Open Access

Geodetic and seismic signatures of episodic tremor and slip in the northern Cascadia subduction zone

Earth, Planets and Space201456:BF03353333

Received: 2 June 2004

Accepted: 24 December 2004

Published: 26 June 2014

The Erratum to this article has been published in Earth, Planets and Space 2014 57:BF03352578


Slip events with an average duration of about 10 days and effective total slip displacements of severalc entimetres have been detected on the deeper (25 to 45 km) part of the northern Cascadia subduction zone interface by observing transient surface deformation on a network of continuously recording Global Positioning System (GPS) sites. The slip events occur down-dip from the currently locked, seismogenic portion of the subduction zone, and, for the geographic region around Victoria, British Columbia, repeat at 13 to 16 month intervals. These episodes of slip are accompanied by distinct, low-frequency tremors, similar to those reported in the forearc region of southern Japan. Although the processes which generate this phenomenon of episodic tremor and slip (ETS) are not well understood, it is possible that the ETS zone may constrain the landward extent of megathrust rupture, and conceivable that an ETS event could precede the next great thrust earthquake.

Key words

Crustal deformation GPS slow earthquakes non-volcanic tremors Cascadia margin