Second Magnitude 4.5 Earthquake Near Yorba Linda- August 8, 2012

The Quake

This morning at 9:33am, a Magnitude 4.5 earthquake struck near Yorba Linda, California. It caused moderate shaking throughout the area surrounding the epicenter and caused Mild to Weak Shaking throughout the Greater Los Angeles Area. The earthquake is most likely an aftershock to the earthquake last night. Unlike the earthquake last night, it was shallower, at a depth of only 5 miles, causing it to have slightly stronger shaking than the main shock.

Reflecting off of the Quake

Update 11/10/12: Doug Given, one of the leaders of the Shakealert program stated that during the two earthquakes Caltech received 9 seconds of warning on the first quake and 4 seconds on the second quake.

If this earthquake had been larger, and an earthquake early warning system had been in place, a short warning could have been given to the Los Angeles Area. However there would have been a blind zone where no warning could be given.

The Chino Hills Earthquake of 2008 occurred in a similar location, and had there been a functioning system at the time, and had the earthquake been larger, a warning could have been given. Please Note that the warning would have been shorter than shown because would take at least 5 seconds after detection to process the earthquake before sending out a warning.

The video of the ShakeAlert System was created by the US Geological Survey, Caltech, UC Berkley, and the other organizations creating the system.

The amount of warning time given depends on your distance from the epicenter. The farther you are from the epicenter, the more warning you would receive. The problem is, that the farther you are from the epicenter, the shaking is usually weaker (unless an earthquake occurs along an entire fault).

The amount of warning that could be given for a large earthquake on the southern San Andreas Fault is shown at the right. Almost an entire minute of warning could be given to the Los Angeles Area.

Although an earthquake early warning system could help save lives during an earthquake, there is little funding for the system, and very few people have even heard of them.

Please see my older post on earthquake early warnings from July 2012

For more information visit:
http://www.eew.caltech.edu/