EARTH: Superquakes, supercycles, and global earthquake clustering

The size and type of earthquakes a given fault system may produce remain poorly understood for most major fault systems. Recent superquakes, such as the March 2011 magnitude-9 off Japan and the December 2004 magnitude-9-plus off Sumatra, have been far larger than what most scientists expected those faults to produce. The problem is that current models rely on short historical records, and even shorter instrumental records. Today, scientists are working to rewrite these models based on new paleoseismic and paleotsunami data to create a more comprehensive picture of earthquake activity through time. What they're finding might alarm you.

With short records almost every significant earthquake is "new" to geologists. However, as more data are accumulated, we are beginning to see a more complex record of global strain cycles that may help to predict earthquake behavior in the future. In the January issue of EARTH Magazine, scientists looked at long-term cycling in the northeast Japan Trench and the paleoseismic record in the Cascadia Subduction Zone to try and piece together a clearer picture of earthquake activity in those regions. What will these new data tell us about future earthquakes? Read the story online and find out at http://bit.ly/UyycOp.

Make sure to check out this story and more in the January issue of EARTH Magazine available online now. Learn how long-lost letters shed new light on 19th century Bone Wars; discover how volcanic bubbles build to a burp or a boom; and see how a new map shows Australia's true mineral potential all in this month's issue of EARTH.

Provided by American Geological Institute