Tremor density by ETS

Plotted at the same scale are the last six northern Washington-southern Vancouver Island ETS events. These density plots are done by contouring the number of tremor locations at each grid point during the whole ETS. The blue arrows indicate the directions of propagation of the tremor over the whole ETS.
Note that for Fall 2012 it is only through Nov 4 and the ETS continues. Back to weekly tremor location comparisons.

WARNING: The density amplitude may be missleading because of double counting due to the same tremor location being reported by two different subnets.

-- Winter 2007 -- Jan 12 - Feb 2 (21 days) -- Spring 2008 -- Apr 30 - Jun 2 (34 days) -- Spring 2009 -- Apr 28 - Jun 3 (37 days)

-- Summer 2010 -- Aug 8 - Sep 8 (32days) -- Summer 2011 -- July 23 - Sep 4 (43 days) -- Fall 2012 -- July 30 - Oct 11 (42 days partial ETS)

-- Winter 2007 -- Jan 12 - Feb 2 (21 days)	-- Spring 2008 -- Apr 30 - Jun 2 (34 days)	-- Spring 2009 -- Apr 28 - Jun 3 (37 days)

-- Summer 2010 -- Aug 8 - Sep 8 (32days)	-- Summer 2011 -- July 23 - Sep 4 (43 days)	-- Fall 2012 -- July 30 - Oct 11 (42 days partial ETS)