Validation of meter-scale surface faulting offset measurements from high-resolution topographic data

Geosphere
By: , and 

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Abstract

Studies of active fault zones have flourished with the availability of high-resolution topographic data, particularly where airborne light detection and ranging (lidar) and structure from motion (SfM) data sets provide a means to remotely analyze submeter-scale fault geomorphology. To determine surface offset at a point along a strike-slip earthquake rupture, geomorphic features (e.g., stream channels) are measured days to centuries after the event. Analysis of these and cumulatively offset features produces offset distributions for successive earthquakes that are used to understand earthquake rupture behavior. As researchers expand studies to more varied terrain types, climates, and vegetation regimes, there is an increasing need to standardize and uniformly validate measurements of tectonically displaced geomorphic features. A recently compiled catalog of nearly 5000 earthquake offsets across a range of measurement and reporting styles provides insight into quality rating and uncertainty trends from which we formulate best-practice and reporting recommendations for remote studies. In addition, a series of public and beginner-level studies validate the remote methodology for a number of tools and emphasize considerations to enhance measurement accuracy and precision for beginners and professionals. Our investigation revealed that (1) standardizing remote measurement methods and reporting quality rating schemes is essential for the utility and repeatability of fault-offset measurements; (2) measurement discrepancies often involve misinterpretation of the offset geomorphic feature and are a function of the investigator’s experience; (3) comparison of measurements made by a single investigator in different climatic regions reveals systematic differences in measurement uncertainties attributable to variation in feature preservation; (4) measuring more components of a displaced geomorphic landform produces more consistently repeatable estimates of offset; and (5) inadequate understanding of pre-event morphology and post-event modifications represents a greater epistemic limitation than the aleatoric limitations of the measurement process.

 

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Validation of meter-scale surface faulting offset measurements from high-resolution topographic data
Series title Geosphere
DOI 10.1130/GES01197.1
Volume 6
Issue 11
Year Published 2015
Language English
Publisher Geological Society of America
Publisher location Boulder, CO
Contributing office(s) Earthquake Science Center
Description 18 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Geosphere
First page 1884
Last page 1901
Online Only (Y/N) N
Additional Online Files (Y/N) N