Our directory of things of interest

University Directory

Largest deep earthquake puzzles scientists

  • Written by  Harley Rustad
  • Published in Tectonics
The Sea of Okhotsk The Sea of Okhotsk Shutterstock
01 Nov
The strongest deep earthquake ever recorded has puzzled seismologists, as it occurred deeper than was previously thought possible

The magnitude 8.3 earthquake took place 609 kilometres beneath the Sea of Okhotsk between the Kamchatka Peninsula and mainland Russia. It was thought that the extreme pressure at such depths would inhibit the type of rapid fault rupture that caused the quake.

Researchers from the University of California, Santa Cruz compared the quake to the previous largest known deep quake, which took place 637 kilometres beneath Bolivia in 1994. At four kilometres per second, the fault rupture in the Okhotsk quake was much faster than other deep earthquakes.

The researchers suggested that the scale and speed of the Okhotsk event was related to the fact that the subducted Pacific plate is much colder than the subducted slab involved in the Bolivian earthquake. Fluid often acts as a fault lubricant, but at this depth, the pressure should have squeezed the fluid from the slab.

‘If the fault slips just a little, the friction could melt the rock and that could provide the fluid, so you would get a runaway thermal effect. But you still have to get it to start sliding,’ said Thorne Lay, one of the study’s co-authors. ‘Some transformation of mineral forms might give the initial kick, but we can’t directly detect that. We can only say that it looks a lot like a shallow event.’

This story was published in the November 2013 edition of Geographical Magazine

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


Aberystwyth University University of Greenwich The University of Derby




Travel the Unknown


Like longer reads? Try our in-depth dossiers that provide a comprehensive view of each topic


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...


Seismometers buried in the Ross Ice Shelf have revealed that…


A tightening of restrictions on the insecticides known as neonicotinoids…


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


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


The recent discovery of more than 200 million termite mounds…


The new year still remains a popular time to set…


After decades battling environmental crises that threaten to rob the…


As another new year beckons and the fight to protect…


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


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


Why unprepared tourists are putting themselves at risk in order…


The majestic and mighty polar bear is in danger of…


Exciting news for wildlife and photography enthusiasts alike – the…


A new system of robotic aerial vehicles is revolutionising the…


Technology used in creating safe urban environments is now being…


Brazil’s shift to the right of the political spectrum could…


Laura Cole travels to Orkney to find out why numbers…


The unprecedented frequency of winter tick epidemics have resulted in…


Ocean debris, mostly composed of plastic, reaches remote Atlantic islands…


With motion detectors becoming ever more sophisticated, and clearer, crisper…