"We think that when Cascadia ruptures, it causes stress that transfers to the San Andreas, and we think that within a few decades this triggers the San Andreas to go off. Timing is not exact; it could be hours, it could be years or it could be decades, but it is pretty close in [geological] time either way."
This fact that major fault systems have relationships with one another is a relatively recent discovery — only known for the last 15 years or so, according to Goldfinger.
"People used to think that fault lines were isolated from one another, but this doesn't make sense anymore," Goldfinger said. "Every piece of the earth is connected, so when one moves it is no longer surprising that the other pieces around it can be affected."
But how can this new knowledge about the West Coast fault lines be utilized?
The research allows scientists to understand the directivity of the two fault lines. For example, San Francisco can be affected very differently by earthquakes depending on whether the fault ruptures from north to south or south to north.
When an earthquake hits the Bay Area and travels from south to north, it has a tendency to move out to sea and therefore cause significantly less damage. However, if the quake goes north to south, San Francisco will be severely shaken.
The research provided by Goldfinger's team indicates that because the northern Cascadia fault triggers the southern San Andreas Fault, there is an increased likelihood that earthquakes will travel north to south, increasing damage.
Studying past earthquakes also gives scientists a geological timeline of when to expect the next one.
The last major earthquake occurring along the entire fault line, a 9 on the Ritcher scale, occurred in 1700.
According to Goldfinger, the northern part of the Cascadia fault has a major earthquake every 525 years. The southern part, however, has one every 278 years. Therefore, the southern part of the Cascadia fault is overdue for a major earthquake because it has been 308 years since the last one.
According to Goldfinger, earthquakes occurring in this area "Don't often go past 300 years, so one is about due."
"I've heard that an earthquake is overdue," said Jeff Berwick, a freshman in biology. "It is supposed to happen any time now. It will definitely be interesting to see what happens when we do have one."
Quick Facts
OSU professor Chris Goldfinger and his team conducted research on the history of earthquakes by examining underwater geological deposits in the southersn Cascadia subduction zone and the northern San Andreas Fault.
- The last major earthquake in this region was 308 years ago
- The northern Cascadia subduction zone ruptures on average every 525 years
- The San Andreas Fault and Cascadia subduction zone have had earthquakes at the same geological time for the past 13 out of 15 quakes
- Research has revealed earthquake history for specific faults from as long as 10,000 years ago
See this previous 2001 article A Prelude to the Big Big One?
And big things are up again at Banda Aceh .. keep your eyes on Mount Merapi as well, as it appears to me that these are interlinked tec plates - if one tec plate moves, a corresponding one moves somewhere.
Last but not least, the current CANADIAN earthquake monitor picture - You can get this update information at http://earthquakescanada.nrcan.gc.ca/index_e.php.
The Big BoyZ and girlZ are accessing and analyzing this, why not you, too!
click within the boxes for regional information
