Spring Break
Researchers size up seismic activity
Earthquake activity in Maupin, ORe. has OSU scientists looking for cause
Rebecca Johnson
Issue date: 1/14/09 Section: News
The small town of Maupin, located in Eastern Oregon, has been experiencing a large number of earthquakes over the past two years, and OSU researchers are trying to figure out why.
There have been around 350 earthquakes since December 2006. While most of them go unnoticed except by the seismometers, around 15 have reached a magnitude strong enough to be felt by the surrounding community, according to Jochen Braunmiller, research assistant for the OSU College of Oceanic and Atmospheric Sciences (COAS).
Braunmiller explained that there have been several questions that have arisen while researching these earthquakes.
One is that these swarms do not follow the mainshock/aftershock sequence of most earthquakes. In many cases, there will be a large earthquake (the mainshock) followed by numerous smaller earthquakes that decrease over time, also known as the aftershocks.
In Maupin, there was no large earthquake, only numerous small ones that have not stopped, the last of which occurred Dec. 27 of last year.
The fact that the activity has been going on for two years is also unusual because with many swarms, the tremors will begin to taper off as stress is released from the fault.
These swarms have also been occurring in other parts of the nation. The United States Geological Survey reported several hundred small earthquakes at Yellowstone National Park at the end of December 2008. While swarms are not uncommon for Yellowstone, the activity was much higher than the area is used to seeing.
The occurrence in Yellowstone also raises another question: the depth at which the Maupin earthquakes are occurring. In Yellowstone, the small quakes are fairly shallow, originating only three miles below the surface. In Maupin, the earthquakes are occurring at a depth of around 10 miles.
This depth causes a problem for one of the theories regarding the activity's causes. Braunmiller explained that there have been some fluid pressure changes locally along the fault. The presence of water in a fault can make it easier for plates to break away and start sliding.
There have been around 350 earthquakes since December 2006. While most of them go unnoticed except by the seismometers, around 15 have reached a magnitude strong enough to be felt by the surrounding community, according to Jochen Braunmiller, research assistant for the OSU College of Oceanic and Atmospheric Sciences (COAS).
Braunmiller explained that there have been several questions that have arisen while researching these earthquakes.
One is that these swarms do not follow the mainshock/aftershock sequence of most earthquakes. In many cases, there will be a large earthquake (the mainshock) followed by numerous smaller earthquakes that decrease over time, also known as the aftershocks.
In Maupin, there was no large earthquake, only numerous small ones that have not stopped, the last of which occurred Dec. 27 of last year.
The fact that the activity has been going on for two years is also unusual because with many swarms, the tremors will begin to taper off as stress is released from the fault.
These swarms have also been occurring in other parts of the nation. The United States Geological Survey reported several hundred small earthquakes at Yellowstone National Park at the end of December 2008. While swarms are not uncommon for Yellowstone, the activity was much higher than the area is used to seeing.
The occurrence in Yellowstone also raises another question: the depth at which the Maupin earthquakes are occurring. In Yellowstone, the small quakes are fairly shallow, originating only three miles below the surface. In Maupin, the earthquakes are occurring at a depth of around 10 miles.
This depth causes a problem for one of the theories regarding the activity's causes. Braunmiller explained that there have been some fluid pressure changes locally along the fault. The presence of water in a fault can make it easier for plates to break away and start sliding.
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