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Geodimeter measurements and the Southern California uplift

Earthquake Information Bulletin (USGS)
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Abstract

Modern surveying instruments, such as geodimeters, are capable of measuring distances in the range of 1 to 30 kilometers with remarkable precision. Indeed, the present limitation upon the precision of measurement is not the resolution of the instruments themselves but rather the uncertainty introduced by variations in the velocity of light in the atmosphere between the two endpoints of the measured distance. This capability in precise distance measurement can be applied to earthquake studies by using repeated distance measurements to determine changes in the distance between monuments located along the major faults. Such measurements have been made along the San Andreas fault since late 1959, and, as a result, a wealth of data on crustal deformation in that area is now available. In fact, geodimeter measurements of this type furnish a more stable measure of secular strain (change in the ratio of length to length) than any continuously recording strain meter. The superiority of the geodimeter measurement stems principally from the long base line measured which averages over local inhomogeneities (cracks and joints in the rock, inclusions, and so forth).

This article describes the important features of the measurement technique as well as some results for the region of the southern California uplift.  

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Geodimeter measurements and the Southern California uplift
Series title Earthquake Information Bulletin (USGS)
Volume 10
Issue 4
Year Published 1978
Language English
Publisher U.S Geological Survey
Description 5 p.
First page 131
Last page 135
Country United States
State California
Other Geospatial Southern California
Online Only (Y/N) N
Additional Online Files (Y/N) N