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Any parent of a rambunctious youngster can tell you trouble might be afoot when things go quiet in the playroom. Two independent research initiatives indicate there is a comparable situation with the Cascadia earthquake fault zone.
The fault zone expected to generate the next big one lies underwater between 40 and 80 miles offshore of the Pacific Northwest coastline. Earthquake scientists have listening posts along the coast from Vancouver Island to Northern California.
But those onshore seismometers have detected few signs of the grinding and slipping you would expect to see as one tectonic plate dives beneath another, with the exception of the junctions on the north and south ends of what is formally known as the Cascadia Subduction Zone.
It is “a puzzle,” according to University of Oregon geophysics professor Doug Toomey.
“What is extraordinary is that all of Cascadia is quiet. It’s extraordinarily quiet when you compare it to other subduction zones globally,” Toomey said in an interview.
To make sure they’re not missing something, researchers have been using ships to drop off and later retrieve ocean bottom seismographs. These record for up to a year right on top of the fault zone.
A joint Japanese-Canadian team dropped instruments offshore of Vancouver Island. A separate team led by Toomey at the University of Oregon is in its fourth year of deployments. Named the Cascadia Initiative, it is rotating among subduction zone segments offshore of Washington, Oregon and Northern California.
Toomey has skimmed the first three years of his results. The Japanese-Canadian team just published theirs online in the Bulletin of the Seismological Society of America.
The bottom line: Even with more sensitive instruments, it’s still eerily quiet out there. Which leads the researchers to conclude the dangerous Cascadia fault zone is stuck — or in science-speak, it is fully “locked.”
The fault zone expected to generate the next big one lies underwater between 40 and 80 miles offshore of the Pacific Northwest coastline. Earthquake scientists have listening posts along the coast from Vancouver Island to Northern California.
But those onshore seismometers have detected few signs of the grinding and slipping you would expect to see as one tectonic plate dives beneath another, with the exception of the junctions on the north and south ends of what is formally known as the Cascadia Subduction Zone.
It is “a puzzle,” according to University of Oregon geophysics professor Doug Toomey.
“What is extraordinary is that all of Cascadia is quiet. It’s extraordinarily quiet when you compare it to other subduction zones globally,” Toomey said in an interview.
To make sure they’re not missing something, researchers have been using ships to drop off and later retrieve ocean bottom seismographs. These record for up to a year right on top of the fault zone.
A joint Japanese-Canadian team dropped instruments offshore of Vancouver Island. A separate team led by Toomey at the University of Oregon is in its fourth year of deployments. Named the Cascadia Initiative, it is rotating among subduction zone segments offshore of Washington, Oregon and Northern California.
Toomey has skimmed the first three years of his results. The Japanese-Canadian team just published theirs online in the Bulletin of the Seismological Society of America.
The bottom line: Even with more sensitive instruments, it’s still eerily quiet out there. Which leads the researchers to conclude the dangerous Cascadia fault zone is stuck — or in science-speak, it is fully “locked.”
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