Pending earthquake?

[Mike K.]

We've heard it before and we're hearing it again. The likelihood of a major quake is higher than normal due to some sort of activity I don't understand or quite frankly care to understand as theories change on a regular basis.

Anyhow, here's a story from Vic News

(btw, has this already been posted elsewhere on the forum?)

Earthquake scientists detect plate slippage
By Brennan Clarke
Victoria News
Feb 02 2007

Slow-slip tremor began two weeks ago

Local earthquake scientists are paying close attention to an unusual travelling tremor deep inside the earth’s crust.

Called a slow-slip event by some researchers, the tremor began two weeks ago in the Puget Sound area and has since travelled northward along the Juan de Fuca plate at a rate of about 10 kilometres a day.

By Victoria News press time, the tremors, detectable only with high-tech instrumentation, were occurring beneath southern Vancouver Island.

Herb Dragert, a researcher with the Geological Survey of Canada in Victoria, said the wandering tremor is the result of subtle, slow slippage of the Juan de Fuca plate as it pushes against the North American plate in an area known as the Cascadia subduction zone.

A sudden slippage of the two plates would trigger an earthquake similar in magnitude to the one off the coast of Sumatra on Dec. 26, 2004 that killed more than 300,000 people.

But Dragert said the tremors, identified just five years ago, are the result of physiological changes to the basalt rock that comprises the two plates, caused by intense pressure build-up.

“It’s not correct to say the rock is melting, but the mineralogy is changing. There are fluids and volatiles trapped in the rock and they are being expelled,” he said. “It’s a kind of dehydration, you could say it’s being cooked out.”

The materials acts as a kind of lubricant that allows some slippage along the fault line, but that only happens at depth 25 to 45 kilometres below the earth’s surface, where temperatures reach 550-600 Celsius.

The reaction doesn’t happen along part of the fault line closer to the surface because temperatures aren’t hot enough, Dragert said.

Dragert was one of a handful of scientists who, by 2001, had pinpointed subduction zone slippage as the cause of the tremors.

Until recently, scientists believed the two plates were locked together and did not move except in the event of a subduction earthquake.

Tim Melbourne, an associate professor of geophysics at Central Washington University, said that’s what makes the tremors so interesting.

“The reason it’s kind of spooky is we now know that stuff down there is on the move,” he said. “But there’s a big difference between an earthquake and these tremors. With an earthquake, the fault breaks and slips very quickly.”

Since the slow-slip tremors were identified, scientists have determined that they occur at surprisingly regular intervals.

“They happen every 14 to 15 months, plus or minus 45 days,” Dragert said.

But rather than releasing pent-up seismic energy, Dragert said the slow slips actually increase tension, albeit in tiny increments.

The tremors aren’t an indication that a major quake is on the way soon, but Dragert said the chances of a major quake happening increase during one of these tremor episodes.

“We know it adds to the stress, but we don’t know what the breaking point is,” he said. “The tension is creeping up in discreet steps and eventually one these discreet steps will trigger a major quake. We just don’t know when.”

mailto:bclarke@vicnews.com

[Jada]

I just bought a 24 pack of Mr Noodles, just so I could have my fave meal in case of impending doom...

[Dylan Leblanc]

I'm not prepared for an earthquake. Can you share you noodles with me?

[Holden West]

I actually own earthquake insurance. However, I'm not sure what the replacement value is on old IKEA furniture and milk crates. I am concerned about my Hummel figurine collection.

[gumgum]

I just bolted my hutch and armoir to the walls today.
Ya never know.

[Mike K.]

Rule #1: stay away from the Empress until the all quiet alarm rings.

Jada, remember to pack a battery powered water heater. You weren't planning on eating those noodles dry, were you? :smt078

[Icebergalley]

Got to check my survival pack...

Got it in Dec. 1998 after I experienced my first earthquake...

Missed most since..

[zoomer]

Here's an exciting update from the Globe and Mail:

B.C. put on alert for huge quake

JANE ARMSTRONG

From Saturday's Globe and Mail

VANCOUVER — Scientists have alerted British Columbia's emergency-planning department to the possibility of a catastrophic earthquake striking the province's southwest coast next week.

