Geochemical monitoring of groundwater and soil gas emission pointed out precursor and/or coseismic anomalies of noble gases associated with earthquakes, but there was lack of plausible physico-chemical basis. A laboratory experiment of rock fracturing and noble gas emission was conducted, but there is no quantitative connection between the laboratory results and observation in field. We report ...

Recent observations have shown that shear waves trapped within lowvelocity fault zones may be the most sensitive measure of fault-zone structure (Li e t al. , 1994a, 1994b). Finite-difference simulations demonstrate the effects of several types of complexi ty on observations of fault-zone trapped waves. Overlying sediments with a thickness more than one or two fault-zone widths and fault-zone s...

Tem po ral b-value vari a tions have been com pletely ob tained for the seis mic fault ing pro cess of the 4 March 2008 Taoyuan earth quake (ML = 5.2), south ern Tai wan. In ad di tion to trig ger ing sev eral hun dred after shocks, the mainshock was pre ceded by two groups of foreshocks (64 events) that clus tered along the nar row ma jor fault zone. A high b-value of ~1.25, es ti mated from t...

We use SPOT image pairs to determine horizontal offsets associated with the Mw 7.9 November 2002 Denali earthquake in the vicinity of Slate Creek, AK. Field measurements and aerial photographs are used to further characterize the geometry of the surface rupture. Aerial photographs show that shear localization occurs where the rupture trace is linear, and distributed off-fault deformation is com...

We explore the issue of fault reactivation induced in enhanced geothermal systems by fluid injection. Specifically, we investigate the role of late stage activation by thermal drawdown. A Thermal-Hydrological-Mechanical simulator incorporating a ubiquitous joint constitutive model is used to systematically simulate the seismic slip of an embedded critically stressed strike-slip fault. We examin...

[1] Hydraulic diffusivity controls fluid pressure and hence affects effective normal stress during rupture. Models suggest a particularly spectacular example of fluid pressurization during the Mw = 7.6 1999 Chichi earthquake when pressurization may have reduced highfrequency shaking in the regions of large slip if the fault was sufficiently sealed. We investigate in situ hydraulic diffusivity w...

[1] Several lines of evidence, including remote triggering of earthquakes and modulation of seismic tremor by Earth tides, suggest that faults weakenwhen subject to shaking and dynamic stresses associatedwith the passage of seismic waves. However, the origin of such dynamic weakening is poorly understood. Here we explore the role of acoustic resonance for dynamic fault weakening using laborator...

Precise factors controlling the coevolution of deformation and topography in tectonically active landscapes remain poorly understood due to complex feedbacks between numerous possible variables. Here we examine the links between fault kinematics, emergent topography, and environmental factors on a global data set of active fault-driven mountain ranges (n = 41). Using simple regressions between ...

Two tectonic scenarios have been proposed for genesis and emplacement of the Oman ophiolite. One suggests that the ophiolite was generated at a spreading center, the other suggests generation within an intraoceanic arc. An integrated thermal and kinematic model of the temperature, stress, rock type, and displacement fields during early stages of the emplacement ofthe Oman ophiolite was develope...