Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Skip to content

Try the next-generation Data Catalog at catalog-beta.data.gov and help shape it with your feedback.

Geodetic measurements using a two-color Electronic Distance Meter made in California, 1975 to 2005

Metadata Updated: January 22, 2026

Measurements of changes in the distance (or length) between monuments are provided. These measurements were made using a two-color Electronic Distance Meter (EDM) that can measure distances between 1 and 10 KM. Nominal precision of these data range from 0.3 mm to 1.0 mm dependent upon the baseline’s length. These measurements were made between mid-1975 to mid-2006. Data in this archive are from eight networks, each consisting of more the 9 baselines. The locations of these networks in California include far northwestern California, Hollister, CA., Long Valley Caldera in eastern California, Parkfield, Pearblossom, and Anza; the last two located in Southern California. For four of the networks (Hollister, Parkfield, Long Valley, and Pearblossom), measurements were made roughly once per day with the goal of documenting transient deformation associated with earthquake and/or volcanic areas. Measurements of the other networks were less frequent from a few times each year to annual measurements. In many respects, these data, especially those made daily, are a forerunner of the current method of using GNSS receivers being operated continuously to measure deformation. Some highlights from these data include the following: 1) episodes of inflation of the Long Valley caldera including the energetic episode in late 1997; 2) A 20 year record with high temporal resolution of deformation that proceeded 2004 M6 Parkfield earthquake which includes at least one episode of transient deformation; and 3) A 20-year record of steady rate of strain accumulation over a 10 km long segment of the San Andreas fault in Southern California. The two color EDM is unique amongst EDMs. By ranging on two wavelengths (red and blue), it was able to resolve the correction to the optical travel-time to within 0.1 parts per million (ppm) of the length of the baseline. In contrast, the common single-color EDM require measurements of temperature and pressure at the end points of the baseline and a critical assumption that the temperature and pressure are constant along the baseline. At best, the precision of single color EDMs is 1 ppm. Refined-single color EDM measurements employed an aircraft equipped with temperature and pressure sensors to obtain the profile of these quantities along the baseline.

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

Downloads & Resources

Dates

Metadata Created Date January 12, 2026
Metadata Updated Date January 22, 2026

Metadata Source

Harvested from DOI USGS DCAT-US

Additional Metadata

Resource Type Dataset
Metadata Created Date January 12, 2026
Metadata Updated Date January 22, 2026
Publisher U.S. Geological Survey
Maintainer
Identifier http://datainventory.doi.gov/id/dataset/USGS_65a1646bd34e5af967a3ef79
Data Last Modified 2024-03-15T00:00:00Z
Category geospatial
Public Access Level public
Bureau Code 010:12
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Metadata Catalog ID https://ddi.doi.gov/usgs-data.json
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Datagov Dedupe Retained 20260121204831
Harvest Object Id 8049d6ab-3a41-4bb6-8e39-71e634392fd1
Harvest Source Id 2b80d118-ab3a-48ba-bd93-996bbacefac2
Harvest Source Title DOI USGS DCAT-US
Metadata Type geospatial
Old Spatial {"type": "Polygon", "coordinates": -124.2773, 33.5122, -124.2773, 42.1471, -116.4187, 42.1471, -116.4187, 33.5122, -124.2773, 33.5122}
Source Datajson Identifier True
Source Hash af79b43e04ae789f1e9c154cec672d119f0bee54c3cea6094585d460d0b3194d
Source Schema Version 1.1
Spatial {"type": "Polygon", "coordinates": -124.2773, 33.5122, -124.2773, 42.1471, -116.4187, 42.1471, -116.4187, 33.5122, -124.2773, 33.5122}

Didn't find what you're looking for? Suggest a dataset here.