Earth Changes

California quake model looks for ‘mega-quake’ along Cascadia

King5.com,

10 January, 2013

PORTLAND - New research is giving us some insight into when a major earthquake could strike the Northwest.

The research was done in part by Stanford geophysics Professor Paul Segall. He has been tracking a series of very small tremors that rumble deep within the earth.

The slow tremors happen roughly every summer along the Cascadia Subduction Zone, an undersea fault about 70 miles off the Oregon Coast.

Over the last decade, data shows the tremors have been getting progressively bigger. Last summer, the Pacific Northwest experienced a notably large one.

Experts believe those tremors are adding stress to the offshore fault.

Using this data, Segall built a computer model which suggests it will be one of those tiny quakes that triggers a major magnitude 9 earthquake.

“What we do see is that ultimately one of these tends to develop into a fast and potentially, damaging earthquake,” said Segall.

Segall said that scientists don't yet know how big those tremors need to get before they explode into a mega-thrust quake.

And that means a major earthquake in the Pacific Northwest could still be hundreds of years away.

But, he added, those tiny tremors are a good reminder that we always need to be prepared.

Single Super Quake Could Affect Both Northern, Southern California: Study

Cal EMA will consider amending response plans in light of the new findings, discovered while studying devastating quakes in Asia.

4NBC,

11 January, 2013

For the first time, scientists and emergency planners are examining whether a super quake could affect both Northern and Southern California, rendering the entire state helpless in the aftermath of the "Big One."

Seismologists have warned Southern California that a major quake on the lower San Andreas Fault, the so-called Big One is inevitable. But that the population centers of both Southern and Northern California could be affected simultaneously by one quake on the San Andreas Fault has only recently been recognized as a possibility.

The study by Professor Nadia Lapusta at the California Institute of Technology (Caltech) and Japanese collaborator Hiroyuki Noda focused on explaining the behavior of two devastating quakes in Asia: the 1999 magnitude 7.6 temblor in Taiwan, and the 2011 magnitude 9.0 quake off the eastern coast of Japan.

In both cases, the quake spread across so-called "creeping" fault segments long thought to be incapable of transmitting quakes, according to Caltech Staff Seismologist Kate Hutton, a Lapusta colleague.

"The general idea until this paper was that they would stop a quake," Hutton said.

It was believed the slow, creeping movement prevents stress from building up and keeps such a segment stable, Hutton added.

Lapusta and Noda developed a computer model to explain how under certain conditions "a rupture could just kind of barge right through," Hutton said. "Now the question is how this would apply to California."

Such a creeping zone has been identified in a stretch of the San Andreas Fault in central California, just north of seismically active Parkfield.

The Great San Francisco quake of 1906 occurred on the San Andreas north of the creeping zone. The 1857 Fort Tejon quake occurred to the south. No known quake has ever spanned across that creeping zone.

Whether the model developed by Lapusta and Noda could apply there would depend on local geological variables not yet completely understood, Hutton said.

Responsible for statewide emergency planning and disaster preparedness, California's Emergency Management Agency (Cal EMA) is reviewing the new study, according to spokesman Greg Renick. The agency already has in place a plan for responding to a catastrophic quake in Southern California, and another plan for the San Francisco Bay Area.

Cal EMA anticipates that a catastrophic quake affecting a major population center, much less two, will require response assistance from outside California, and has established procedures in place. Beyond that, Cal-EMA now intends to review the newly published research to see if it exposes any gaps in the current response plans that could be corrected before they’re needed, Renick said.

Every fall, Cal EMA's Golden Guardian program creates a disaster scenario for a multi-agency response drill. The scenario this year involves a catastrophic quake in the San Francisco Bay Area. A magnitude 7.8 temblor on the southern section of the San Andreas was drilled in 2008.

Moderate earthquake at the Mexico / Guatemala coast

In the greater Guatemala Champerico area ( destructive earthquake December 2012).

