Published: Wed, June 22, 2016
Science | By Hubert Green

'Large-scale motion' detected near San Andreas Fault

'Large-scale motion' detected near San Andreas Fault reports researchers identified lobes of uplift and subsidence.

The southern segment of the fault, however, has not experienced a major release of energy since 1857, and the most southerly portion of that southern segment hasn't suffered a major quake since 1690. The researchers added that this Global Positioning System evidence confirmed their earlier prediction.

The GPS array records vertical and horizontal motion of Earth's surface.

Scientists say it's crucial to monitor the San Andreas Fault because of its potential to unleash a catastrophic event on the West Coast.

The San Andreas Fault System in Southern California has detected large-scale motion in the area.

Although the motion was previously predicted in models, it wasn't until now that actual documentation was made.

San Francisco's 1906 natural disaster of magnitude 7.8 left more than half of the city's residents homeless and killed between 700 and 3,000 people.

The new findings were also published on June 20 in Nature Geoscience. Vertical motion is affected by the tectonic motion of the crust, pumping of groundwater, local surface geology and precipitation. Using data collected in this study, geologists will better understand background movements in the fault, which could otherwise be confused with more significant slippage. But the study, which used Global Positioning System data from an observatory that tracks seismic information on the Pacific and North American tectonic plates, will help scientists better understand how the fault line's behavior might affect the region around it. "According to researchers from the University of Hawaii, GPS mapping of the fault line may give researchers a tip as to when the fault is ready to rupture". The northern part of the fault, which ruptured along 300 miles and killed between 700 and 2,800 people in 1906, experienced its most recent notable temblor in the form of the 1989 Loma Prieta quake, which struck during Game 3 of the World Series and, more seriously, injured more than 3,000 people and took the lives of 63. "Consensus is growing, however, of the likelihood of a large and devastating natural disaster to strike California".

A doctoral candidate in the School of Ocean and Earth Science and Technology, Samuel Howell said that the data had been publicly available for over a decade, but the vertical component had been ignored for the most part because of the difficulties that they have in interpreting noisy data.

Howell and his team used a special technique in observing the tectonic motion in order to "break down the noisy signals to isolate a simple vertical motion pattern that curiously straddled the San Andreas fault".

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