Blanco Fracture Zone
The Blanco Fracture Zone or Blanco Fault Zone (BFZ) is a transform fault zone running northeast off the coast of Oregon in the Pacific Northwest of the United States which runs between the Gorda Ridge to the south and the Juan de Fuca Ridge to the north. The principal feature of the Blanco zone is the Blanco Ridge, a right lateral-moving fault which also incorporates some compression, thus accounting for the uplift expressed in the ridge. The ridge is not an oceanic spreading center, despite its name, whereas the Juan de Fuca and Gorda Ridges to which it is connected are. Similarly confusing, the portion of the Blanco Fracture Zone which lies east of the rift zone spreading center is not technically a true fracture zone, but a transform fault zone.
In March and April 2008, a series or swarm of moderate earthquakes occurred both near and within the Blanco zone. The swarm began on March 30 when over 600 measurable tremors began occurring north of the zone within the Juan de Fuca Plate. On April 22, activity moved to the Blanco fault zone itself, near its junction with the Gorda Ridge.
- Dziak, R. P.; Fox, C. G.; Embley, R. W.; Nabelek, J. L.; Braunmiller, J.; Koski, R. A. (2000). "Recent tectonics of the Blanco Ridge, eastern blanco transform fault zone". Marine Geophysical Researches. Springer Science+Business Media. 21 (5): 423–450.
- "2008 Oregon Offshore Earthquakes". NOAA. Retrieved 2008-08-27.
- USGS - Offshore Oregon Sequence
- Oregon State University - Earthquake Swarm
- Cascadia tectonic history