San Andreas Transform Fault Zone
Two of these moving plates meet in western California; the boundary between them is the San Andreas fault. The Pacific Plate (on the west). Aerial view of the San Andreas Fault, the juncture of the Pacific and North American plates. See larger image. These cracks may be small and localized or can stretch thousands of miles where tectonic plates meet. Usually, the rocks on. The San Andreas Fault in California marks the boundary between two of valley that marks where the North America plate meets the Pacific plate. on the San Andreas Fault Observatory at Depth(SAFOD) to drill nearly 2 miles ( km) into the fault. [In Photos: The Great San Francisco Earthquake].
But there's plenty of other wildlife to view and enjoy, including some endangered birds like Bell's vireo, the southwestern willow flycatcher. After the San Andreas Fault works its way through the eastern San Gabriels along the Cajon Pass, it then traverses the southern boundary of the mountains as it moves farther east.
In Highland, just outside of San Bernardino, you can observe the fault's handiwork at Plunge Creek, offset by more than meters over time. Several trenches were dug here along the fault, and radiocarbon dating indicates that an earthquake offset the creek sometime between the 15th and 18th centuries. In the Coachella Valley, you can take your earthquake tourism to a whole new level with a jeep tour with Desert Adventures or Covered Wagon Tours.
If it's not too hot out, hoof it and explore the fault on foot at Mission Creek Preserve and Thousand Palms Oasisboth of which are along the fault line. Enjoy the hot mineral springs any season, day or night, at Two Bunch Palms in Desert Hot Springs, whose healing waters are reportedly released from deep beneath the earth's surface by geological activity related to San Andreas.
Boiling mud pots at the Salton Sea Photo: Sandi Hemmerlein The Salton Sea: The Salton Sea usually attracts a certain kind of visitor -- "snow birds" who come for the winter, photographers building their portfolios, and birdwatchers hoping to catch a migration or two.
But for earthquake tourists, there are plenty of signs of the San Andreas Fault here, running along the North Shore and down to Bombay Beach and the State Recreation Area to the east of the sea, where it terminates. The Mendocino triple junction is the northern junction Juan de Fuca, Pacific, and North American plates and the southern junction is the Rivera triple junction Cocos, Pacific, and North American plates. As the North American plate encountered the Pacific plate the relative motion between them caused the convergent boundary along this portion of the margin of North America to evolve into a transform boundary.
The Pacific plate is moving to the northwest relative to the North American plate and the Juan de Fuca and Cocos plates are moving to the southeast as they separate from the Pacific plate along mid-ocean ridges. This relative motion is expressed along the San Andreas transform fault as right-lateral strike-slip offset. The total offset between the Pacific and North American plates since the fault formed is approximately km, but the amount of offset varies along the different segments of the San Andreas and multiple subparallel faults that also accommodate the relative plate motion.
Characteristics of the San Andreas Fault Zone The surface expression of the San Andreas transform fault zone is a right-lateral strike-slip fault. The fault zone is approximately km long and is made up of three major segments, each with characteristic types, magnitudes and frequencies of earthquake activity. These differences are primarily related to differing geometries between the fault trace and plate motions, and the physical properties of the rock formations that the fault passes through.
The southern segment also called the Mojave segment of the fault lies between its southern end at the East Pacific Rise in the Gulf of California and Parkfield, California.
There is a significant northward bend in the fault trace along this segment in the vicinity of Frazier Park. Compression along the fault zone at this bend has resulted in the formation of a group of mountain ranges called the Transverse Ranges.
Infrequent but relatively large earthquakes are characteristic of this segment.
San Andreas Fault
The average recurrence interval for earthquakes on the southern segment is approximately to years. Eleven years later, Lawson discovered that the San Andreas Fault stretched southward into southern California after reviewing the effects of the San Francisco earthquake. Large-scale hundreds of miles lateral movement along the fault was first proposed in a paper by geologists Mason Hill and Thomas Dibblee.
This idea, which was considered radical at the time, has since been vindicated by modern plate tectonics.
Following recorded seismic events in,andscientists predicted that another earthquake should occur in Parkfield in It eventually occurred in Due to the frequency of predictable activity, Parkfield has become one of the most important areas in the world for large earthquake research.plate tectonics
An array of sensors will be installed to record earthquakes that happen near this area. In particular, scientific research performed during the last 23 years has given rise to about 3, publications. Moreover, the risk is currently concentrated on the southern section of the fault, i. According to this study, a massive earthquake on that southern section of the San Andreas fault would result in major damage to the Palm Springs - Indio metropolitan area and other cities in San BernardinoRiverside and Imperial counties in California, and Mexicali Municipality in Baja California.
Older buildings would be especially prone to damage or collapse, as would buildings built on unconsolidated gravel or in coastal areas where water tables are high and thus subject to soil liquefaction.
San Andreas Fault - Wikipedia
The information available suggests that the fault is ready for the next big earthquake but exactly when the triggering will happen and when the earthquake will occur we cannot tell It could be tomorrow or it could be 10 years or more from now. The ability to predict major earthquakes with sufficient precision to warrant increased precautions has remained elusive. That study predicted that a magnitude 7.
Scientists believe quakes on the Cascadia subduction zone may have triggered most of the major quakes on the northern San Andreas within the past 3, years. The evidence also shows the rupture direction going from north to south in each of these time-correlated events.
A Guide to Earthquake Tourism Along the San Andreas Fault
However the San Francisco earthquake seems to have been the exception to this correlation because the plate movement was moved mostly from south to north and it was not preceded by a major quake in the Cascadia zone. List of earthquakes in California The San Andreas Fault has had some notable earthquakes in historic times: Though it is known as the Fort Tejon earthquake, the epicenter is thought to have been located far to the north, just south of Parkfield.
Two deaths were reported.