While the probability of a quake is still low, rapid strides in earthquake detection have given federal scientists with the Pacific Geoscience Centre on Vancouver Island greater confidence in their ability to predict when and where one will occur. Garry Rogers, a seismologist at the centre, compared the current earthquake odds to the dangers of driving a car.

“Everyone drives their car every day, and the probability of getting in a car accident is small,” Dr. Rogers said. But during rush hour, the probability of getting into an accident is much higher. “Well, Vancouver Island is now driving in rush hour.”

What prompted the alert was a series of imperceptible tremors emanating from deep beneath the ocean, which scientists now recognize as ominous warnings that the earth is on the move again off Vancouver Island.
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The Globe and Mail

They now estimate the long-awaited giant quake will hit closer to the island's western shoreline than previously thought.

The tremors occurred on what is known as the Cascadia subduction zone, which lies beneath the Pacific Ocean off the West Coast and runs from Vancouver Island to Northern California. The rumblings began last week near Puget Sound near Seattle and made their way north to Vancouver Island in recent days.

The tremors — known in earthquake-speak as an episodic tremor and slip — monitor the ongoing strain between the solid earth on the West Coast and the offshore Juan de Fuca Plate.

The two plates are rubbing against one another, with the offshore plate continually pushing against and under the North American Plate.

The recent tremors mean that even more stress is building between the two, which scientists believe will one day rupture into a major earthquake the size of the one off the coast of Indonesia on Dec. 26, 2004, which killed thousands.

Dr. Rogers said the chances of a major earthquake striking southwestern B.C. spike during the tremor events. The current tremor session is expected to last for another week.

A tremor event is similar to an earthquake, but it occurs at a deep level on a fault where the rocks are hot and elastic.

Instead of the offshore tectonic plates slipping steadily under North America, the scientists now say there are periodic jumps that pass stress up to the more shallow locked section of the fault, where earthquakes occur.

“It's piling [stress] on the upper portion and eventually it will fail,” causing a giant earthquake, Dr. Rogers said.

He offered another analogy to describe the effects of the stress buildup caused by the tremors.

“It's like adding straws to the proverbial camel's back,” he said. “Every time we add a straw, we get closer to failing the camel's back. One of those straws will break the camel's back.”

Scientists at the geoscience centre first discovered the tremor events in 1999. Data showed that seven GPS sites, which were strung along from Vancouver Island to Seattle, were moving out to sea.

It's long been known that Vancouver Island is slowly moving eastward toward the mainland. But suddenly, the data showed the movement was reversed.

Eventually, scientists linked this reversal of movement to the tremor events. Right now, Dr. Rogers noted, Vancouver Island is again moving west.

The scientists' findings were presented four years ago at the annual meeting of the American Geophysical Union in San Francisco.

Since then, dozens of scientists from around the globe have begun tracking tremor events.

One day, one of these tremor events will cause the fault line to rupture, he said, resulting in an earthquake magnitude measuring as high as 9.

It would not be the first great megathrust quake to devastate the West Coast of North America. The geological record on the West Coast has shown that giant earthquakes occur once every 500 years.

The last one struck on Jan. 26, 1700, causing widespread destruction, flooding and a giant tsunami. Indian villages along the coast were wiped out and the tsunami reverberated as far as Japan.

Because B.C.'s West Coast is earthquake territory, the province is more prepared than many jurisdictions. Every B.C. municipality is required by law to have an emergency plan.

Dr. Rogers said a giant quake would cause widespread damage. The rupture line will be about 1,000 kilometres long and the tremors would continue for minutes — not seconds.

The offshore rupture would cause the continental shelf to spring upward, causing a tsunami that would slam the west coast of Vancouver Island, causing property damage and loss of life on coastal communities.

The good news is that West Coast scientists say advances in detecting tremor events have translated into improved methods of pinpointing where the inevitable rupture will occur.

Previously, they could provide a rough location — up to 100 kilometres off Vancouver Island — of the next quake. New data show the quake will occur 25 kilometres closer to shore, meaning the damage will be greater.

