1. If we imagine for a moment that the signal found in the timeseries of YBHB is a real tectonic signal, then this diagram may be drawn comparing the onset time of a Slow Earthquake in Northern Cascadia in early We notice that not only does the signal at YBHB precede the Slow event in Northern Cascadia, but the event at NEWP and CORV occurs before this event as well. This possibility is a First- order scientific target for PBO/EarthScope

2. If we imagine for a moment that the signal found in the timeseries of YBHB is a real tectonic signal, then this diagram may be drawn comparing the onset time of a Slow Earthquake in Northern Cascadia in early We notice that not only does the signal at YBHB precede the Slow event in Northern Cascadia, but the event at NEWP and CORV occurs before this event as well. This possibility is a First- order scientific target for PBO/EarthScope

3. Vertical bars show known, GPS-detectable events
Blue means many stations or tremor, red likely but not robust
Nisqually event as a sanity check

4. If we imagine for a moment that the signal found in the timeseries of YBHB is a real tectonic signal, then this diagram may be drawn comparing the onset time of a Slow Earthquake in Northern Cascadia in early We notice that not only does the signal at YBHB precede the Slow event in Northern Cascadia, but the event at NEWP and CORV occurs before this event as well. This possibility is a First- order scientific target for PBO/EarthScope

5. ~Half of convergence is accommodated by large ETS events
Subtract from convergence rate of 34 mm/yr
This is the interseismic deformation field of the Pacific Northwest. The Juan de Fuca subducts beneath North America and drags the forearc NE. The interseismic signal diminishes get further away from the trench although it is still present beneath CWU, denoted by station LIND. Many other factors influence the interseismic deformation field of Cascadia: Basin and Range extension, northward impingement of the Sierra Nevada and oblique subduction are some of these mechanisms. Note the arrow directions. During the interseismic periods, elastic strain is built up in the forearc region.
~Half of convergence is accommodated by large ETS events
All imaged slip occurs below 25 km depth, above 40 km

6. But there’s more tremor outside the big events :
Aguiar et al., 2008
Smaller, sporadic tremor amounts to:
Aguiar: 20% of total tremor
Rogers/Kao: 30%, using ~10 yrs of data for Vancouver Island
Wech et al., 2008: 50% of total tremor
What is their moment release?

7. Aguiar et al., 2009 7

8. This is the interseismic deformation field of the Pacific Northwest
This is the interseismic deformation field of the Pacific Northwest. The Juan de Fuca subducts beneath North America and drags the forearc NE. The interseismic signal diminishes get further away from the trench although it is still present beneath CWU, denoted by station LIND. Many other factors influence the interseismic deformation field of Cascadia: Basin and Range extension, northward impingement of the Sierra Nevada and oblique subduction are some of these mechanisms. Note the arrow directions. During the interseismic periods, elastic strain is built up in the forearc region.

9. ETS-delineated coupling model:
GPS stations with ~10 years of measurements
Data from Leonard et al, 2004
ETS-delineated coupling model:
Replicates gross distribution of paleoseismic subsidence
This is the interseismic deformation field of the Pacific Northwest. The Juan de Fuca subducts beneath North America and drags the forearc NE. The interseismic signal diminishes get further away from the trench although it is still present beneath CWU, denoted by station LIND. Many other factors influence the interseismic deformation field of Cascadia: Basin and Range extension, northward impingement of the Sierra Nevada and oblique subduction are some of these mechanisms. Note the arrow directions. During the interseismic periods, elastic strain is built up in the forearc region.