Big Skidder experiment: tracking non-volcanic tremor through beamforming
|
The experiment:
We installed an 84-element vertical-channel small-aperture dense seismic array, and recorded the May
2008 ETS event, and a tremor episode two months earlier. Applying a beamforming technique, we are able
to detect up to 4 times more duration of non-volcnic tremor activity than the detection using a conventional envelope
cross-correlation method. The map below shows location and station geometry of the Big Skidder array.
|
|
Beamforming:
The movie below tracks time evolution of tremor beams at 3-8 Hz, 5 minutes time window with 2.5 minutes overlap, 10th
May, 2008. Left panel shows beams with variable amplitude scale, while right panel has
a fixed amplitude scale (log10), and illustrates the temporal variation in relative
tremor amplitude. Green star shows tremor location using an envelope cross-correlation method.
Click on the link below to view and/or download the full size movie.
|
|
Restless tremor:
The movie below shows how tremor migrate on 7th May, 2008, a day of strong tremor action
during 2008 ETS event. If you look closely, you may find some short-term tremor migration events. For tremor
source location, we use the slowness from beam, and raytrace it to the subduction interface (contour
lines). Square box represent the location of the Big Skidder array.
Click on the link below to view and/or download the full size movie.
|
|
|
|
|
|
Last updated by Abhijit Ghosh on May 12th, 2009
|
