Why are there so many earthquakes in California? Causes, records and predictions – here’s what we know
THE US state of California has once again been hit by an earthquake, its biggest in 20 years.
The 6.4-magnitude epicentre was reported near Searles Valley but no one has been reported dead. But why are there so many earthquakes in California and why do experts predict the state is due a catastrophic quake?
What happened in the 6.4 earthquake?
California was rocked by its biggest earthquake in 20 years as Americans geared up to celebrate Independence Day, on July 4, 2019.
The 6.4-magnitude epicentre was reported near Searles Valley, according to the US Geological Survey (USGS).
Buildings were rocked and some roads were left badly damaged as the quake triggered dozens of emergency calls.
The town of Ridgecrest - 11 miles from the epicentre - saw some building fires break out as it suffered the worst of the damage.
Residents in Las Vegas, some 269 miles from Los Angeles, shared footage of lamps shaking in their homes, as the quake struck.
Aftershocks measuring 4.7, 3.5, 3.8 and 4.2 were recorded, according to officials.
The quake's centre occurred in a remote area, some 125 miles from the centre of Los Angeles, around five miles underground.
While officials are still carrying out checks there does not appear to have been any major structural damage caused.
Some buildings in Ridgecrest suffered some damage though.
What is the San Andreas Fault and where does it run?
California is so prone to earthquakes because it lies on the San Andreas Fault.
The San Andreas Fault extends roughly 800 miles through the US state.
Faults are areas where two tectonic plates come together.
It forms the tectonic boundary between the Pacific Plate and the North American Plate — two subterranean masses that form the bases of the Pacific Ocean and the North American continent.
The fault divides into three segments, each with different characteristics and a different degree of earthquake risk, the most significant being the southern segment, which passes within about 35 miles of Los Angeles.
How many earthquakes have hit California?
There have been around 70 major earthquakes in California since records began in 1812.
However there have been countless tremors and tectonic events in the precariously placed state.
What was the largest earthquake to hit California?
The largest recorded earthquake in California was the 1857 Fort Tejon earthquake, with an estimated magnitude of 7.9.
This earthquake ruptured the San Andreas Fault from Parkfield to Wrightwood, a distance of 225 miles.
The most destructive earthquake to date was the 7.8 magnitude 1906 San Francisco earthquake, which killed over 3,000 people from falling buildings and subsequent fires.
How does the California earthquake warning system work?
Californians get warnings of impending earthquakes through their mobile phones, radios and other devices after state investment in an early detection system.
The ShakeAlert system, which was available to download in January 2019, was created by teams from several universities and could help save lives in the event of a quake.
It uses sensors placed around major towns and cities to detect tremors before they reach urban centres, giving time for an alert to be sent out to the population before the quake arrives.
On Twitter it states: "A ShakeAlert is an early warning from a system that detects significant earthquakes so quickly that alerts can reach many people before shaking arrives."
What is 'the big one'? What do experts predict?
In recent years scientists have claimed the San Andreas fault – located on the so-called Ring of Fire of volcanic activity in the Pacific basin – is overdue a “big one”.
They say a major earthquake will soon strike which could cause widespread devastation, particularly in southern California.
What movies have been made about California earthquakes?
- San Andreas (2015)
- 10.5 (2004) and 10.5: Apocalypse (2006)
- The Great Los Angeles Earthquake (1990)
- Earthquake (1974)
- 10.0 Earthquake (2014)