Creep is steady fault movement, varying from continuous to episodic with creep events lasting minutes to days.
Creep Evidence of Active Faulting
Creep is steady fault movement, varying from continuous to episodic with creep events lasting minutes to days. Generally creep occurs without any associated earthquake activity (i.e., aseismic.) Creep has been monitored on the Hayward fault for fifty years (Lienkaemper et al., 2012) and is also observed along some sections of other faults in the San Francisco Bay region, including the San Andreas, Calaveras, Concord-Green Valley and Maacama (Galehouse and Lienkaemper, 2003).
Deep Creep and Earthquakes
How deep does creep go? How can a creeping Hayward fault still produce major earthquakes? The short answer is that the depth of creep varies, from as little 2 miles deep in northern Oakland to as deep as 7 miles near the northern and southern ends of the fault. Unfortunately, this means the lower, brittle fault zone remains largely locked (i.e., it's not creeping), so it's building strain which can only be relieved by major earthquakes, which occur about every 100 to 200 years. The average recurrence time for earthquakes is determined by paleoseismologists, geologists who work in trenches across the faults. They document evidence of paleoearthquakes recorded in sedimentary layers, using radiocarbon analysis to date them.
For More Information
- Hayward Fault Tour
Includes photos in Fremont, Hayward, Oakland, Berkeley, San Leando, and Point Pinole regions
- SFSU Creep Project
Current alinement array data
- Creepmeters on the Hayward Fault
Creepmeter array and plot of 12 years of creepmeter data
- San Francisco Bay Region Crustal Deformation Measurements
USGS realtime creepmeter data plots
Related Content
Below are publications associated with this project.
Long-term creep rates on the Hayward Fault: Evidence for controls on the size and frequency of large earthquakes
Data from theodolite measurements of creep rates on San Francisco Bay region faults, California
Inferences drawn from two decades of alinement array measurements of creep on faults in the San Francisco Bay Region
Variations in creep rate along the Hayward Fault, California, interpreted as changes in depth of creep
Related Content
- Publications
Below are publications associated with this project.
Long-term creep rates on the Hayward Fault: Evidence for controls on the size and frequency of large earthquakes
The Hayward fault (HF) in California exhibits large (Mw 6.5–7.1) earthquakes with short recurrence times (161±65 yr), probably kept short by a 26%–78% aseismic release rate (including postseismic). Its interseismic release rate varies locally over time, as we infer from many decades of surface creep data. Earliest estimates of creep rate, primarily from infrequent surveys of offset cultural featurAuthorsJames J. Lienkaemper, Forrest S. McFarland, Robert W. Simpson, Roger Bilham, David A. Ponce, John Boatwright, S. John CaskeyData from theodolite measurements of creep rates on San Francisco Bay region faults, California
IntroductionOur purpose is to annually update our creep-data archive on San Francisco Bay region active faults for use by the scientific research community. Earlier data (1979-2001) were reported in Galehouse (2002) and were analyzed and described in detail in a summary report (Galehouse and Lienkaemper, 2003). A complete analysis of our earlier results obtained on the Hayward Fault was presentedAuthorsForrest S. McFarland, James J. Lienkaemper, S. John CaskeyInferences drawn from two decades of alinement array measurements of creep on faults in the San Francisco Bay Region
We summarize over 20 years of monitoring surface creep on faults of the San Andreas system in the San Francisco Bay region using alinement arrays. The San Andreas fault is fully locked at five sites northwest from San Juan Bautista, the southern end of the 1906 earthquake rupture, that is, no creep (< 1 mm/yr) is observed. Likewise, the San Gregorio, Rodgers Creek, and West Napa faults show no creAuthorsJ.S. Galehouse, J. J. LienkaemperVariations in creep rate along the Hayward Fault, California, interpreted as changes in depth of creep
Variations ill surface creep rate along the Hayward fault are modeled as changes in locking depth using 3D boundary elements. Model creep is driven by screw dislocations at 12 km depth under the Hayward and other regional faults. Inferred depth to locking varies along strike from 4-12 km. (12 km implies no locking.) Our models require locked patches under the central Hayward fault, consistent withAuthorsR. W. Simpson, J. J. Lienkaemper, J.S. Galehouse