Several Powerful Earthquakes In the News Today

The earth is obviously trying to shake us off like a dog would it's fleas.

The animation of the world map over the past week is pretty cool. Gives a better idea of when quakes are happening and whther it looks like a connection / pattern.

Is Alaska always that active?

Thanks for posting this, B'net.

Probably mostly due to the increased volcanic activity around the earth's various island chains.

Volcanos errupting in Ethiopia, Indonesia, Trinidad, and Alaska.


I find all this stuff fascinating. If I got a chance to do things over again, I'd certainly want to make a career of earthquake studies. They say these things aren't connected, but watching that animated map of the quakes frequently over the last several decades sure indicates some connection to me. Everything seems to be moving northward in the Pacific Rim area. Watching the animation is a lot like watching the light show in the movie Close Encounters of the Third Kind. One region will have a spatter of quakes and a short time later another another answers with a spatter of their own. Then, along the North American West Coast it is like watching the movie The Blob. It just slowly creeps up and then pounces.

I've seen a lot more activity in the Yellowstone Park area this year too. It is rare to see.

One place we don't hear much about regarding quakes is Canada. I wonder if it is because they just don't have many or because the instruments can't distinguish between earthquakes and glacier movements in the frozen land so they don't monitor it.

There is a Canadian government website I watch to see what is happening there and there are lots of small quakes, but the USGS doesn't map or list any of it. Anyone know why?

Canadian Earthquake Reports and Map

Hmm, found my own answer regarding Canada. It's an old article (posted at the end of this post), but adds interest to the equation. Still doesn't explain why the USGS doesn't map their quake events though.

Here's an article where they raised the alert level of the Pavlof volcano in Alaska today.

http://www.adn.com/front/story/9222647p-9138795c.html


Pavlof Volcano erupts; ash and lava spotted

By TOM KIZZIA
Anchorage Daily News

Published: August 15, 2007
Last Modified: August 15, 2007 at 04:54 PM

Pavlof Volcano on the Alaska Peninsula is erupting, scientists reported this afternoon.

Eyewitnesses on several ships reported seeing incandescent blocks falling down the east-southeast flank of the volcano last night, the Alaska Volcano Observatory reported this afternoon. The observatory had already raised its aviation alert code for the volcano from yellow to orange, and the alert level from advisory to watch, based on heat readings by weather satellites and an escalating swarm of earthquake signals from sensors on the mountain.

A pilot reported a weak ash plume extending five miles southwest of the summit at about 8,400 feet elevation. Scientists said the eruption could become stronger at any time.

Immediate hazards around the volcano include light ashfall on nearby communities, mud flows in local drainages, and lava flows and avalanching of hot debris on the upper reaches of the volcano, the observatory said.

Attention was first drawn to the volcano, 37 miles northeast of Cold Bay, when earthquake activity increased abruptly on Tuesday. Similar patterns of seismicity occurred before eruptions in 1996, 1986, 1983 and 1981, observatory scientists said.

The 1996 eruption resulted in a series of ash explosions, lava-fountaining and lava flows over several months. Ash clouds reached as high as 30,000 feet. An eruption 10 years earlier sent a cloud as high as 49,000 feet. Ash clouds can present a hazard to aviation.

Pavlof is a steep, symmetrical volcano 8,262 feet high. It is one of the most active volcanoes in the Aleutian arc, with nearly 40 historic eruptions.





INDEPTH: FORCES OF NATURE
Earthquakes in Canada: Surviving the moderate ones

CBC News Online | Oct. 12, 2005


Canada is a veritable hotbed of seismic activity. The country averages three to four earthquakes a day ? more than 1,200 a year. The vast majority of them can only be detected by the sensitive equipment that measures seismic activity.

But ? a few times a year ? Canadians do feel the earth move. The most active parts of the country are the western and southwestern regions of British Columbia, including Vancouver Island and the Queen Charlotte Islands, which are struck more than 200 times a year. However, Eastern Canada has also been hit by major quakes, and experts cannot rule out a major earthquake hitting Toronto, Ottawa or Montreal.

Except for reports of one death in an earthquake in Montreal in 1732, nobody has ever been killed by a quake in Canada.

On Nov. 18, 1929, a magnitude 7.2 quake rattled the floor of the Atlantic Ocean about 250 kilometres south of Newfoundland, which was then a British colony. Nobody died from the quake, but 29 drowned after a tsunami swept across the Burin Peninsula.

Date Location Magnitude
June 23, 1946 Vancouver Island 7.3
August 22, 1949 Near Queen Charlotte Islands 8.1
July 10, 1958 Alaska/B.C. border 7.9
June 24, 1970 South of Queen Charlotte Islands 7.4
December 20, 1976 West of Vancouver Island 6.7
February 28, 1979 Yukon/Alaska border 7.2
December 17, 1980 West of Vancouver Island 6.8
December 23, 1985 Mackenzie region, NWT 6.9
November 12, 1988 Saguenay region, Quebec 6.0

The area immediately west of Vancouver is considered one of the most vulnerable in the country. In the Juan de Fuca Strait, two tectonic plates ? the North American Plate and the Juan de Fuca Plate ? rub against each other. The North American Plate is gradually sliding underneath its neighbour, building pressure along the plate boundary.

Eventually, scientists say, this will cause a "subduction earthquake," an incredibly powerful event that could measure up to a magnitude of 9. Based on geological evidence in the region, it's believed that such quakes strike every 300 to 500 years.

Eastern Canada is generally considered to be part of a stable continental region; many small fault lines straddle the Lake Ontario basin and the St. Lawrence River Valley, but the edges of the continental plates ? where most of the world's earthquakes occur ? are thousands of kilometres away.

"The crust is more rigid [in this region]," geologist Arsalan Mohajer of the University of Toronto told CBC News Online. "This is good news and also bad news. The good news is that we don't experience that many earthquakes. The bad news is that we don't know when the next possibly big earthquake will occur, because of a lack of information and data."

The last moderate earthquake in the region occurred on Sept. 25, 1998, when a magnitude 5.4 earthquake, centred just south of Lake Erie, rattled dishes and shook floors across Southern Ontario. A magnitude 5 quake shook the area 12 years earlier, in January 1986.


read more of the article here.