#London at risk of major #EARTHQUAKE as new #FaultLines in centre of capital discovered according to the ‘2018 Year’ report

London earthquake: Researchers have found fault lines in the centre of the capital (Image: GETTY )

LONDON could be at risk of a major earthquake after scientists discovered two major fault lines running directly under the capital. Researchers from Imperial College said the fault lines move between 1mm and 2mm a year – running directly under central London and another beneath Canary Wharf.

Dr Richard Ghail, a specialist in civil and environmental engineering at Imperial College, said the chance of a magnitude 5 quake is “enough to be scary”.

The UK experiences hundreds of tremors each year, of which only about 10 are actually felt.

But research shows London and the South East is rising at the rate of 1 to 2mm a year as Britain is squeezed by strong tectonic forces.

In the event of a quake, scientists say the tremors would be similar to that of standing on a platform between two passing trains.

However there is a possibility of structural damage if a magnitude 6 quake strikes.

And today findings by the Imperial College are being used to draw up seismic guidelines for new and renovated builldings in the city, which will be built over the 100 years to withstand a 6.5 magnitude quake.

Dr Ghail said the research had overturned the traditional view of London as geologically stable.

He said: “It now looks a modestly active, very heavily faulted, complicated area.

“It’s probably gone from the simplest to most complex geology in the UK.”

The last time London was hit by a earthquake was back in the 1770s.

But now researchers say there is only a one-in-a-thousand-year chance of a tremor.

Dr Ghail said that although it was “scary” it was “not fundamentally a problem”.

Courtesy of express.co.uk

https://tinyurl.com/y4q8a9wx

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#Satellite images show giant #crack caused by #earthquake in #MojaveDesert, #California, #USA

Before and after images show the epicentre of Friday’s quake. Pic: Planet Labs Inc

The impact of Southern California’s strongest earthquake in 20 years has been revealed after satellite images showed how a huge crack emerged in the Earth’s surface.

The US state was rocked by two powerful earthquakes of magnitudes 7.1 and 6.4 last week along with hundreds of aftershocks.

The stronger quake on Friday struck 11 miles from the city of Ridgecrest, with satellite images by Planet Labs Inc showing the large crack that was ripped open in the Mojave Desert.

Move the slider from left to right to see the difference in images of the epicentre before and after the quake.

The US Geological Survey has reportedly said the crack is not a new fault line and the recent quake activity is not related to the dangerous San Andreas fault.

Before last week, the last time an earthquake above a magnitude of 6 struck Southern California was in 1999 when a 7.1 magnitude event – dubbed the Hector Mine quake – was recorded.

Friday’s quake ruptured gas lines and sparked numerous fires in Ridgecrest, about 125 miles from Los Angeles.

The 6.4 quake caused a fissure near Ridgecrest in the earth last Thursday

Offices in central LA were shaken for around 30 seconds by the tremors, and the quake was also felt in the Hollywood Hills, Las Vegas and parts of Mexico.

It came after Southern California was struck by a 6.4-magnitude quake on Thursday, which was followed by a strong 5.4-magnitude aftershock in the early hours of the next morning.

The force of the earthquake cracked a road Pic: Karaleigh Roe

There were minor injuries but no reports of anyone seriously hurt or killed.

Fears of a large quake had grown recently after 1,000 small tremors were reportedly recorded in Southern California over three weeks.

The “swarmageddon” produced earthquakes with an average magnitude of 3 last month, the LA Times reported.

There have no reports of any fatalities

California officials are spending more than $40m (£32m) on an earthquake early warning system that – in addition to alerting the public – could also be used to automatically halt trains and open fire station doors moments before a major tremor actually strikes.

Emergency management officials have said they intend to have the statewide warning system in place by mid-2021 to serve California’s roughly 40 million residents.

Courtesy of Sky News

https://tinyurl.com/y5zgpfvb

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A SECOND fault line running parallel to San Andreas has just been identified

The San Andreas Fault. Credit: US Geological Survey

Just days after a cluster of more than 200 small earthquakes shook the Salton Sea area of Southern California, scientists have found evidence of a second fault line that runs parallel to the massive San Andreas Fault – one of the state’s most dangerous fault lines.

 

The new fault appears to run right through the 56-km-long Salton Sea in the Colorado Desert, to the west of the San Andreas Fault. Now that we know it’s there, seismologists will be forced to reassess earthquake risk models for the greater Los Angeles area.

 

“This previously unidentified fault represents a new hazard to the region and holds significant implications for fault models … and, consequently, models of ground-motion prediction and southern San Andreas Fault rupture scenarios,” the team from the Scripps Institution of Oceanography and the Nevada Seismological Laboratory reports.

 

Now known as the Salton Trough Fault, the newly mapped fault has been hidden for all this time because it’s submerged beneath the Salton Sea – a vast, salty rift lake that formed as a result of all the tectonic activity in the area.

 

The team had to use an array of instruments, including multi-channel seismic data, ocean-bottom seismometers, and a surveying method called light detection and ranging (LiDAR), to precisely map fault inside several sediment layers both in and surrounding the lakebed.

 

“The location of the fault in the eastern Salton Sea has made imaging it difficult, and there is no associated small seismic events, which is why the fault was not detected earlier,” says Scripps geologist Neal Driscoll.

 

Oddly enough, the fact that we now know there’s an extra fault line running parallel to the San Andreas Fault doesn’t necessarily mean the area is more prone to earthquakes than we originally thought.

 

It might actually solve the mystery of why the region has been experiencing LESS earthquakes than expected.

 

As the team explains, recent research has revealed that the region has experienced magnitude-7 earthquakes roughly every 175 to 200 years for the last 1,000 years. 

 

But that’s not been the case more recently. In fact, a major rupture on the southern portion of the San Andreas Fault has not occurred in the last 300 years, and researchers think the region is long overdue for a major quake.

 

Now they have to figure out what role the Salton Trough Fault could have played in all that.

 

“The extended nature of time since the most recent earthquake on the Southern San Andreas has been puzzling to the earth sciences community,” said one of the Nevada team, seismologist Graham Kent. 

 

“Based on the deformation patterns, this new fault has accommodated some of the strain from the larger San Andreas system, so without having a record of past earthquakes from this new fault, it’s really difficult to determine whether this fault interacts with the southern San Andreas Fault at depth or in time.”

A map of the new fault line, STF. Credit: Sahakian et. al.

On Monday morning, ominous rumblings started to emanate from deep underneath the Salton Sea, and then a ‘swarm’ of small earthquakes – three measuring above magnitude 4 – ruptured at the nearby Bombay Beach.

 

The ruptures continued for roughly 24 hours, with more than 200 small earthquakes having been recorded in the area.

 

These small earthquakes – or temblors – were not very severe, but this is just the third time since records began in 1932 that the area has experienced such an event. And this one had more earthquakes than both the 2001 and 2009 events.

 

The event caused the US Geological Survey to increase the estimated risk of a magnitude 7 or greater earthquake in the next week from to between 1 in 3,000 and 1 in 100. To put that in perspective, without any quake swarms, the average risk for the area sits at around 1 in 6,000.

 

Fortunately, the increased risk now appears to have passed, and according to the Los Angeles Times, California governor’s Office of Emergency Service just announced that the earthquake advisory period is now officially over.

 

Of course, for those living in the area, it’s cold comfort, because the southern San Andreas Fault is still “locked, loaded, and ready to go”. Let’s hope the discovery of the Salton Trough Fault will make it easier for seismologists to at least predict when that will happen.

Courtesy of sciencealert.com

http://tinyurl.com/hbknm9l