Earthquake cluster spurs questions of another quake soon

Greg Moore
Greg Moore
Rhett Butler
Rhett Butler

By Brooks Baehr - bio | email

MANOA (HawaiiNewsNow) - All the huge earthquakes in recent years have sparked debate. Are they related? Are we seeing an unusual cluster of earthquakes and does it mean another is likely to happen soon in the Pacific Basin that could send a tsunami to Hawaii?

"People have asked," said Greg Moore, Chairman of Geology and Geophysics at the University of Hawaii. "Now that we've had this magnitude 9 earthquake in Japan, is that earthquake itself going to cause other big earthquakes to occur say other places around the pacific?"

Moore and Rhett Butler, a geophysicist and seismologist, are earthquake specialists at the UH. They have answered a lot of questions recently about earthquake clusters.

"In the middle of the last century there were a lot of great earthquakes. And we call a great earthquake, for whatever reason, great earthquakes are 8's and above," Butler told Hawaii News Now.

A 9 magnitude quake rocked Kamchatka in 1952. It was followed by the most violent quake ever recorded, the 9.5 magnitude quake that shook Chile. There was an 8.5 magnitude quake near the Kuril Islands in 1963, a 9.2 magnitude quake in Alaska in 1964, and an 8.7 magnitude quake near Rat Island in the Aleutians in 1965.

"Then following that, for about 35 or 40 years, the rate of great earthquakes dropped off substantially," Butler said.

But in December, 2004 the earth roared again. A 9.1 magnitude earthquake off Sumatra produced a tsunami that killed more than 225,000 people.

Since then there have been several great earthquakes, including the Tonga Trench quake that swamped Samoa in 2009, the February 2010 quake off Chile that measured 8.8 magnitude, and, of course, the recent Japan quake (9.0 magnitude).

Every one of these earthquakes is similar in that each happened because plates on the earth's crust were colliding, building stress that released with an earthquake.

The experts tell us it is very possible the quake along the Japan Trench off Northern Honshu March 11 will increase tension and contribute to another large quake, but only along that same trench within about 250 miles of the March 11 quake.

"When you get to another area around the Pacific, for instance beyond that length, it is probably not going to trigger any kind of big earthquake," Moore said.

"If you are saying, you know, seeing an event in Japan, and that potentially means that there might be an event in another part of the Pacific, that clear relationship has not been established," Butler added.

So why the recent cluster of big quakes? No one can say for sure, but some theorize all the quakes are the norm and that lull from the late 1960's until 2004 was an aberration.

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