| Rose Canyon Fault | |
|---|---|
| Rose Canyon Fault Zone, Newport Inglewood-Rose Canyon Fault Zone, Newport Inglewood-Rose Canyon-Vallecitos-San Miguel Fault Zone, Newport Inglewood-Rose Canyon-Descanso-Agua Blanca Fault Zone | |
 The Rose Canyon Fault is located at the bottom right of the map | |
| Etymology | Rose Canyon |
| Location | Onshore and offshore San Diego |
| Country | United States |
| State | California |
| Characteristics | |
| Part of | California Continental Borderland |
| Length | ~19–106 mi (30–170 km) |
| Tectonics | |
| Plate | Pacific plate |
| Earthquakes | 1862 San Diego earthquake |
| Type | Right-lateralstrike-slip |
TheRose Canyon Fault is a right-lateralstrike-slip fault that runs in a north–south direction off the coast ofSan Diego County, California, until it comes ashore near downtownSan Diego. The fault is linked to theNewport–Inglewood Fault (NIFZ) in the north and either theAgua Blanca Fault orSan Miguel–Vallecitos Fault Zone in the south via en echelonstepovers. Conservative estimates of the fault place the length around 19–31 miles (30–50 kilometers), while interpretations including the NIFZ place the length at 110 mi (170 km). There are not many earthquakes associated with the fault; however, a magnitude 6–6.5 may have struck on the fault in 1862. The fault runs very near to populated areas when offshore; hence, there is high potential for infrequent large and damaging earthquakes.
Southern California lies along atransform boundary between thePacific plate and theNorth American plate. Faulting is taken up by three main groups of faults: theSan Andreas Fault and linked faults, theeastern California shear zone (ECSZ), and theCalifornia Continental Borderland (CCB). The San Andreas system and the ECSZ take up around 85% of the deformation, while the CCB accommodates the rest.[1][2] The CCB is itself split into the Inner (ICB) and Outer Continental Borderlands. The ICB takes up ~0.24–0.31 in (6–8 mm) of the plate boundary's slip, with the Rose Canyon Fault being one of the most hazardous faults in the ICB system.[1][3]
The right-lateralstrike-slip fault extends for 19–31 mi (30–50 km) and slips at a rate of 0.043–0.079 in (1.1–2 mm)/yr.[note 1][4][7] The fault begins inSan Diego Bay, then runs throughLa Jolla before turning offshore. It extends north paralleling the coastline before connecting with theNewport–Inglewood Fault via short en echelonstep overs, and the two faults together extend for 110 mi (170 km).[8][9]
The southern terminus of the Rose Canyon Fault Zone has not been conclusively determined, and is considered to connect to the Descanso and Agua Blanca Faults and/or the San Miguel–Vallecitos Fault Zone.[10][11] Researchers have suggested that both of these faults may transfer slip to the Rose Canyon Fault viaSan Diego Bay step overs, however no clear connection has been determined.[12] Around San Diego Bay, the fault splays out into many different strands, such as the Silver Strand and Spanish Bight faults.[13][14] Some of these splay faults come very close to the Descanso Fault, which in turn links with the Agua Blanca Fault. This leads certain researchers to consider these faults interconnected as one major fault zone, the Newport Inglewood–Rose Canyon–Descanso–Agua Blanca Fault Zone.[10][15][16] Others favor an interpretation which links the Rose Canyon to the San Miguel-Vallecitos Fault Zone, though just like with the Descanso and Agua Blanca faults, there are no visible faults connecting the two.[12] Other researchers attempting to determine which of the two faults the Rose Canyon connects to in the south provide evidence for both faults having a potential link.[17][18][19]
The Rose Canyon Fault has little associated historic seismicity, however a magnitude 6–6.5 earthquake in 1862 is often attributed to it.[20] The shock was assigned aModified Mercalli intensity shaking of VII (Very strong). Shaking was widespread and felt inLos Angeles (over 100 mi (160 km) away). However, due to the lack of reports in the area, it is not possible to guarantee that this earthquake occurred on the Rose Canyon Fault.[21]Trenching of the fault reveals multiple ruptures within the past 8,100 years, including a rupture that occurred between 300 years to shortly before theSan Diego Mission was established.[22] Some of these historic ruptures have an estimated magnitude of 7–7.3.[23]
The Rose Canyon Fault Zone can produce large earthquakes which can be very destructive due to its proximity to major population centers inSouthern California.[8] On the fault, earthquakes nearing magnitude 7 have a recurrence interval between 700±400[24] and 2,000 years.[23] Scenarios modeling a magnitude 6.9 earthquake predictpeak ground acceleration will reach 0.55 g in San Diego, and 0.35 g inTijuana.Downtown San Diego andMission Bay will experienceliquefaction, whileMt. Soledad may experiencelandslides. Coastal areas such as La Jolla andPoint Loma may experience localized coastal bluff failures, and submarine canyons may have landslides which triggertsunamis.[25] Other studies link the Rose Canyon Fault with the Newport-Inglewood, and the combined fault zone can produce M7.3–7.4 earthquakes.[8]
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