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5th December 2014, 05:57 PM
Is the 'big one' coming? Study warns huge 1,000km long fault where megaquake will originate is 'eerily quiet'
Cascadia 'megathrust' fault is a 1,000 Km long dipping fault
It stretches from Northern Vancouver Island to Cape Mendocino California.
Researchers believe fault is 'locked' and pressure building in it.
By MARK PRIGG FOR MAILONLINE
PUBLISHED: 16:05 EST, 4 December 2014 | UPDATED: 11:48 EST, 5 December 2014
The fault zone expected to generate the next 'big one' earthquake has gone silent.
Researchers are baffled by the lack of activity at the 1,00km long Cascadia fault which stretches from Northern Vancouver Island to Cape Mendocino in California.
Experts believe the lack of activity could point to a build up of pressure - which could lead to a massive killer quake.
The Cascadia Subduction Zone (CSZ) 'megathrust' fault is a 1,000 Km long dipping fault that stretches from Northern Vancouver Island to Cape Mendocino California.It separates the Juan de Fuca and North America plates.
THE MEGATHRUST FAULT
The Cascadia Subduction Zone (CSZ) 'megathrust' fault is a 1,000 Km long dipping fault that stretches from Northern Vancouver Island to Cape Mendocino California.
It separates the Juan de Fuca and North America plates.
New Juan de Fuca plate is created offshore along the Juan de Fuca ridge.
The Juan de Fuca plate moves toward, and eventually is shoved beneath, the continent (North American plate).
Two independent research initiatives have both found the same thing - the sound of silence under the sea.
The Cascadia earthquake fault zone 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, and 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.
However, they have detected few signs of the grinding and slipping they expected.
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 told the Seattle pi.
Two teams have been examining the area.
A joint Japanese-Canadian team dropped instruments offshore of Vancouver Island, while Toomey's team 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.
Researchers have been using ships to drop off and later retrieve ocean bottom seismographs - but still say the fault remains 'eerily quiet'.
The Cascadia Initiative (CI) is an onshore/offshore seismic and geodetic experiment that takes advantage of an Amphibious Array to study questions ranging from megathrust earthquakes to volcanic arc structure to the formation, deformation and hydration of the Juan De Fuca and Gorda plates.
Researchers say the area is 'locked'.
The Japanese-Canadian team, which published their research in the Bulletin of the Seismological Society of America, wrote: 'The lack of interplate seismicity is interpreted to reflect complete healing and locking of the megathrust over three centuries after the previous great earthquake,' wrote Koichiro Obana and his co-authors in the BSSA paper.
Experts say this could cause major problem.
'If there were low levels of offshore seismicity, then we could say some strain is being released by the smaller events,' Toomey said.
'If it is completely locked, it means it is increasingly storing energy and that has to be released at some point.'
The Cascadia Initiative (CI) is an onshore/offshore seismic and geodetic experiment that takes advantage of an Amphibious Array to study questions ranging from megathrust earthquakes to volcanic arc structure to the formation, deformation and hydration of the Juan De Fuca and Gorda plates.
Toomey described himself as 'very concerned' and said it is 'imperative' people in the Northwest continue to prepare for a big earthquake.
The last full rip of the Cascadia Subduction Zone happened in January 1700.
The exact date and destructive power was determined from buried forests along the Pacific Northwest coast and an 'orphan tsunami' that washed ashore in Japan.
Geologists digging in coastal marshes and offshore canyon bottoms have also found evidence of earlier great earthquakes and tsunamis.
The inferred timeline of those events gives a recurrence interval between Cascadia megaquakes of roughly every 400 to 600 years, reports the Pacific Northwest Seismic Network.
Read more: http://www.dailymail.co.uk/sciencetech/article-2861318/Is-big-one-coming-Study-warns-huge-1-000km-long-fault-megaquake-originate-eerily-quiet.html#ixzz3L4gmGW5J
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Cascadia 'megathrust' fault is a 1,000 Km long dipping fault
It stretches from Northern Vancouver Island to Cape Mendocino California.
Researchers believe fault is 'locked' and pressure building in it.
By MARK PRIGG FOR MAILONLINE
PUBLISHED: 16:05 EST, 4 December 2014 | UPDATED: 11:48 EST, 5 December 2014
The fault zone expected to generate the next 'big one' earthquake has gone silent.
Researchers are baffled by the lack of activity at the 1,00km long Cascadia fault which stretches from Northern Vancouver Island to Cape Mendocino in California.
Experts believe the lack of activity could point to a build up of pressure - which could lead to a massive killer quake.
The Cascadia Subduction Zone (CSZ) 'megathrust' fault is a 1,000 Km long dipping fault that stretches from Northern Vancouver Island to Cape Mendocino California.It separates the Juan de Fuca and North America plates.
THE MEGATHRUST FAULT
The Cascadia Subduction Zone (CSZ) 'megathrust' fault is a 1,000 Km long dipping fault that stretches from Northern Vancouver Island to Cape Mendocino California.
It separates the Juan de Fuca and North America plates.
New Juan de Fuca plate is created offshore along the Juan de Fuca ridge.
The Juan de Fuca plate moves toward, and eventually is shoved beneath, the continent (North American plate).
Two independent research initiatives have both found the same thing - the sound of silence under the sea.
The Cascadia earthquake fault zone 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, and 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.
However, they have detected few signs of the grinding and slipping they expected.
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 told the Seattle pi.
Two teams have been examining the area.
A joint Japanese-Canadian team dropped instruments offshore of Vancouver Island, while Toomey's team 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.
Researchers have been using ships to drop off and later retrieve ocean bottom seismographs - but still say the fault remains 'eerily quiet'.
The Cascadia Initiative (CI) is an onshore/offshore seismic and geodetic experiment that takes advantage of an Amphibious Array to study questions ranging from megathrust earthquakes to volcanic arc structure to the formation, deformation and hydration of the Juan De Fuca and Gorda plates.
Researchers say the area is 'locked'.
The Japanese-Canadian team, which published their research in the Bulletin of the Seismological Society of America, wrote: 'The lack of interplate seismicity is interpreted to reflect complete healing and locking of the megathrust over three centuries after the previous great earthquake,' wrote Koichiro Obana and his co-authors in the BSSA paper.
Experts say this could cause major problem.
'If there were low levels of offshore seismicity, then we could say some strain is being released by the smaller events,' Toomey said.
'If it is completely locked, it means it is increasingly storing energy and that has to be released at some point.'
The Cascadia Initiative (CI) is an onshore/offshore seismic and geodetic experiment that takes advantage of an Amphibious Array to study questions ranging from megathrust earthquakes to volcanic arc structure to the formation, deformation and hydration of the Juan De Fuca and Gorda plates.
Toomey described himself as 'very concerned' and said it is 'imperative' people in the Northwest continue to prepare for a big earthquake.
The last full rip of the Cascadia Subduction Zone happened in January 1700.
The exact date and destructive power was determined from buried forests along the Pacific Northwest coast and an 'orphan tsunami' that washed ashore in Japan.
Geologists digging in coastal marshes and offshore canyon bottoms have also found evidence of earlier great earthquakes and tsunamis.
The inferred timeline of those events gives a recurrence interval between Cascadia megaquakes of roughly every 400 to 600 years, reports the Pacific Northwest Seismic Network.
Read more: http://www.dailymail.co.uk/sciencetech/article-2861318/Is-big-one-coming-Study-warns-huge-1-000km-long-fault-megaquake-originate-eerily-quiet.html#ixzz3L4gmGW5J
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