Bokelmann, G.H.R., Kovach, R.L., 2003,
Long-term creep-rate changes and their causes,
GRL, 30, 1445, doi:10.1029/2003GL017012
We discuss measurements of the long-term creep rate from the San
Juan Bautista section of the San Andreas fault. These observations of
aseismic slip span a period of approximately half a century making
it the longest creep record ever measured along an active fault zone.
The records show systematic changes in creep rate over time scales
of tens of years, and we address potential causes of these changes.
In principle, they may be caused either by changes in resistive
forces within the fault
zone or by variations in plate-tectonic driving forces. Such driving
force variations have recently been suggested to have occurred in the
same area (Western North America) and within the same time
window. These should give rise to observable effects in the creep
data, but we find no evidence for temporal changes in plate-tectonic
forcing at these time scales. A natural explanation for the observed
long-term changes is elastic reloading of adjacent locked portions
of the San Andreas fault after large earthquakes and possibly
aseismic strain release that occurs before the earthquakes.
Back to My Homepage , Stanford University or Department of Geophysics