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

Will 2019 go down as the year that the world…

Climate

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

Climate

A review of climate crisis coverage in the global media…

Oceans

Marco Magrini looks at the carbon capturing power of the ocean’s…

Oceans

Marine Protected Areas are designed to benefit the marine ecosystem…

Climate

The link between China’s economic growth and increased pollution has…

Climate

An analysis of nine year’s worth of lightning data, covering…

Climate

When getting on ‘board’ with sustainability is the entire goal

Oceans

Many scientists believe that jellyfish numbers are increasing, pointing to…

Geophoto

Prepare to be inspired, startled and filled with awe in…

Climate

Excessive use of nitrogen-based fertilisers is contributing to numerous environmental…

Energy

A group of scientists from Edinburgh University has come up…

Geophoto

​This year’s winning environmental photographs show the impacts of the…

Wildlife

A WWF report has revealed that global forest vertebrate populations…

Climate

Yesterday saw one of the biggest public protest movements in…

Climate

On the eve of millions of world citizens going on…

Wildlife

Around 75 million birds are kept as pets in Indonesia,…

Wildlife

Migratory animals are actively adjusting their traditions to cope with…

Climate

How many trees can you plant in a day?

Polar

New analysis of NASA data has led to the discovery…