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| Oso, WA landslide from JCW Seismograph (Jim Creek) of March 22nd. The middle energy signature is present in all graphs below for March 10, March 19-22 |
UW postdoctoral researcher
Kate Allstadt has a comprehensive post on
PNSN on
Seismic Signals generated by the Oso Landslide. Among the more interesting notes in her post is a
"sound recording" of the landslide at 160x speed. Local geologist Dan McShane has a number of excellent posts on the
geology of the region and the landslide itself. Chuck Forsberg of
Omen.com generously shipped me a dump of
VLF transmissions log from
Jim Creek Naval Station. The the
JCW seismographs compiled below show March 10th (date of 1.1 quake) and March 19 - 22. My guess is that the recurring 8 - 10 AM energy signature identified by
Kate Allstadt as a "cultural source" is probably some cycle of the nearby
250 KW VLF transmissions in
Jim Creek. Seismographs from
PNSN. Click to enlarge.
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From left to right: March 10, March 19 - 22. Note the two sharp disturbances early morning of March 21st; the day before the slide. Also note the persistent "cultural source" signature that shows up in each plot.
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Some notes on
VLF:
- VLF wavelengths are 10km to 100km long.
- Jim Creek Naval Radio Station is approximately 10km from the Oso, WA landslide.
- VLF wave generation requires large amounts of power for interesting reasons.
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