Kinematic data from two segments of the Coast Range fault are used to test the hypothesis that the Franciscan subduction complex was exhumed by extensional faulting. The data reveal a consistent geometry for the principal directions of brittle strain. The maximum extension direction has an east-west orientation and lies subperpendicular to the present attitude of the Coast Range fault, which di...

Although there is enough knowledge indicating on the influence of frequency content of input motion on the deformation demand of structures, state-of-the-practice seismic studies use the intensity measures such as peak ground acceleration (PGA) which are not frequency dependent. The ratio of strong ground motions can be used in seismic hazard studies as the representative of frequency content o...

Tests of two fault boundary conditions show that each converges with second order accuracy as the finite-difference grid is refined. The first method uses split nodes so that there are disjoint grids that interact via surface traction. The 3D version described here is a generalization of a method I have used extensively in 2D; it is as accurate as the 2D version. The second method represents fa...

Conflicting views of circum-Pacific tectonics have focused on the PhilippinesTaiwan region, where there has been neither convincing documentation nor general agreement on the importance of transcurrent (strike-slip) faulting or the possible sense of regional horizontal displacement. Structural and physiographic features of the 1200-km-long Philippine fault zone are fully as spectacular as those...

This paper reviews rock friction and the frictional properties of earthquake faults. The basis for rateand state-dependent friction laws is reviewed. The friction state variable is discussed, including its interpretation as a measure of average asperity contact time and porosity within granular fault gouge. Data are summarized showing that friction evolves even during truly stationary contact, ...

We have synthesized the characteristics of the seismogenic zone in the east Los Angeles basin by analyzing earthquake data recorded during the past 30 years (1981–2010). The seismicity is distributed along the Whittier fault, with the majority of earthquakes located adjacent to the south side, in the depth range from 0 to 9 km, with b value of 1:1 0:05 and mostly normal and strike-slip faulting...

Dike emplacement in volcanic rift zones is often associated with the injection of “bladelike” dikes, which propagate long distances parallel to the rift, but frequently remain trapped at depth and erupt only near the tip of the dike. Over geologic time, this style of dike injection implies that a greater percentage of extension is accommodated by magma accretion at depth than near the surface. ...

The authors are one of five teams developing empirical ground motion (attenuation) relations for active shallow crustal regions as part of the PEER Next Generation Attenuation (NGA) Project. Each Developer Team was provided with a common database of worldwide strong-motion recordings and supporting metadata, but was given the freedom to use separate data selection criteria, parameters, function...

We present a new, high spatial resolution image of stress orientation in southern California based on the inversion of earthquake focal mechanisms. We use this image to study the mechanics of faulting in the plate boundary region. The stress field contains significant spatial heterogeneity, which in some cases appears to be a result of the complexity of faulting and in other cases appears to be...