Why ? Because the distance to Champerico is rather limited and also becuase the earthquake’s epicenter in at approx. the same distance to the coast.

Reported depths are varying very much. USGS reported 90 km and EMSC 60 km, but it looks to be definitively in the deeper layers.

Hypocenters in the deeper layers are making it felt in a wider area but also considerably weaker than shallower quakes.

ER is convinced that this earthqake will NOT generate serious damage or injuries.

Update 17:06 UTC : We expect a max. MMI IV (light shaking) for a wide area around the epicenter. This is a typical subduction earthquake triggered by the Pacific Ocean plate moving (and hanging) below the North American Plate. When the stress becomes to big, an earthquake is generated. USGS reports a Magnitude of M5.1, EMSC M5.1, Geofon M5.3, INSIVUMEH M5.1 and SSN Mexico reports a M5.4 @ 27 km.

SRC	Location	UTC Date/time	M	D	INFORMATION
ER	I Felt A (not Listed) Strong Earthquake	Jan 11 23:59 PM	4.6	0.1	MAP	I Felt It
EMSC	Guatemala	Jan 11 20:32 PM	4.8	238.0	MAP	I Felt It
GEOFON	Mexico-guatemala Border Region	Jan 11 20:32 PM	4.8	236.0	MAP	I Felt It
USGS	Guatemala	Jan 11 20:32 PM	4.9	229.3	MAP	I Felt It
USGS	Offshore Chiapas, Mexico	Jan 11 16:30 PM	5.1	90.4	MAP	I Felt It
EMSC	Offshore Chiapas, Mexico	Jan 11 16:30 PM	5.1	87.0	MAP	I Felt It
GEOFON	Near Coast Of Chiapas, Mexico	Jan 11 16:30 PM	5.3	69.0	MAP	I Felt It
GEOFON	Northern Mid Atlantic Ridge	Jan 11 12:46 PM	4.6	10.0	MAP	I Felt It
EMSC	Northern Mid-atlantic Ridge	Jan 11 12:46 PM	4.6	10.0	MAP	I Felt It
GEOFON	Carlsberg Ridge	Jan 11 12:38 PM	4.6	10.0	MAP	I Felt It
EMSC	Carlsberg Ridge	Jan 11 12:38 PM	4.7	10.0	MAP	I Felt It
USGS	Carlsberg Ridge	Jan 11 12:38 PM	4.7	9.8	MAP	I Felt It
EMSC	Tonga	Jan 11 11:39 AM	4.8	10.0	MAP	I Felt It
GEOFON	Tonga Islands	Jan 11 11:39 AM	4.8	10.0	MAP	I Felt It
EMSC	Fiji Region	Jan 11 09:47 AM	4.8	386.0	MAP	I Felt It
USGS	Fiji Region	Jan 11 09:47 AM	4.8	388.5	MAP	I Felt It
GEOFON	Fiji Islands Region	Jan 11 09:47 AM	4.9	370.0	MAP	I Felt It
EMSC	Andaman Islands, India Region	Jan 11 09:10 AM	5.0	35.0	MAP	I Felt It
USGS	Andaman Islands, India Region	Jan 11 09:10 AM	5.0	34.2	MAP	I Felt It
GEOFON	Andaman Islands, India Region	Jan 11 09:10 AM	4.9	10.0	MAP	I Felt It
EMSC	Off W. Coast Of N. Island, N.z.	Jan 11 05:35 AM	4.6	11.0	MAP	I Felt It
USGS	Off The West Coast Of The North Island Of New	Jan 11 05:35 AM	4.6	11.0	MAP	I Felt It
GEONET	Opunake	Jan 11 05:35 AM	4.6	11.0	MAP	I Felt It
GEOFON	Aegean Sea	Jan 11 00:30 AM	4.6	10.0	MAP	I Felt It

http://earthquake-report.com/2013/01/10/major-earthquakes-list-january-11-2013/