[SIO GP Seminars] Friday Seminar at NEW TIME - 3:15 Elizabeth Cochran

[Leah Ziegler]

Join us this Friday for this week's Geophysics Seminar.  Please note 
the small CHANGE IN MEETING TIME from 3 to 3:15.  See below for more 
info on this week's seminar.


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Friday, October 6, 3:15 PM
   (refreshments served at 3:00 PM)
   Munk Conference Room
    
Elizabeth Cochran

   "Infrasound events detected with the Southern California Seismic 
Network"
   
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ABSTRACT
We examine continuous data from the Southern California Seismic Network 
from 2003 and identify infrasound acoustic waves from 76 previously 
undetected events. Using waveform cross-correlation of the signal 
envelope functions, we determine their relative arrival times and 
estimate source locations. The waves travel at acoustic speeds of ~320 
m/s and are observed in seismic records up to 450 km from their 
probable source locations off the west coast of southern California. 
The dominant daylight occurrence of the events points to a man-made 
source related to military activity. The events are mostly recorded in 
the winter and spring when atmospheric conditions trap acoustic energy 
near the Earth's surface and favor propagation to the west. These 
results suggest that data from regional and global seismic networks can 
supplement observations from infrasound arrays for Comprehensive Test 
Ban Treaty monitoring and geophysical applications such as volcano 
monitoring, bolide detection, atmospheric acoustic sources and 
tomography.
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