Bluefield Daily Telegraph, Bluefield, WV

Sister Newspapers' Blogs

May 8, 2013

When the earth moves under our feet

One of the most breath-taking geologic events is a major earthquake. In just a few moments, shaking of the Earth can result in billions of dollars of damage and thousands of lives lost.

Many earthquakes are related to the movement of tectonic plates, the large chunks of the Earth’s outer surface that move with respect to each other. Plates are “born” in places like Iceland, where magma comes up from below and creates oceanic plate material. Plates “die” where one plate dives beneath another and ultimately is pulled and pushed down so deeply into the Earth it melts away. Plates vary a bit in how fast they move, but about an inch or two a year is not uncommon.

One example regarding tectonic movement is in the Pacific Northwest. The Cascadia subduction zone is the area where the Juan de Fuca plate is diving under the North American plate. The movement generates major earthquakes from time to time. The most recent mega-quake occurred in 1700. Geologists think the region is about due for another similar event.

Recently I was reading in Science News about new information regarding earthquakes and plate movement. In the Cascadia region something called “slow slip” happens about every 15 months. Slow slip occurs when the rocks on either side of a major fault move about the same amount as in a major earthquake, but they do so over weeks to months rather than almost instantaneously.  

The evidence for slow slip was documented first for Cascadia in the bedrock of Vancouver Island, British Columbia. Now that geologists know what to look for, slow slip events have been identified the world around. In Japan, some slow slip events have been documented that occur about each three to five years and last a few months, while others occur more frequently.

Text Only
Sister Newspapers' Blogs
Bill Archer
AP Video
Raw: Massive Dust Storm Covers Phoenix Raw: Bolivian Dancers Attempt to Break Record Raw: Big Rig Stuck in Illinois Swamp Raw: Air Algerie Flight 5017 Wreckage Kerry: No Deal Yet on 7-Day Gaza Truce Raw: Palestinians and Israeli Soldiers Clash Raw: Israel, Palestine Supporters Rally in US 12-hour Cease-fire in Gaza Fighting Begins Judge Faces Heat Over Offer to Help Migrant Kids Kangaroo Goes Missing in Oklahoma More M17 Bodies Return, Sanctions on Russia Grow Gaza Residents Mourn Dead Amid Airstrikes Virginia Governor Tours Tornado Aftermath Raw: Deadly Tornado Hits Virginia Campground Fox Dons 'Bondage Strap' Skirt at Comic-Con Cumberbatch Brings 'Penguins' to Comic-Con Ohio State Marching Band Chief Fired After Probe Raw: Air Algerie Crash Site in Mali Today in History for July 26th Raw: Iowa Police Dash Cam Shows Wild Chase
Greg Jordan