Abstract
The Ventura Thrust system in California is capable of producing large magnitude earthquakes. Geological studies suggest that the fault geometry is complex, composed of multiple segments at different dips: thrust ramps dipping 30°–50° linked with bed-parallel décollements dipping < 10°. these="" latter="" types="" of="" gently="" dipping="" faults="" form="" due="" to="" preexisting="" weaknesses="" in="" the="" crust,="" and="" therefore="" have="" different="" frictional="" parameters="" from="" thrust="" ramps;="" the="" faults="" also="" experience="" different="" stresses="" because="" of="" how="" stresses="" are="" resolved="" onto="" the="" fault="" planes.="" here,="" we="" use="" a="" two-dimensional="" fault="" model="" to="" assess="" how="" geometry="" and="" frictional="" properties="" of="" the="" ramp/décollement="" system="" should="" affect="" the="" seismic="" cycle.="" we="" test="" velocity-strengthening,="" velocity-weakening,="" and="" conditionally="" stable="" décollements,="" and="" in="" addition="" explore="" how="" the="" dip="" angle="" of="" the="" décollement="" changes="" the="" earthquake="" behavior.="" a="" velocity-strengthening="" décollement="" cannot="" replicate="" the="" through-going="" earthquake="" ruptures="" that="" have="" been="" inferred="" for="" the="" ventura="" fault="" system.="" we="" therefore="" suggest="" that="" this="" and="" other="" décollements="" may="" be="" better="" represented="" using="" a="" velocity-weakening="" or="" conditionally="" stable="" response.="" our="" results="" show="" that="" minor="" variations="" in="" fault="" geometry="" produce="" slip="" amounts="" and="" recurrence="" intervals="" that="" differ="" only="" by="" 10–20%,="" but="" do="" not="" fundamentally="" alter="" the="" types="" of="" earthquakes="" and="" interseismic="" slip.="" we="" conclude="" that="" geological="" constraints="" on="" fault="" geometry="" are="" typically="" sufficient="" to="" produce="" modeled="" earthquake="" sequences="" that="" are="" statistically="" consistent="" with="" paleoseismic="" records.="" however,="" both="" frictional="" parameters="" along="" the="" fault="" and="" effective="" normal="" stress="" influence="" earthquake="" rupture="" patterns="" significantly.="" more="" research="" is="" needed="" to="" adequately="" constrain="" these="" quantities="" in="" order="" for="" earthquake="" rupture="" models="" to="" work="" as="" effective="" predictors="" of="" fault="">