Our directory of things of interest

University Directory

Earthquakes trigger seismic activity half the world away

Earthquakes trigger seismic activity half the world away
13 Oct
2018
Major earthquakes are triggering seismic activity half the world away

It is well known that major earthquakes are often followed by aftershocks, sometimes powerful ones. But it is generally understood that these shocks will occur in roughly the same region of the world as the initial quake.

New research reveals a remarkable addition: such shocks are often also observed on the opposite side of the planet. After analysing 44 years of seismic data – from 1973 to 2016 – and comparing it to usual baselines of earthquake frequency, researchers from Oregon State University (OSU) concluded that large earthquakes (of magnitude 6.5 and above) are inducing shocks on the other side of the world.

‘The test cases showed a clearly detectable increase over background rates,’ says Robert O’Malley, researcher in the College of Agricultural Sciences at OSU. ‘Earthquakes are part of a cycle of tectonic stress buildup and release. As fault zones near the end of this seismic cycle, tipping points may be reached and triggering can occur.’ Crucially, the higher the magnitude of the original earthquake, the more likely it is to trigger others. These secondary quakes would generally occur within 30 degrees of the antipodal point of the original epicentre (the point diametrically opposite it) up to three days after the initial event.

The researchers highlight numerous recent examples of this phenomenon in action, including multiple quakes across Asia in the aftermath of the 2010 Chilean earthquake, and high seismic activity on the San Andreas Fault that they have linked to the 2011 Japanese earthquake. These were all apparently triggered by S-waves from the initial quakes thousands of miles away. ‘The understanding of the mechanics of how one earthquake could initiate another while being widely separated in distance and time is still largely speculative,’ explains O’Malley. ‘But irrespective of the specific mechanics involved, evidence shows that triggering does take place, followed by a period of quiescence and recharge.’

This was published in the October 2018 edition of Geographical magazine

geo line break v3

Free eBooks - Geographical Newsletter

Get the best of Geographical delivered straight to your inbox by signing up to our weekly newsletter and get a free collection of eBooks!

geo line break v3

Related items

NEVER MISS A STORY - Follow Geographical on Social

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...

Geophoto

Whatever your subject, looking through a macro lens provides an…

Geophoto

German physicist, biologist and photographer, Andreas Kay was based in…

Geophoto

Prestigious photography competition returns for a third year

Wildlife

 New evidence reveals just how persistent some neonicotinoids are in…

Oceans

Scientists are using underwater loudspeakers to attract fish species back…

Climate

For years, China was the go-to destination for exporting the…

Geophoto

Capturing the perfect shot sometimes means not having the camera…

Energy

New research reveals that the UK needs to act fast…

Wildlife

As Arctic ice diminishes, new pathways are opening up, with…

Climate

As a new decade begins, Marco Magrini wonders if the…

Geophoto

When it comes to shooting a moving subject, most photographers…

Energy

The melting of glaciers over the next 100 years will…

Climate

Large-scale air travel is under public scrutiny, and refusing to…

Climate

For years, China was the go-to destination for exporting the…

Climate

Across the EU, emissions from aviation are increasing and passenger…

Climate

As polluting rich nations court global catastrophe at UN climate…

Climate

Alarmingly, nothing unexpected happened in Madrid

Oceans

The January issue’s dramatic cover image was designed to highlight…

Climate

Protestors from the global south were physically removed yesterday from…

Climate

Climate NGOs point fingers at nations holding back climate crisis…