Development of offset channels across the San Andreas fault

Ouchi, Shunji

doi:10.1016/j.geomorph.2005.04.004

Cited by 20 publications

(30 citation statements)

References 38 publications

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“…Type A deformation corresponds to the situation in which the offset slope is smaller than the chan nel gradient; Type B to the situation in which the two slopes are equal; and Type C when the offset slope exceeds the channel gradient (Ouchi 2005). According to Ouchi (2005), the average value of So/Sc within the range of 1.1-0.9 is con sidered to represent Type B, the value smaller than the range represents Type A, and the larger value Type C. The deformation types of offset channels reported in this study are judged as Type A except for Kitatake (Type C). Upstream aggradation and downstream degradation, which are expected to occur due to the damming ef fect of offset channel (Ouchi 2004), possibly make Type A offset streams relatively easy to ob tain a continuous gradient.…”

Section: Shikoku Islandmentioning

confidence: 99%

“…The development of offset channels seems to be more a complex phenomenon than generally con sidered, and more studies are certainly required from the viewpoints of both tectonic and fluvial processes. With this perspective in mind, I con ducted a series of flume experiments to see the effects of horizontal fault displacement on ex perimental streams (Ouchi 2004), and discussed the development of offset channels crossing the San Andreas fault, California, based on field measured channel course geometry and longitu dinal profiles (Ouchi 2005). This paper examines the characteristics of small offset streams in Japan, through the analysis of planform channel course geometry and longitudinal profiles meas ured in the field.…”

Section: Introductionmentioning

confidence: 99%

“…This paper examines the characteristics of small offset streams in Japan, through the analysis of planform channel course geometry and longitudinal profiles meas ured in the field. Channels exhibiting clear offset associated with strike-slip faulting are usually too small to measure their planform geometry and longitudi nal profiles accurately on available topographic maps, even on large-scale maps such as 1: 5,000; and therefore, the measurements were per formed in the field with the same measuring in strument used in the measurement of offset channels crossing the San Andreas fault (Ouchi 2005). Compared with the remote, semi-arid and relatively flat Carrizo Plain, California, the field condition of Japanese offset streams is awfully bad.…”

Section: Introductionmentioning

confidence: 99%

“…The orientation of a fault line is determined on large-scale topographical maps with the help of the Digital Active Fault Map of Japan (Nakata and Imaizumi 2002), and converted to magnetic orientation for analytical convenience. plan view (channel course geometry), projected longitudinal profile and longitudinal profile along channel, in the same manner as Ouchi (2005). Definition of geometrical properties ( Figure 2) and the method of analysis follow Ouchi (2004) and Ouchi (2005).…”

Section: Introductionmentioning

confidence: 99%

“…plan view (channel course geometry), projected longitudinal profile and longitudinal profile along channel, in the same manner as Ouchi (2005). Definition of geometrical properties ( Figure 2) and the method of analysis follow Ouchi (2004) and Ouchi (2005). An "offset reach" is the reach connecting the upstream and downstream reaches divided by horizontal fault displacement.…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of Small Offset Streams Crossing Strike-Slip Faults in Japan

Ouchi

2006

Geogr. Rev. JPN, Chirigaku Hyoron

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Abstract:Seven small offset streams crossing strike-slip faults in central to south-western Japan, longitudinal profiles and channel course geometry of which were measured in the field , show no correlation between the amount of channel offset (offset length) and drainage area or channel length above the fault. The method to estimate fault slip rates from the relationship be tween offset length and channel length above the fault seems not valid for these offset streams . The angle of deflection, which is the angle between the fault line and the reach connecting reaches divided by fault displacement (offset reach), shows a negative correlation with offset length for the streams of long offset, while no correlation is clear for the streams of short off set. When the channel offset is short and significant channel shift towards the steepest possible course does not occur yet, fault zone width probably controls the deflection angle. The negative correlation for the streams of long offset may reflect the easier channel shift of the streams with shorter offset among them. The deformation types of these offset streams are judged as Type A (offset slope of fault displacement is smaller than channel gradient) except for one as Type C with larger offset slope. Some configurations characteristic to the deformation types still remain in their longitudinal profiles with various degrees of fluvial adjustment. Offset streams seem to be in the repeated process of tectonic deformation and fluvial adjustment as long as the fault ac tivity continues.

