Nearshore Electrical Resistivity Tomography (ERT) profile data, Ofu, American Samoa, February 2020

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Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: Ferdinand K. Oberle
Originator: Cordell Johnson
Originator: Joshua Logan
Originator: Curt D. Storlazzi
Publication_Date: 2025
Title:
Nearshore Electrical Resistivity Tomography (ERT) profile data, Ofu, American Samoa, February 2020
Geospatial_Data_Presentation_Form: comma-delimited text
Series_Information:
Series_Name: data release
Issue_Identification: doi:10.5066/P1QPSVMZ
Publication_Information:
Publication_Place:
Pacific Coastal and Marine Science Center, Santa Cruz, California
Publisher: U.S. Geological Survey
Other_Citation_Details:
Suggested Citation: Oberle, F.K., Johnson, C., Logan, J.B., Storlazzi, C.D., 2025, USGS Nearshore Electrical Resistivity Tomography (ERT) profile data, Ofu, American Samoa: U.S. Geological Survey data release, https://doi.org/10.5066/P1QPSVMZ.
Online_Linkage: https://doi.org/10.5066/P1QPSVMZ
Online_Linkage:
https://www.sciencebase.gov/catalog/item/67cb2b30d34ed37377098966
Description:
Abstract:
Along-shore surface-based 2D electrical resistivity tomography (ERT) surveys were collected in the nearshore region of Ofu, American Samoa.
Purpose:
Profiles of resistivity on the shoreline will be used to assess the potential for terrestrial groundwater intrusion on the reef and the sources and fate of these water masses.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at: https://cmgds.marine.usgs.gov/fan_info.php?fan=2020-620-FA Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20200130
Ending_Date: 20200205
Currentness_Reference: ground condition at time data were collected
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -169.666836
East_Bounding_Coordinate: -169.657184
North_Bounding_Coordinate: -14.180402
South_Bounding_Coordinate: -14.184693
Keywords:
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: biota
Theme_Keyword: geoscientificInformation
Theme:
Theme_Keyword_Thesaurus: Global Change Master Directory (GCMD)
Theme_Keyword: THERMOCLINE
Theme_Keyword: CORAL REEFS
Theme:
Theme_Keyword_Thesaurus: Data Categories for Marine Planning
Theme_Keyword: Water Column Features
Theme:
Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: time series datasets
Theme_Keyword: electrical resistivity tomography
Theme_Keyword: ERT surveying
Theme_Keyword: resistivity
Theme:
Theme_Keyword_Thesaurus: Marine Realms Information Bank (MRIB) keywords
Theme_Keyword: physical oceanography
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: USGS
Theme_Keyword: Coastal and Marine Hazards and Resources Program
Theme_Keyword: CMHRP
Theme_Keyword: Pacific Coastal and Marine Science Center
Theme_Keyword: PCMSC
Theme:
Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: USGS:67cb2b30d34ed37377098966
Place:
Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: Ofu
Place_Keyword: Papaloloa Point
Place_Keyword: Fatuana Point
Place_Keyword: South Pacific Ocean
Place_Keyword: Territory of American Samoa
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: National Park of American Samoa
Place_Keyword: American Samoa
Place_Keyword: Polynesia region
Access_Constraints:
No restrictions or legal prerequisites for accessing the dataset.
Use_Constraints:
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.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Contact_Person: PCMSC Science Data Coordinator
Contact_Address:
Address_Type: mailing and physical
Address: 2885 Mission Street
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060
Contact_Voice_Telephone: 831-460-4747
Contact_Electronic_Mail_Address: pcmsc_data@usgs.gov
Native_Data_Set_Environment:
Raw data from the resistivity array were processed using the manufacturers software, AGI Earth Imager, on a Dell Personal Computer running Windows 11 Operating System.
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report: No formal attribute accuracy tests were conducted.
Logical_Consistency_Report: Data fall within expected ranges.
Completeness_Report:
Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the metadata for each part of this data release carefully for additional details.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
A formal accuracy assessment of the horizontal positional information in the data set has not been conducted. Latitude and longitude were only measured at the beginning and ending of the ERT transect, and as such, horizontal coordinates are not available at each transect point. However, the transect is a straight line, and the distance of each point along the transect was measured by tape measure. The stated accuracy of the GPS unit used to determine the beginning and ending of the ERT transect is +/- 5m.
Lineage:
Process_Step:
Process_Description:
Surface-based 2D Electrical Resistivity Tomography (ERT) surveys were conducted alongshore at the shoreline for one week in late January and early February of 2020 using a SuperSting R8 (AGI, Austin, Texas, USA) and cable with 56 electrodes at 2-m spacing. A dipole-dipole (DD) array was used with a max n-spacing of 7.
Process_Date: 20240804
Process_Step:
Process_Description:
Resistivity data were processed using the manufacture’s software, AGI Earth Imager, and data exported to comma-delimited text files.
