Journal Express, Knoxville, IA

Community News Network

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
Community News Network
Features
AP Video
Virginia Governor Tours Tornado Aftermath Kerry: No Deal Yet on 7-Day Gaza Truce Kangaroo Goes Missing in Oklahoma Judge Faces Heat Over Offer to Help Migrant Kids Raw: Deadly Tornado Hits Virginia Campground Ohio State Marching Band Chief Fired After Probe Raw: Big Rig Stuck in Illinois Swamp Obama Advisor Skips House Hearing Power to Be Restored After Wash. Wildfire Dempsey: Putin May Light Fire and Lose Control In Case of Fire, Oxygen Masks for Pets Mobile App Gives Tour of Battle of Atlanta Sites Anti-violence Advocate Killed, but Not Silenced. Arizona Prison Chief: Execution Wasn't Botched Calif. Police Investigate Peacock Shooting Death Police: Doctor Who Shot Gunman 'Saved Lives' MN Twins Debut Beer Vending Machine DA: Pa. Doctor Fired Back at Hospital Gunman Raw: Iowa Police Dash Cam Shows Wild Chase Obama Seeks Limits on US Company Mergers Abroad
Facebook
Hyperlocal Search
Premier Guide
Find a business

Walking Fingers
Maps, Menus, Store hours, Coupons, and more...
Premier Guide
Poll

Upon completion and reopening of Third Street, should the City of Knoxville wait to start the next stage of the Streetscape and Infrastructure project until 2015?

Yes
No
     View Results