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J.D. Byerlee

Publications and source records attributed to J.D. Byerlee.

At least 37 records · Page 2Linked to original sources
USGS1992

An earthquake mechanism based on rapid sealing of faults

Recent seismological, heat flow and stress measurements in active fault zones such as the San Andreas have led to the suggestion 1,2 that such zones can be relatively weak. One explanation for this may be the presence of overpressured fluids along the fault 3–5 , which would reduce the shear stress required for sliding by partially 'floating' the rock. Although several mechanisms have been proposed for overpressurizing fault fluids 3,4,6,7 , we recall that 'pressure seals' are known to form in both sedimentary 8 and igneous 9 rocks by the redistribution of materials in solution; the formation of such a seal along the boundaries of a fault will prevent the communication of fluids between the porous, deforming fault zone and the surrounding country rock. Compaction of fault gouge, under hydrostatic loading and/or during shear, elevates pore pressure in the sealed fault and allows sliding at low shear stress. We report the results of laboratory sliding experiments on granite, which demonstrate that the sliding resistance of faults can be significantly decreased by sealing and compaction. The weakening that results from shear-induced compaction can be rapid, and may provide an instability mechanism for earthquakes.

Nature↗
USGS1991

Quasi-static fault growth and shear fracture energy in granite

The failure process in a brittle granite sample can be stabilized by controlling axial stress to maintain a constant rate of acoustic emission. As a result, the post-failure stress curve can be followed quasistatically, extending to hours the fault growth process which normally would occur violently in a fraction of a second. Using a procedure originally developed to locate earthquakes, acoustic emission arrival-time data are inverted to obtain three-dimensional locations of microseisms. These locations provide a detailed view of fracture nucleation and growth.

Nature↗
USGS1991

Comparative geometry of the San Andreas Fault, California, and laboratory fault zones

Textural examination of fault gouge deformed in triaxial friction experiments has revealed differences in the orientations of secondary shear sets between the stably sliding and stick-slip samples. In order to determine whether such differences can be identified in natural faults, maps of recently active breaks along the San Andreas fault from Point Arena to Cajon Pass, California, were examined to compare the types and orientations of secondary structures mapped in the creeping and locked sections. The fault zone was divided into 52 geometrically defined segments of uniform strike, which were then grouped into 7 sections: 4 straight and 2 curved sections, and Cholame Valley. One of the straight sections is the creeping section between San Juan Bautista and Cholame in central California; the rest of the sections are locked. Many of the gross geometric characteristics of the individual segments, such as length, width, and stepover size, reflect their position in either a straight or a curved section. In contrast, with respect to the orientations of the recent breaks within the segments, the single creeping section differs from all of the locked sections, both straight and curved, as follows: (1) the traces of recent breaks with a more west-ward orientation than the local strike of the fault zone (P traces) dominate over those with a more northward orientation (R traces) in the creeping section, whereas the opposite relationship holds in the locked sections, and (2) the more northward-oriented (R) traces make larger angles to the local strike of the fault zone in the locked sections than in the creeping section. The latter result is consistent with the orientations of R shears in our various laboratory samples. The former result was unexpected, because of the predominance of R shears in most laboratory samples, but a small number of samples are analogous to the creeping section in terms of their P-shear abundances, R-shear orientations, and sliding behavior. The causes of these distinguishing characteristics are not yet understood.

California↗
USGS1991

A note on the frictional strength of laumontite from Cajon Pass, California

Laumontite mineralization is pervasive in joints and shear zones encountered in the Cajon Pass drillhole in southern California. In order to determine whether a gouge composed of this hydrated mineral affects shear strength in a manner similar to low-strength, clay-rich fault gouges, frictional sliding experiments were performed under dry, saturated and high pore pressure conditions at effective pressures up to 450 MPa. Coefficients of friction ranged between 0.66 and 0.84, consistent with most crustal rocks and well above the values typical of clay-rich San Andreas fault gouges. Saturation state had no effect on strength or sliding stability. These results suggest that the presence of laumontite in shear zones at Cajon Pass will not affect the shear strength of the rock in a way that can account for the inferred low ambient shear stresses. -Authors

Geophysical Research Letters↗
USGS1990

Textural development of clayey and quartzofeldspathic fault gouges relative to their sliding behavior

Many of the secondary fault structures developed during triaxial friction experiments have been generally correlated with the structures of natural fault zones. Therefore, any physical differences that can be found between laboratory samples that slide stably and those that show stick-slip motion may help to identify the cause of earthquakes. We have examined petrographically the run products of many triaxial friction experiments using clayey and quartzofeldspathic gouges, which comprise the principal types of natural fault gouge material. The examined samples were tested under a wide range of temperature, confining and fluid pressure, and velocity conditions. The clayey and quartzofeldspathic gouges show some textural differences, owing to their different mineral contents and grain sizes and shapes. In the clayey gouges, for example, a clay mineral fabric and kink band sets are commonly developed, whereas in the quartzofeldspathic gouges fracturing and crushing of the predominately quartz and feldspar grains are important processes. For both types of gouge, however, and whatever the pressure-temperature-velocity conditions of the experiments, the transition from stable sliding to stick-slip motion is correlated with: (i) a change from pervasive deformation of the gouge layer to localized slip in subsidiary shears; and (ii) an increase in the angle betweem the shears that crosscut the gouge layer (Riedel shears) and ones that form along the gouge-rock cylinder boundaries (boundary shears). This suggests that the localization of shear within a fault zone combined with relatively high Riedel-shear angles are somehow connected with earthquakes. Secondary fracture sets similar to Riedel shears have been identified at various scales in major strike-slip faults such as the San Andreas of the western United States (Wallace, 1973) and the Luhuo and Fuyun earthquake faults of China (Deng and Zhang, 1984; Deng et al. , 1986). The San Andreas also contains locked and creeping sections that correspond to the stick-slip and stably sliding experimental samples, respectively. We plan to study the physical structure of the San Andreas fault, to see if the experimentally observed differences related to sliding behavior can also be distinguished in the field.

