiles.zip: Text
 files of bathymetric profiles used in the study. Each profile consists of
 a distance and depth extracted from the bathymetric files listed in
 dataset 2. picks.xlsx: Spreadsheet that identifies each bathymetric
 profile, the x-y coordinate location and measured depth for each
 profile's bathymetric terrace and the uncertainties and propagated
 error for each depth. images.pdf:  PDF document showing locations
 and images for the two seismic reflection profiles used in the study, plus
 explanations for each image. See the Methods section for a description of
 the collection of these profiles.
description: Dataset 5 (images.pdf) shows images from two seismic reflection
 surveys collected in Puget Sound, USA: 2019 CHIRP
 seismic reflection survey This survey was collected by
 the authors in October, 2019 aboard the R/V Weelander, a 15 ft vessel
 operated by the University of Washington School of Oceanography. The
 survey was collected with an ultra-high resolution, 2-16 kHZ Edgetech 216s
 CHIRP system and crossed Elliott Bay, the Duwamish Waterway, and terraces
 offshore Bainbridge Island. Data were processed using a standard CHIRP
 processing workflow that included heave correction and conversion to
 envelope. After processing, the data were collected in an interpretation
 project along with complementary datasets using the IHS Kingdom Suite
 software. Two-way travel time in seconds was converted to depth using a
 constant velocity of 1500 m/s. Depths were not tide-corrected, and we do
 not use absolute depths in this study. 1982 minisparker
 legacy data This survey was collected in 1982 by Dr.
 Mark Holmes and others aboard the R/V Onar at the University of Washington
 School of Oceanography. A cruise map and paper scrolls showing the data
 were produced and were encountered by the authors in the files of the
 University of Washington School of Oceanography. 
description: # Data from: Deformed submarine terraces in Puget Sound, USA indicate only
 one M &gt; ~7.5 earthquake on the Seattle fault zone in the past 11,000
 years Dataset DOI:
 [10.5061/dryad.wh70rxx2v](https://doi.org/10.5061/dryad.wh70rxx2v) ##
 Description of the data and file structure This dataset consists of
 supporting data for the manuscript "Deformed submarine terraces in
 Puget Sound, USA indicate only one M &gt; ~7.5 earthquake on the Seattle
 fault zone in the past 11,000 years." Seafloor terraces around ~50 m
 depth are abundant beneath Puget Sound.  These terraces have been
 attributed to a sea-level lowstand ca. 11 ka. Depths to the terraces
 across upper plate faults in Puget Sound can be used as a record for
 tectonic deformation since that time.   The data consist of bathymetric
 and seismic reflection data from Puget Sound, Washington, USA. They have
 been interpreted to show an upward offset in bathymetric terraces across
 the Seattle fault zone. ### Files and variables #### File:
 bathymetric_datasets.xlsx **Description:**  This spreadsheet lists all of
 the public bathymetric datasets used in this study and includes links to
 each dataset. The datasets are listed in order of use (highest resolution
 on top). The first three rows of the dataset are text descriptions; the
 fourth row are column headers (described below). * *File name:* Name of
 the bathymetric dataset assigned by NOAA * *Grid size:* Size in meters of
 the bathymetric grid.  Most datasets consist of multiple layers with
 different grid sizes covering different depths.  Each layer is a row. *
 *General location:* General description of the dataset location in Puget
 Sound * *Year:* Year of dataset publication * *Vertical datum:* Vertical
 datum that depths are referenced to * *Tide station:* Tide station for the
 vertical datum * *Horizontal datum:* Horizontal reference datum *
 *Projection:* Map projection * *Scale:* Scale of the map * *Full file
 name:* Full file name * *Website:* Hyperlink to dataset ### File:
 basemap.pdf **Description:** This map of central Puget Sound, USA, shows
 locations of the bathymetric profiles used in this study, as well as major
 fault zones. #### File: picks.xlsx **Description:** This spreadsheet
 provides x-y locations for each terrace used in the study, as well as
 measured depths to each terrace. Depth uncertainty is listed and
 calculated for each measurement. Profiles are listed from north to south
 and keyed to the filenames in profiles.zip. The data in each field were
 measured from the associated bathymetric slope profile. All depths are
 measured in meters (m) below mean lower low water (MLLW). The first three
 rows of the dataset are descriptive text; the fourth row are column
 headers (described below). * *North to south index:* Profile index number;
 numbered from north to south, first on the east side of Puget Sound, then
 on the west. * *Terrace index*: Index number for each terrace * *Profile
 file name:* Name of profile file in profiles.zip * *y (NAD83 UTM 10N):*
 UTM coordinates for the back edge of the terrace * *x (NAD83 UTM 10N):*
 UTM coordinates for the back edge of the terrace * *East or west side of
 Puget Sound:* Whether the terrace lies on the east or west side of Puget
 Sound (east/west) * *Location relative to SFZ (zone of mapped faults):*
 Whether the terrace is north of the zone of mapped SFZ faults (north),
 south of the zone of mapped faults (south), within the zone of mapped
 faults (in), or whether publications disagree about whether faults exist
 around the location of the terrace (testable) * *Descriptive
 location:* Brief description of the terrace location with respect to
 onshore landmarks. * *Identifier for which terrace tread is imaged in
 profile, numbered by increasing depth ("2" is the terrace
 studied herein):* Numbers indicating whether the profile shows a terrace
 adjacent to the modern shoreline (1), and/or a terrace around 50 m depth
 (2), or both. * *Environment:* Inferred geologic feature at the terrace,
 inferred from surrounding topography and bathymetry. Only populated for
 notable examples. * *Confidence that there is a terrace (high, med, low):*
 Author's confidence that the profile shows a terrace and not other
 features, only populated for notable examples. * *Comments:* Author's
 comments about the profile or the pick. * *Anomaly?:* Descriptive text if
 pick is anomalous * *Distance from Alki Point (km):* Distance in
 kilometers of the picked terrace back edge from Alki Point. * *Bathymetric
 error (m):* Error of the bathymetric dataset at the picked terrace back
 edge. * *Depth picked at shoreline angle inflection point by EJD (m):*
 Depth in meters of the terrace back edge, picked manually by the author. *
 *Picking error assigned by EJD (m):* Error in meters of the pick location
 assigned by the author. * *Seaward edge of terrace depth (m):* Depth in
 meters of the deepest extent of the terrace * *Depth of base of steeper
 slope above terrace (m):* Depth in meters of the slope above the terrace
 (i.e., the shallowest depth of the terrace) * *Propagated error UP (m):*
 Error in meters of picked terrace depth calculated by formally propagating
 bathymetric error, picking error, and 0.3 m of measurement error in the
 comparative dataset. The terrace inner edge could be at the picked depth
 or as shallow as this value. * *Propagated error DOWN (m):* Error in
 meters of picked terrace depth calculated by formally propagating
 bathymetric error, picking error, up to 3 m of sediment cover, and 0.3 m
 of measurement error in the comparative dataset. The terrace inner edge
 could be at the picked depth or as deep as this value. #### File:
 images.pdf **Description:** This provides images and maps with locations
 of seismic reflection data used in this study. #### File: profiles.zip
 **Description:** This .zip folder includes one text file for each
 bathymetric profile used in the study. The first column is a measured
 distance along the profile (starting at 0 at the landward edge of the
 profile) measured in meters (m); the second column is a depth measured in
 meters (m) below mean lower low water (MLLW).