Process_Date: 20241021
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Point
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Geographic:
Latitude_Resolution: 0.00000001
Longitude_Resolution: 0.0000001
Geographic_Coordinate_Units: Decimal degrees
Geodetic_Model:
Horizontal_Datum_Name: D_WGS_1984
Ellipsoid_Name: WGS_1984
Semi-major_Axis: 6378137.0
Denominator_of_Flattening_Ratio: 298.257223563
Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: Table
Entity_Type_Definition:
Comma-delimited table of a vertical profile of the resistivity of soil to electrical conductance. The first row contains column headers.
Entity_Type_Definition_Source: Producer defined
Attribute:
Attribute_Label: Distance_Along_Transect_(m)
Attribute_Definition:
Along-transect distance of vertical resistivity profiles measured from the beginning lat/lon.
Attribute_Definition_Source: Electrode spacing
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 0.0
Range_Domain_Maximum: 110.0
Attribute_Units_of_Measure: meters
Attribute_Measurement_Resolution: 0.1
Attribute:
Attribute_Label: Depth_from_surface_(m)
Attribute_Definition: Depth below ground of resistivity measurement at each probe
Attribute_Definition_Source: Producer defined
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -22.81
Range_Domain_Maximum: 4.0
Attribute_Units_of_Measure: meters
Attribute_Measurement_Resolution: 0.1
Attribute:
Attribute_Label: Resistivity_(ohm m)
Attribute_Definition: Resistivity of soil to electrical conductance
Attribute_Definition_Source: Producer defined
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 0.58
Range_Domain_Maximum: 4127.03
Attribute_Units_of_Measure: Ohm meters
Attribute_Measurement_Resolution: 0.01
Attribute:
Attribute_Label: Latitude_(WGS)
Attribute_Definition:
Latitude in decimal degrees of the beginning and ending of the survey transect line. Empty cells indicate the middle of the survey transect line where no positional data were collected.
Attribute_Definition_Source: Global Positioning System
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -14.18469331
Range_Domain_Maximum: -14.18091509
Attribute_Units_of_Measure: decimal degrees
Attribute_Measurement_Resolution: 0.00000001
Attribute:
Attribute_Label: Longitude_(WGS)
Attribute_Definition:
Longitude in decimal degrees of the beginning and ending of the survey transect line. Empty cells indicate the middle of the survey transect line where no positional data were collected.
Attribute_Definition_Source: Global Positioning System
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -169.6668360
Range_Domain_Maximum: -169.6580912
Attribute_Units_of_Measure: decimal degrees
Attribute_Measurement_Resolution: 0.0000001
Overview_Description:
Entity_and_Attribute_Overview:
The first line of the csv file is a header line. Latitude and longitude were only measured at the beginning and ending of the ERT transect, and as such, horizontal coordinates are not available at each transect point. However, the transect is a straight line, and the distance of each point along the transect was measured by tape measure.
Entity_and_Attribute_Detail_Citation: U.S. Geological Survey
Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey - ScienceBase
Contact_Address:
Address_Type: mailing and physical
Address: Denver Federal Center, Building 810, Mail Stop 302
City: Denver
State_or_Province: CO
Postal_Code: 80225
Contact_Voice_Telephone: 1-888-275-8747
Contact_Electronic_Mail_Address: sciencebase@usgs.gov
Resource_Description:
Two transect lines of resistivity data are available in comma-delimited csv format contained in a single zip file (Ofu20_ERT_Data.zip) accompanied by CSDGM FGDC-compliant metadata.
Distribution_Liability:
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.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: comma-delimited text
Format_Version_Date: 20180818
Format_Information_Content: Zip file contains the csv tables.
File_Decompression_Technique:
Windows users can use WinZIP to uncompress the files; Apple Macintosh users, Archive Utility; Linux and Unix users, gunzip.
Transfer_Size: .03872
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
https://www.sciencebase.gov/catalog/file/get/67cb2b30d34ed37377098966
Network_Resource_Name: https://doi.org/10.5066/P1QPSVMZ
Access_Instructions:
Data can be downloaded using the Network_Resource_Name links. The first link is a direct link to download a zipped file of data and metadata. The second link points to a landing page with metadata and data for the entire data release.
Fees: None.
Technical_Prerequisites: These data can be viewed with any text editor software.
Metadata_Reference_Information:
Metadata_Date: 20250429
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Contact_Person: PCMSC Science Data Coordinator
Contact_Address:
Address_Type: mailing and physical
Address: 2885 Mission Street
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060
Contact_Voice_Telephone: 831-460-4747
Contact_Electronic_Mail_Address: pcmsc_data@usgs.gov
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P1QPSVMZ/Ofu20_ERT_metadata.html>
Generated by mp version 2.9.51 on Thu May 1 13:57:34 2025