TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 57 (No. 4), p. 369, 2005


Geodetic and seismic signatures of episodic tremor and slip in the northern

Cascadia subduction zone

H. Dragert, K. Wang, and G. Rogers

Earth Planets Space, Vol. 56, pp. 1143-1150, 2004

The caption for Fig. 7 on p. 1148 should read as follows:

Conceptual model for plate motions and stress accumulation across the CSZ interface. The permanent relative displacements and changes in shear stress across the interface are sketched as functions of time in each zone. The transition of the displacement/stress behaviour from that in the locked zone to that in the ETS zone is not well defined but may provide a new basis for defining the "transition zone". Stars represent sources of tremors that accompany slip events.

The caption for Fig. 8 on p. 1148 should read as follows:

Distribution of slip deficit at CSZ interface across the northern Cascadia margin. Slip-deficit rates needed for back-slip modeling of the interseismic and inter-slip surface velocities are shown schematically and are not quantitative. The nominal locked or "brittle" zone extends from (near) surface downdip to the T1 isotherm (depth ~15 km), and is subject to full plate-rate slip deficit. The linear transition zone used by Flueck et al. (1997) extends from the T1 to T2 isotherm (depth ~25 km). It was previously assumed that free slip occurred downdip from T2. Wang et al. (2003) proposed an "effective" transition zone extending from the T1 to T3 isotherm (depth ~45 km) whose temporal average slip-deficit is given by an exponential decay from full to zero (orange curve). This revision was required to account for the higher long-term deformation rates observed at inner margin GPS sites. The red line shows the down-dip slip deficit required during the 14.5 mo period between occurrences of slip to account for the augmented strain accumulations which are released at the time of slow earthquakes.

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