Active fault
An active fault is a fault that is likely to become the source of another earthquake sometime in the future. Geologists commonly consider faults to be active if there has been movement observed or evidence of seismic activity during the last 10,000 years.[1]
Active faulting is considered to be a
Quaternary faults are those active faults that have been recognized at the surface and which have evidence of movement during the Quaternary Period.[3]
Related
Location
Active faults tend to occur in the vicinity of
Measurement
Various geologic methods are used to define the boundaries of an active fault such as remote sensing and magnetic measurements, as well as other ways. Several types of data, such as seismologic reports or records over time, are used to gauge fault activity. Activity and fault area are correlated, and risk analysis is employed with other factors to determine the potential earthquake hazard.[2]
Geologic conditions in U.S.
The geologic conditions and plate tectonic setting in much of the Western U.S. has resulted in the region being underlain by relatively thin crust and having high heat flow, both of which can favor relatively high deformation rates and active faulting.
In contrast, in the Central and Eastern U.S. (CEUS) the crust is thicker, colder, older, and more stable. Furthermore, the CEUS is thousands of miles from active plate boundaries, so the rates of deformation are low in this region. Nevertheless, the CEUS has had some rather large earthquakes in historical times, including a series of major earthquakes near
References
- ^
"Active fault" (online web page). Earthquake Glossary. USGS Earthquake Hazards Program. November 3, 2009. Retrieved 2011-09-17.
- This article incorporates public domain material from websites or documents of the United States Geological Survey.
- ^ ISBN 978-0-309-07395-0.
- Organizations that authored this book: Geophysics Study Committee, Geophysics Research Forum, National Research Council
- ^ a b
"... relationship between Quaternary faults and earthquakes". Quaternary Faults. USGS Earthquake Hazards Program. October 27, 2009. Archived from the original (online web page) on November 27, 2011. Retrieved 2011-09-17.
- This article incorporates public domain material from websites or documents of the United States Geological Survey.
- ^
"... so many earthquakes and Quaternary faults in the Western U.S." Quaternary Faults. USGS Earthquake Hazards Program. October 27, 2009. Archived from the original (online web page) on November 27, 2011. Retrieved 2011-09-17.
- This article incorporates public domain material from websites or documents of the United States Geological Survey.
External links
- Active faults of New Zealand: an interactive map of active faults near a plate boundary
- The Alquist-Priolo Earthquake Fault Zoning (AP) Act
- Quaternary Fault and Fold Database for the Nation