May, 2001
This month we go to Explorezone.com to learn about intraslab earthquakes and the potential for this type of earthquake in the Pacific Northwest. Intraslab earthquakes are events that occur within a subducting plate - as opposed to those along the boundary between the subducting and the overlying plate or those within the overlying plate.
Intraslab events are really a special case of intraplate earthquakes. Intraplate is a more general term for earthquakes occuring within a plate, as opposed to between plates. The January 26th, 2001 earthquake in India (the subject of a recent Earth Science in the News) is an example of an intraplate earthquake - but not an intraslab event.
This article was originally published in 1999. It refers to the 1949 Olympia event as an example of an intraslab earthquake. More recently, the Feb 28, 2001 Nisqually earthquake provided another example and highlighted the hazard presented by these types of earthquakes.
Related Web Sites
Earthquake Science: The Explorezone Web site has a brief review of earthquake concepts, including seismic waves, subduction, dip-slip and strike-slip faults, and liquefaction, accompanied by graphics.
Earthquake Hazards in Washington: The site from the Washington Department of Natural Resources has a nice discussion of the tectonics and regional seismicity of Washington state.
The Nisqually Earthquake: This Web site from the University of Washington discusses the February 28, 2001 earthquake. This event is an example of an intraplate - and instraslab - earthquake.
Cascadia Region Earthquake Workgroup: The Cascadia Region Earthquake Workgroup (CREW), a not-for-profit corporation of private and public representatives, maintains this web site to inform the public about earthquake related news in the Pacific Northwest and to improve the ability of Cascadia Region communities to reduce damage from earthquakes.
Related Classroom Activities
Earthquake Activities: The Southern California Integrated GPS Network has developed an educational module on plate tectonics and earthquakes. May be too heavy on text for some students.
Virtual Earthquake: The Virtual Earthquake is an interactive web-based program designed to introduce you to the concepts of how an earthquake epicenter is located and how the Richter magnitude of an earthquake is determined.
Science News Write-Up: Write a report on this article for your class! Here is a suggested outline to help you organize the report.
News Archive
Earth Science News Archive: We are building an archive of these news features. Feel free to browse earlier articles and resources!