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Section: Shikoku Islandmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characteristics of Small Offset Streams Crossing Strike-Slip Faults in Japan

Ouchi

2006

Geogr. Rev. JPN, Chirigaku Hyoron

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Recovering paleoearthquake slip record in a highly dynamic alluvial and tectonic region (Hope Fault, New Zealand) from airborne lidar

et al. 2015

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Knowing the slip amplitudes that large earthquakes produced in prehistorical times is one key to anticipate the magnitude of large forthcoming events. It is long known that the morphology is preserving remnants of paleoearthquake slips in the form of fault-offset landforms. However, the measured offsets that can be attributed to the most recent paleoearthquakes are generally few along a fault, so that they rarely allow recovering the slip distributions and largest slips of these earthquakes. We acquired~1 m resolution airborne lidar data on a 30 km stretch of a fast-slipping strike-slip fault (eastern Hope Fault, New Zealand) located in a region of high alluvial dynamics where landforms are rapidly evolving. Data analysis reveals >200 offset landforms; only 30% allow a good to moderate quality offset measurement. From these good to moderate quality measures, we recover the slip-length distributions and largest slips of the four most recent large paleoearthquakes and find evidence of 4-6 prior events. The record suggests that large earthquake slip recurred in multiples of about 4 m along the 30 km stretch. Although they have larger uncertainties, the more numerous lower-quality offsets that we also measured reveal a similar earthquake slip record. This shows that, although offset landforms are partly degraded in dynamically active landscapes, they store valuable information on paleoearthquake slips. This information might be recovered provided that the morphology is analyzed at high resolution and "continuously" over a significant fault length. Remote lidar data are powerful to perform such analyses.

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Dynamic Ridges and Valleys in a Strike‐Slip Environment

Duvall

Tucker

2015

JGR Earth Surface

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Strike‐slip faults have long been known for characteristic near‐fault landforms such as offset rivers and strike‐parallel valleys. In this study, we use a landscape evolution model to investigate the longer‐term, catchment‐wide landscape response to horizontal fault motion. Our results show that strike‐slip faulting induces a persistent state of disequilibrium in the modeled landscapes brought about by river lengthening along the fault alternating with abrupt shortening due to stream capture. The models also predict that, in some cases, ridges oriented perpendicular to the fault migrate laterally in conjunction with fault motion. We find that ridge migration happens when slip rate is slow enough and/or soil creep and river incision are efficient enough that the landscape can respond to the disequilibrium brought about by strike‐slip motion. Regional rock uplift relative to baselevel also plays a role, as topographic relief is required for ridge migration. In models with faster horizontal slip rates, stronger rocks, or less efficient hillslope transport, ridge mobility is limited or arrested despite the continuance of river lengthening and capture. In these cases, prominent steep, fault‐facing facets form along well‐developed fault valleys. Comparison of landscapes adjacent to fast‐slipping (>30 mm/yr) and slower‐slipping (≤1 mm/yr or less) strike‐slip faults in California, USA, reveals features that are consistent with model predictions. Our results highlight a potential suite of geomorphic signatures that can be used as indicators of horizontal crustal motion and geomorphic processes in strike‐slip settings even after river capture has diminished or erased apparent offset along the fault.

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Development of offset channels across the San Andreas fault

Cited by 20 publications

References 38 publications

Characteristics of Small Offset Streams Crossing Strike-Slip Faults in Japan

Characteristics of Small Offset Streams Crossing Strike-Slip Faults in Japan

Recovering paleoearthquake slip record in a highly dynamic alluvial and tectonic region (Hope Fault, New Zealand) from airborne lidar

Dynamic Ridges and Valleys in a Strike‐Slip Environment

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