Fault zone structure from topography: Signatures of en echelon fault slip at Mustang Ridge on the San Andreas Fault, Monterey County, California

Abstract

We used high‐resolution topography to quantify the spatial distribution of scarps, linear valleys, topographic sinks, and oversteepened stream channels formed along an extensional step over on the San Andreas Fault (SAF) at Mustang Ridge, California. This location provides detail of both creeping fault landform development and complex fault zone kinematics. Here, the SAF creeps 10–14 mm/yr slower than at locations ∼20 km along the fault in either direction. This spatial change in creep rate is coincident with a series of en echelon oblique‐normal faults that strike obliquely to the SAF and may accommodate the missing deformation. This study presents a suite of analyses that are helpful for proper mapping of faults in locations where high‐resolution topographic data are available. Furthermore, our analyses indicate that two large subsidiary faults near the center of the step over zone appear to carry significant distributed deformation based on their large apparent vertical offsets, the presence of associated sag ponds and fluvial knickpoints, and the observation that they are rotating a segment of the main SAF. Several subsidiary faults in the southeastern portion of Mustang Ridge are likely less active; they have few associated sag ponds and have older scarp morphologic ages and subdued channel knickpoints. Several faults in the northwestern part of Mustang Ridge, though relatively small, are likely also actively accommodating active fault slip based on their young morphologic ages and the presence of associated sag ponds.

Estimation of Recurrence Interval of Large Earthquakes on the Central Longmen Shan Fault Zone Based on Seismic Moment Accumulation/Release Model

“…Although fault creep is found on numerous faults, especially on large-scale strike-slip faults [41], there is lack of detailed study about the R -factor on the Longmen Shan fault zone. In this calculation, the R value of 0.9 is adopted because of more difficulties of creep slip on thrust faults than on strike-slip and normal faults.…”

Applications of airborne and terrestrial laser scanning to paleoseismology

“…Recent ALS campaigns have yielded digital representations of topography at resolutions suffi cient to make measurements of earthquake-related surface deformation (e.g., Hudnut et al, 2002;Bevis et al, 2005;Oskin et al, 2007Oskin et al, , 2010aOskin et al, , 2010bOskin et al, , 2012Prentice et al, 2009;DeLong et al, 2010;Hilley et al, 2010Hilley et al, , 2012. For example, ALS effectively depicts fault trace geometries and stream channels that are offset by structures such as the San Andreas fault (e.g., Arrowsmith and Zielke, 2009;DeLong et al, 2010). Systematic analyses of these data reveal geomorphic features that are barely perceivable in the fi eld, but can fundamentally change our inferences about paleoseismic records and fault segmentation (e.g., Zielke et al, 2010).…”

Characterization of active fault scarps from LiDAR data: a case study from Central Apennines (Italy)

“…Sallenger et al 1999), monitoring of landslides (Dietrich et al 2001, Glenn et al 2006, Ventura et al 2011, measurement of volcanic deformation (Hasegawa et al 2007), identification of faults (Haugerud et al 2003, Sherrod et al 2004, Cunningham et al 2006, Kondo et al 2008, Arrowsmith and Zielke 2009, and estimates of slip rate (Frankel et al 2007). In the last decade, there have been several studies on the geometry of fault scarps using highresolution LiDAR data (Chan et al 2007, Begg and Mouslopoulou 2010, DeLong et al 2010, Hilley et al 2010, Amos et al 2010. However, investigations on the spatial distribution of slope and aspect on active fault scarps, as well as the statistical analysis of these scarp parameters, are still lacking.…”