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Hurricane Julliete causes increase in seismic 'noise'

The Anza group at the University of California San Diego operates a broadband seismograph network consisting of 13 (+ 2) three component broadband seismograph stations centered near Anza Californa.

On Friday, September 28th, 2001 we noticed that on a long time scale, the noise levels at our seismic stations were extremely high.

Here is a plot showing the vertical component of all of the Anza stations. The plot immediately below shows 3 days of data with the oldest data at the left hand side of the figure. Click the image for an enlarged view.

This next figure (from the National Weather Service/National Hurricane Center) shows the wind strengths along the hurricane track. Note that as the hurricane approaches Southern California the microseism noise increases. Click the image for an enlarged view.

To view the latest tracking data from the National Weather Service, visit the National Hurricane Center.

Finally, here is a plot that shows seven days of data. You see the initial data shows a baseline signal (through julian day 2001269). The microseisms increase as the storm approaches and/or strengthens (2001269-2001272). As the storm weakens the microseism die out and we return to the normal background signal (2001273). Click the image for an enlarged view.

Dr. Vera Schulte-Pelkum has researched other microseism events at Anza. We hope to continue this work in the upcoming weeks using the data collected from this event. Please see a summary of her work on microseismis that was used in a recent proposal for funding for the ANZA network.

Learn more about the Anza group (including who works here, other networks, nuclear tests in China/India/Pakistan).
Learn more about the ANZA network (includes more station information, research, etc).

URL: http://eqinfo.ucsd.edu/special_events/2002/151/a/index.html