Increasing public awareness that the Cascadia subduction zone in the Pacific Northwest is capable of great earthquakes (magnitude 9 and greater) motivates the Cascadia Initiative, an ambitious onshore/offshore seismic and geodetic experiment that takes advantage of an amphibious array to study questions ranging from megathrust earthquakes, to volcanic arc structure,...
We use regional broadband seismograms to obtain
seismic moment-tensor solutions of the two September 20, 1993,
Mw =6, Klamath Falls, Oregon earthquakes, their foreshock and
largest aftershocks (MD>3.5). Several sub-groups with internally
consistent solutions indicate activity on several fault segments
and faults. From the estimated moment-tensors and depths of the...
The Explorer region offshore western Canada is a tectonically complex area
surrounded by the Pacific, North America, and Juan de Fuca plates. Existing tectonic
models for the region differ fundamentally. Proposed plate configurations range from
multiple independent plate fragments to an Explorer plate now fused to North America
along the...
Here we use SKS shear wave splitting observations from ocean-bottom seismometer data to infer patterns of mantle deformation beneath the Juan de Fuca plate and its adjoining boundaries. Our results indicate that the asthenosphere beneath the Juan de Fuca plate responds largely to absolute plate motion with an anisotropic layer...
The Blanco Transform Fault Zone (BTFZ) forms the ~350 km long Pacific–Juan de
Fuca plate boundary between the Gorda and Juan de Fuca ridges. Nearby broadband seismic networks provide a unique framework for a detailed, long-term seismotectonic study of an entire oceanic transform fault (OTF) system. We use regional waveforms...
This paper presents the results from the Deflo-hydroacoustic experiment in the Southern Indian Ocean using three autonomous underwater hydrophones, complemented by two permanent hydroacoustic stations. The array monitored for 14 months, from November 2006 to December 2007, a 3000 x 3000 km wide area, encompassing large segments of the three...
Broadband body waves recorded at 15 digital seismic stations worldwide are used to study the rupture process of the May 23, 1989 Macquarie Ridge earthquake. The centroidal solution (strike 211°, dip 86°, rake 180°, and depth of 10 km below the seafloor) indicates shallow rupture with pure right-lateral strike-slip motion...
The way of slip transformation and strain partitioning at the eastern termination of the Kunlun
fault system remains unclear, and the question of whether this fault system is an important part for
lateral extrusion of Tibetan crust is debatable. The Tazang fault is regarded as the easternmost
continuation of the...
Maximum earthquake magnitude (m[subscript x]) is a critical parameter in seismic
hazard and risk analysis. However, some recent large earthquakes have shown that
most of the existing methods for estimating m[subscript x] are inadequate. Moreover, m[subscript x] itself is ill-defined because its meaning largely depends on the context, and it...
Teleseismic body waves from large earthquakes are used to study the downdip
geometry of continental normal faults in the Aegean. Waveform modeling technique together with rigorous statistical tests are applied to put firm bounds on the amount of downdip curvature of these faults and the role of coseismic slip on...