As a result of this find, scientists will urge some affected municipalities to toughen their building codes, Dr. Rogers said.

[Jada]

Originally Posted by Derf

Rule #1: stay away from the Empress until the all quiet alarm rings.

Jada, remember to pack a battery powered water heater. You weren't planning on eating those noodles dry, were you? :smt078

Our power was out for four days last december, so we're well stocked on Colman stoves, water bottles, candles and fireworks for entertainment.

[Ben Smith]

A sudden slippage of the two plates would trigger an earthquake similar in magnitude to the one off the coast of Sumatra on Dec. 26, 2004 that killed more than 300,000 people.

The tsunami killed 300,000 people. Not the earthquake. 300,000 people would be the equivalent of wiping out Saanich and a wee bit of Oak Bay. :shock:. I'm going to %$&*ing Nunavet...one safe place left in the world.

[Caramia]

I am so happy right now that I live in Rockland.

[Holden West]

North Fairfield has some of the most dangerously unstable soil in the CRD.

[Galvanized]

EARTHQUAKE LESS LIKELY

Feb 3, 2007

THE LIKELYHOOD OF AN EARTHQUAKE IN OUR AREA HAS GONE DOWN, FOR NOW. THE PACIFIC GEO SCIENCE CENTRE IN SIDNEY SAYS THERE HAS BEEN NO SIGNIFICANT EPISODIC TREMOR AND SLIP ACTIVITY BENEATH SOUTHERN VANCOUVER ISLAND DURING THE PAST 24 HOURS.

SEISMOLOGIST GARY ROGERS SAYS WHILE IT APPEARS THE TREMOR AND SLIPS HAVE STOPPED, THAT DOESN'T MEAN THEY WON'T PICK UP AGAIN IN THE NEXT FEW DAYS. ROGERS SAYS THE PROBABILITY OF AN EARTHQUAKE IN THE NEXT 50 YEARS IS ABOUT TEN PERCENT AND IS MORE LIKELY DURING THE 'ETS' EVENTS.

ROGERS SAYS OVER THE LAST TEN YEARS, THE TREMOR AND SLIP EVENT HAS OCCURED ABOUT EVERY 14 MONTHS.

- NIKKI EWANYSHYN CFAX 1070

[Mike K.]

Phew, well, we've dodged a bullet once again.

Back to the sewage saga.

[Holden West]

Earthquake scientist knows how to shake things up
TOM HAWTHORN meets a man who's got his ear to the ground and translates its tremors to us

TOM HAWTHORN
POSTED ON 07/02/07
Special to The Globe and Mail

VICTORIA -- Garry Rogers does not look at the world the same as the rest of us.

Where we see an Inner Harbour of classic architecture, he sees an area of landfill and soft soils.

Where we admire decorative trim in terra cotta, he is reminded of the laws of gravity.

Where we contemplate the solidity of the earth and speak of being grounded, he knows the terra is far from firma.

Dr. Rogers is a seismologist, a branch of the sciences in which shake, rattle and roll are quantifiable, and not just on the hit parade.

So, when he and his colleagues noted episodic tremors and slip, which they call ETS, along the Cascadia subduction zone, they alerted emergency planners and issued a news release. Just as they'd done twice previously.

This time, however, some media outlets reacted as though Chicken Little and the Boy Who Called Wolf had announced the apocalypse.

The headlines warned of QUAKE FEARS and a HIGHER QUAKE RISK, while noting TSUNAMI COULD HIT OAK BAY HARD. One usually staid journal pronounced: B.C. PUT ON ALERT FOR HUGE QUAKE.

Alarmed citizens called radio stations for further information.

Friends back east telephoned to offer mock farewells.

You would have thought Dr. Rogers was a bearded prophet of doom, a Jeremiah with a seismograph.

As it turned out, the tremors stilled. Reporters moved on in search of the next big story instead of preparing for the Big One.

The unexpected end of the subterranean activity will now be studied by the scientists at the Pacific Geoscience Centre, near Sidney.

As it turns out, the hectic pace of the past few days left the seismologist's office there in disarray. His desktop held mountains of papers, while printed material and rolled posters covered much of the floor. It looked a bit like a backdrop from the theme park ride, "Earthquake: The Big One."

