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

Subscribe to Geographical!

geo line break v3

Free eBooks - Geographical Newsletter

Sign up for our weekly newsletter today and get a FREE eBook collection!

geo line break v3

University of Winchester

geo line break v3

EDUCATION PARTNERS

Aberystwyth University University of Greenwich The University of Derby

TRAVEL PARTNERS

Ponant

Silversea

Travel the Unknown

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...

Climate

Marco Magrini looks at the financial pressures spilling out into the…

Geophoto

Few sights are more dramatic than a star-filled sky at…

Polar

A region of Antarctica previously known for relative stability is…

Tectonics

Everything we thought we knew about eruptions could be wrong

Oceans

Sea levels are rising across the globe, but along the…

Polar

Seismometers buried in the Ross Ice Shelf have revealed that…

Wildlife

A tightening of restrictions on the insecticides known as neonicotinoids…

Wildlife

Bonnethead sharks, the second smallest member of the hammerhead family,…

Nature

There’s more than enough plastic in the world. That’s why,…

Wildlife

The recent discovery of more than 200 million termite mounds…

Geophoto

The new year still remains a popular time to set…

Wildlife

After decades battling environmental crises that threaten to rob the…

Climate

As another new year beckons and the fight to protect…

Geophoto

A half century has passed since the ‘Earthrise’ photograph – widely believed to have…

Wildlife

Are howler monkeys being adversely affected by ingestion of pesticides containing…

Tectonics

Why unprepared tourists are putting themselves at risk in order…

Geophoto

The majestic and mighty polar bear is in danger of…

Wildlife

Exciting news for wildlife and photography enthusiasts alike – the…

Wildlife

A new system of robotic aerial vehicles is revolutionising the…

Wildlife

Technology used in creating safe urban environments is now being…