Geologists have long thought that the central part of California’s famous San Rendress Fleet – about 90 miles (145 km) from San Juan Bautista to Parkfield – is a continuous creeping movement that provides a safe haven.
Dissolution over central San Andreas over the last few decades, so the thinking goes that the likelihood of a major earthquake is low that will break the entire fault from north to south.
New research, however, shows that the movement of the Earth along this central part was not as smooth and stable as previously thought.
Research by two geophysicists at Arizona State University has shown that activity is a sequence of small rod and slip movements – called ‘slow earthquakes’ – that release energy during months.
Although this slow quake did not go unnoticed by the people, experts say they could cause a major catastrophic earthquake in the area around them.
Give the artificial hole radar data researchers from 2003 to 2010 a map of the average rate of mobility for the central section of the San Andres Fult (black line) in the team. Red shows the mobility of the land to the southeast, and blue to the northwest
One such earthquake was the six-magnitude quake that shook Parkfield in 2004.
Mustafa Khoshmanesh, a graduate research assistant at ASU’s School Earth for Earth and Space Exploration (SESE), said:
“Based on current time-independent models, there is a 75 percent chance of an earthquake of magnitude seven or more occurring in northern and southern California over the next 10 years.”
He is the lead author of the Nature Geoscience Paper, which reports on research.
“We have found that the movement on guilt started every one to two years and lasted for several months before closing down,” said Manohar Shirza, assistant professor at SESE and co-author of the paper. Said.
“This epic slow earthquake increases the north-south tension of the central section on the locked parts of the fault,” Shirzai said.
He said the Flinders had two earthquakes of magnitude 7.9 in Fort Tejon in 1857 and 1906 in San Francisco.
Scientists also suggest a method that can cause stop and ongoing movements.
The Central San Andreas Fault (green) is spread by sections (red) that are more active. New research, however, shows that the movement of the Earth along this central part was not as smooth and stable as previously thought.
“Defective rocks have a liquid phase that gets trapped in the gaps between the particles, called pore locations,” said Dr.
‘Periodically compacting the fault materials causes a rapid increase in fluid pressure, which lags the fault and facilitates movement.’
Both scientists used artificial hole radar data from orbit from 2003 to 2010.
These data give them a map of the month-to-month changes in the soil along the central part of the San Andreas Fault.
They combined detailed observations of earth-movement into mathematical models with seismic records.
This model allows them to explore the driving mechanism of slow earthquakes and their link to nearby large earthquakes.
From 2003 to 2010 (bottom scale), defective parts at different distances from Parkfield (left scale) were moved at different rates. When the red movement is above average, the blue shows periods when it was low
D We. “We’ve found that this part of the fault moves an average of three centimeters a year, which is a little over an inch,” Khoshmanesh said.
‘But at some point the movement stops completely, and at other times it has advanced as much as 10 centimeters or about four inches a year.’
A picture of the Central San Andreas Fault emerging from his work suggests that its stick-slip motion is similar to the small timescale of how other parts of the San Rendress Fault run.
They note that the new observation is important because it reveals a new type of fault motion and seismic-induced mechanism that is not considered in current models of seismic hazards used in California.
D Sh. Shirzai said: “Based on our observations, we believe that the seismic crisis in California is something that changes over time and exceeds what people have thought so far.”
He added that an accurate estimate of these various hazards is required to be included in the operational earthquake-forecasting system.
.
