Friday, March 28, 2014

Oso Landslide Part I: Data from Oso and Jim Creek Naval Station

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 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.
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. 

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.
March 19 - 23. VLF signals from Jim Creek Naval Radio Station  . Data provided courtesy of  Chuck Forsberg of

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