Reflection signature of seismic and aseismic slip on the northern Cascadia subduction interface

  title={Reflection signature of seismic and aseismic slip on the northern Cascadia subduction interface},
  author={Mladen R. Nedimovi{\'c} and Roy D. Hyndman and Kumar Ramachandran and George D. Spence},
At the northern Cascadia margin, the Juan de Fuca plate is underthrusting North America at about 45 mm yr-1 (ref. 1), resulting in the potential for destructive great earthquakes. The downdip extent of coupling between the two plates is difficult to determine because the most recent such earthquake (thought to have been in 1700) occurred before instrumental recording. Thermal and deformation studies indicate that, off southern Vancouver Island, the interplate interface is presently fully locked… 
A wide depth distribution of seismic tremors along the northern Cascadia margin
The observed depth range implies that tremors could be associated with the variation of stress field induced by a transient slip along the deeper portion of the Cascadia interface or, alternatively, that episodic slip is more diffuse than originally suggested.
Seismic reflection imaging of two megathrust shear zones in the northern Cascadia subduction zone
Deep seismic reflection data from the northern Cascadia subduction zone are presented that show that the inter-plate boundary is up to 16 km thick and comprises two megathrust shear zones that bound a >5km-thick, ∼110-km-wide region of imbricated crustal rocks.
Geodetic and seismic signatures of episodic tremor and slip in the northern Cascadia subduction zone
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
Local thickening of the Cascadia forearc crust and the origin of seismic reflectors in the uppermost mantle
Seismic reflection profiles from three different surveys of the Cascadia forearc are interpreted using P wave velocities and relocated hypocentres, which were both derived from the first arrival
Relationship between the Cascadia fore‐arc mantle wedge, nonvolcanic tremor, and the downdip limit of seismogenic rupture
Great earthquakes anticipated on the Cascadia subduction fault can potentially rupture beyond the geodetically and thermally inferred locked zone to the depths of episodic tremor and slip (ETS) or to
Probable low-angle thrust earthquakes on the Juan de Fuca- North America plate boundary
In 2004, two clusters of earthquakes occurred in the central part of the Cascadia forearc, which displays several characteristics indicative of along-strike and downdip variations in plate coupling.
Downdip landward limit of Cascadia great earthquake rupture
[1] This paper examines the constraints to the downdip landward limit of rupture for the Cascadia great earthquakes off western North America. This limit is a primary control for ground motion hazard
Cascadia low frequency earthquakes at the base of an overpressured subduction shear zone
The authors show that slow slip earthquakes at the Cascadia subduction zone occur immediately below a 6-10 km-thick shear zone, in which slab-derived fluids are likely trapped at near-lithostatic pore pressures.
SAHKE seismic‐scatter imaging of subduction beneath Wellington, North Island, New Zealand
Scattering reflectivity analysis of onshore seismic data (Seismic Array HiKurangi Experiment) images slab geometry and crustal structure at a geodetically locked subduction boundary. A broad seismic
Correlation of porosity variations and rheological transitions on the southern Cascadia megathrust
The unknown onshore extent of megathrust earthquake rupture in the Cascadia subduction zone represents a key uncertainty in earthquake hazard for the Pacific Northwest that is governed by the


Seismic reflection constraints on imbrication and underplating of the northern Cascadia convergent margin
An interpretation of the deep structure of the continental shelf offshore southern Vancouver Island, subject to constraints from other geophysical data, is derived by combining seismic reflection
The rupture zone of Cascadia great earthquakes from current deformation and the thermal regime
An important but poorly -known part of the earthquake hazard at near-coastal cities of western North America from southern British Columbia to northern California is from great thrust earthquakes on
The northern Cascadia subduction zone at Vancouver Island: seismic structure and tectonic history
The structure and Tertiary tectonic history of the northern Cascadia subduction zone have been delineated by a series of new multichannel seismic lines acquired across the continental shelf to the
A Silent Slip Event on the Deeper Cascadia Subduction Interface
Continuous Global Positioning System sites in southwestern British Columbia, Canada, and northwestern Washington state, USA, have been moving landward as a result of the locked state of the Cascadia
Crustal structure beneath the Strait of Juan de Fuca and southern Vancouver Island from seismic and gravity analyses
[1] Wide-angle and vertical incidence seismic data from Seismic Hazards Investigations in Puget Sound (SHIPS), gravity modeling, and seismicity are used to derive two-dimensional crustal models
Shear wave constraints on a deep crustal reflective zone beneath Vancouver Island
Analysis of teleseismic receiver functions recorded in the northern Cascadia subduction zone show that large P-to-S converted phases are generated at the boundaries of a dipping layer of deep crustal
▪ Abstract We present preliminary evidence for a ∼10,000-year earthquake record from two major fault systems based on sediment cores collected along the continental margins of western North America.
Seismic evidence for widespread serpentinized forearc upper mantle along the Cascadia margin
Petrologic models suggest that dehydration and metamorphism of subducting slabs release water that serpentinizes the overlying forearc mantle. To test these models, we use the results of
Deep, high-amplitude reflections from a major shear zone above the subducting Juan de Fuca plate
Seismic reflection data show that a regionally extensive band of landward-dipping reflections exists above the subducting Juan de Fuca plate at the western Canadian continental margin. The
An inverted continental Moho and serpentinization of the forearc mantle
Very low shear-wave velocities are found in the cold forearc mantle indicated by the exceptional occurrence of an ‘inverted’ continental Moho, which reverts to normal polarity seaward of the Cascade arc, providing compelling evidence for a highly hydrated and serpentinized forearc region, consistent with thermal and petrological models of the Forearc mantle wedge.