New data are presented that provide evidence for the onset of extensional deformation in the Northwestern Basin and Range within 1 million years after the eruption of the Steens Basalt at 16.5 Ma. New geologic mapping (1:24,000), stratigraphic sections, and ⁴⁰Ar/³⁹Ar dating of the Crane Basin rocks provide a control...
The two largest earthquakes ever recorded, the 1964 M[subscript w] 9.2 Alaskan and 1960 M[subscript w] 9.5 Chilean, occurred on seismogenic plate interfaces at subduction zones. It has been theorized that the catastrophic failure of a locked zone along the contact between the downgoing slab and the upper plate causes...
A large, damaging earthquake in 1944 on a blind thrust fault caused 60 cm of surface rupture on the subsidiary La Laja fault and additional unmeasured growth of an associated backlimb fold. Both the fold and fault are components of the La Laja Fault System (LLFS) located 25 km northeast...
Passive hydrophone technologies and a variety of acoustic methods are applied in
the deep-ocean and shallow water coastal environments of the northeast Pacific. A
catalog derived from U.S. Navy regional hydrophone array recordings of acoustic T- phases from seafloor earthquakes is examined, describing space/time patterns through
empirical orthogonal function analysis...
The Mount Polley copper-gold deposit is one of a series of porphyry copper deposits that occur in a belt of accreted Mesozoic age island arc terranes in the Canadian Cordillera. The deposit comprises three breccia-hosted Cu-Au ore zones that are associated with a series of monzodiorite to monzonite intrusions emplaced...
Oblique subduction of the Juan de Fuca plate beneath the North American plate characterizes the tectonic setting of the Pacific Northwest. North American plate deformation at the latitude of central Oregon consists of the clockwise-rotation of the Siletzia block in the forearc and the extensional Basin and Range province in...
The details of the 1700 Cascadia Subdction Zone earthquake and tsunami can be better constrained using data from tsunami sand sheets, provided knowledge of the waveform, estuary geometry and bed roughness controls on the deposition pattern of the sand sheet. In this study, we use the hydrodynamic and sediment transport...
Despite more than two centuries of exploration, including more than six million deep wellbores with depths exceeding 40,000 feet in some parts of the world, our ability to constrain subsurface processes and properties remains limited. Characteristics of the subsurface vary and can be analyzed on a variety of spatial scales....
Numerous investigations demonstrate that mantle convective processes such as upwelling affect the surface topography of the overriding plate. The surface expression of mantle flow has been coined ‘transient topography’. Transient topography in the North American plate is thought to result from a mantle thermal anomaly beneath the Yellowstone volcanic center,...
Three key tectonic domains of western North America, the Walker Lane Fault Zone (WLFZ), northwestern Basin and Range (NWBR), and Cascade arc, intersect in south-central Oregon. Bounded by Cascade arc volcanoes in the west, the Klamath Graben is traditionally regarded as the western-most extent of the Basin and Range extensional...