Recent modeling studies have explored whether earthquakes begin with a large aseismic nucleation process or initiate dynamically from the rapid growth of a smaller instability in a “cascade-up” process. To explore such a case in the laboratory, we study the initiation of dynamic rupture (stick slip) of a smooth saw-cut fault in a 76mm diameter cylindrical granite laboratory sample at 40–120MPa ...

a r t i c l e i n f o Recent high-resolution GPS and seismological data reveal that tectonic faults exhibit complex, multi-mode slip behavior including earthquakes, creep events, slow and silent earthquakes, low-frequency events and earthquake afterslip. The physical processes responsible for this range of behavior and the mechanisms that dictate fault slip rate or rupture propagation velocity ...

The Pasadena earthquake (ML ~4.9) occurred on 3 December 1988, at a depth of 16 km. The hypocenters of the earthquake and its aftershocks define a eastnortheast striking, steeply northwest-dipping surface that projects up to the active surficial trace of the Raymond fault. One of the nodal planes of the focal mechanism of the earthquake parallels the Raymond fault with left-lateral strikeslip m...

Technical Abstract We determined orientations of principal stresses around the San Andreas Fault (SAF) system in the greater San Francisco Bay Area and regions further north along the strike-slip plate boundary. Stress orientations, as well as a ratio between stress magnitudes, were determined by inversions of approximately 6000 earthquake fault plane solutions, divided into ~100 groups based o...

Abundant geological, seismological and experimental evidence of the heterogeneous structure of natural faults motivates the theoretical and computational study of the mechanical behavior of heterogeneous frictional interfaces. Fault zones are composed of a mixture of materials with contrasting strength, which may affect the spatial variability of seismic coupling, the location of high-frequency...

Fault creep, depending on its rate and spatial extent, is thought to reduce earthquake hazard by releasing tectonic strain aseismically. We use Bayesian inversion and a newly expanded GPS data set to infer the deep slip rates below assigned locking depths on the San Andreas, Maacama, and Bartlett Springs Faults of Northern California and, for the latter two, the spatially variable interseismic ...

The 11 March 2011 Mw9.0 Tohoku-Oki earthquake was recorded by an exceptionally large amount of diverse data offering a unique opportunity to investigate the details of this major megathrust rupture. Many studies have taken advantage of the very dense Japanese onland strong motion, broadband, and continuous GPS networks in this sense. But resolution tests and the variability in the proposed solu...

The spatial and temporal distribution of fault slip is a critical parameter in earthquake source models. Previous geomorphic and geologic studies of channel offset along the Carrizo section of the south central San Andreas Fault assumed that channels form more frequently than earthquakes occur and suggested that repeated large-slip earthquakes similar to the 1857 Fort Tejon earthquake illustrat...

The 2011 Tohoku earthquake (Mw 9.0) produced a very large slip on the shallow part of a megathrust fault that resulted in destructive tsunamis. Although multiple causes of such large slip at shallow depths are to be expected, the frictional property of sediments around the fault, particularly at coseismic slip velocities, may significantly contribute to large slip along such faults. We have thu...

The formation of fault damage due to slip under high normal stresses can rarely be monitored under in situ conditions. To advance our understanding of microfracture processes, we investigated stick-slip events on Westerly granite samples containing the following: (1) a planar saw cut fault and (2) a fault developed from a fresh fracture surface. We examined temporal changes of seismic moment te...