Over all, Dr. Rogers found some headlines to be a tad alarmist, though much of the reporting was accurate. He does not regret the press release.

"As a scientist, what do you do? You inform people," he said.

His office might be messy, but it is relatively safe. Bookcases have been moved to the wall opposite from his desk and are attached to the wall, as are all bookcases in the building.

He hopes last week's warning encouraged Vancouver Island residents to prepare for an earthquake. He maintains water, camping gear and a first-aid kit at home.

He was pleased to note the shopping mall where his teenaged daughter works took last week's warning as an opportunity to remind workers of safety measures.

Lost in the hullabaloo was the exciting science behind the warning.

Much of the time, Vancouver Island is snuggling toward the mainland.

Once in a while, however, it turns around and starts heading for Japan.

These slips, first noted by his colleague Herb Dragert, are recorded thanks to GPS technology. The scientists use satellites to determine what is happening 40-kilometres below our feet.

In 2003, Dr. Rogers and Dr. Dragert published a two-page report in Science about episodic tremor and slip, which has led to a new area of research for earthquake specialists.

"One of the significant things we've done is discovering and explaining this ETS phenomena," Dr. Rogers said. "We've made progress in understanding how the subduction zone -- subduction being the jargon we use for one plate going under another -- activates and builds up stress over time. It's not steady and then it fails. It's episodic. It adds small increments of stress.

"We think it's most likely to fail, or turn into a big earthquake, when one of these increments of stress gets added."

Hence, last week's warning. The next episode of tremors is expected to be recorded in April, 2008.

"You plug away at your research. Sometimes, it's just gradual progress. Other times you discover really neat stuff that has larger implications."

The research leads to better building codes, as well as to the retrofitting of schools and public buildings.

On his morning commute to work along the Pat Bay Highway, he always notes the eight giant bolts that have been added on either side of the Quadra overpass. These make it more structurally sound during an earthquake.

"I think, 'This is good. We're making progress.' " After all, the Big One is inevitable. It had not happened, as of press time.

Born in Vancouver, he earned a science degree at the University of British Columbia, added a masters at the University of Hawaii, then completed a doctorate in geophysics at UBC. His dissertation was titled, "Seismotectonics of B.C."

He had planned on becoming an astronomer until UBC opened a department in geophysics in his second year as an undergraduate.

"I've always been interested in understanding nature and the bigger picture, whether astronomy, biology or earthquakes," he said.

He has worked as an earthquake seismologist for the federal government since Centennial Year (1967). He has written more than 120 articles and research papers, delivered more than 400 public lectures, and has been interviewed more than 3,000 -- make that 3,001 -- times by reporters.

In his 61 years, he has somehow yet to experience a quake of any serious magnitude.

He missed all three of the major events felt on the West Coast in recent years.

He was a newborn when the Valentine's Day earthquake of 1946 struck, was too young to remember the 1949 event, slept through the 1965 quake (after pulling an all-nighter as a student), and found himself on sabbatical with his family in New Zealand when Seattle got a 6.8-magnitude shaking in 2001.

He took a lot of ribbing for the last one. Colleagues teased him about having advance knowledge and fleeing with his loved ones.

We see solid ground and he sees moving tectonic plates. We see stability; he sees "something very dynamic."

"The rest of us see it as something we walk around on that doesn't move. That's why an earthquake is so upsetting."

We see the cheesy disaster movie Earthquake and Dr. Rogers sees "giant tumbling blocks of styrofoam looking like giant tumbling blocks of styrofoam."

Okay, sometimes he does look at the world the same as the rest of us.

[TheVisionary]

Earthquakes huh? Every *edit - at the very least keep your language civilised please*, in existence will eventually happen sooner or later. Whenever, wherever there is ecological, political, environmental, economic, or social unrest, disaster, chaos, instability, distress, and fear, opportunities will abound for those capable and willing to seize the day, or anything else. Carpe Diem (Seize the Day).

Personally, I fear not nor am I overly concerned. When it's time for you to go, you go. That is all.