Physics and Chemistry of the Earth↗
USGS1989

Sliding behavior and deformation textures of heated illite gouge

The run products of a series of triaxial friction experiments on an illite-rich gouge have been examined petrographically to study the relationship between textural development and sliding mode. The samples show a complete range of textures, from ones in which the entire gouge layer is deformed to ones in which the deformation is concentrated along narrow subsidiary shears and the rest of the gouge layer is massive. The samples with a pervasively developed deformation fabric slide stably, whereas the samples containing shear bands show stick-slip motion if the intersection angles between boundary-parallel and cross-cutting (Riedel) shears are also relatively high. These textural differences suggest that localization of shear combined with higher-angle Riedel shears are somehow involved in stick-slip motion. The orientation of Riedel-type shears in natural fault zones may also have potential as a paleoseismological tool.

Journal of Structural Geology↗
USGS1989

Experimental studies of compaction and dilatancy during frictional sliding on faults containing gouge

Transient strength changes are observed in fault gouge materials when the velocity of shearing is varied. A transient stress peak is produced when the strain rate in the gouge is suddenly increased, whereas a transient stress drop results from a sudden change to a slower strain rate. We have studied the mechanism responsible for these observations by performing frictional sliding experiments on sawcut granite samples filled with a layer of several different fault gouge types. Changes in pore volume and strength were monitored as the sliding velocity alternated between fast and slow rates. Pore volume increased at the faster strain rate, indicating a dilation of the gouge layer, whereas volume decreased at the slower rate indicating compaction. These results verify that gouge dilation is a function of strain rate. Pore volume changed until an equilibrium void ratio of the granular material was reached for a particular rate of strain. Using arguments from soil mechanics, we find that the dense gouge was initially overconsolidated relative to the equilibrium level, whereas the loose gouge was initially underconsolidated relative to this level. Therefore, the transient stress behavior must be due to the overconsolidated state of the gouge at the new rate when the velocity is increased and to the underconsolidated state when the velocity is lowered. Time-dependent compaction was also shown to cause a transient stress response similar to the velocity-dependent behavior. This may be important in natural fault gouges as they become consolidated and stronger with time. In addition, the strain hardening of the gouge during shearing was found to be a function of velocity, rendering it difficult to quantify the change in equilibrium shear stress when velocity is varied under certain conditions.

Journal of Structural Geology↗
USGS1986

The effects of sliding velocity on the frictional and physical properties of heated fault gouge

The frictional properties of a crushed granite gouge and of gouges rich in montmorillonite, illite, and serpentine minerals have been investigated at temperatures as high as 600??C, confining pressures as high as 2.5 kbar, a pore pressure of 30 bar, and sliding velocities of 4.8 and 4.8??10-2 ??m/sec. The gouges showed nearly identical strength behaviors at the two sliding velocities; all four gouges, however, showed a greater tendency to stick-slip movement and somewhat higher stress drops in the experiments at 4.8??10-2 ??m/sec. Varying the sliding velocity also had an effect on the mineral assemblages and deformation textures developed in the heated gouges. The principal mineralogical difference was that at 400??C and 1 kbar confining pressure a serpentine breakdown reaction occurred in the experiments at 4.8??10-2 ??m/sec but not in those at 4.8 ??m/sec. The textures developed in the gouge layers were in part functions of the gouge type and the temperature, but changes in the sliding velocity affected, among other features, the degree of mineral deformation and the orientation of some fractures. ?? 1986 Birkha??user Verlag.

Pure and Applied Geophysics PAGEOPH↗
USGS1986

Effects of temperature and sliding rate on frictional strength of granite

Layers of artificial granite gouge have been deformed on saw-cut granite surfaces inclined 30?? to the sample axes. Samples were deformed at a constant confining pressure of 250 MPa and temperatures of 22 to 845??C. The velocity dependence of the steady-state coefficient of friction (??ss) was determined by comparing sliding strengths at different sliding rates. The results of these measurements are consistent with those reported by Solberg and Byerlee (1984) at room temperature and Stesky (1975) between 300 and 400??C. Stesky found that the slip-rate dependence of (??ss) increased above 400??C. In the present study, however, the velocity dependence of (??ss) was nearly independent of temperature. ?? 1986 Birkha??user Verlag.

Pure and Applied Geophysics PAGEOPH↗
USGS1986

Stick slip, charge separation and decay

Measurements of charge separation in rock during stable and unstable deformation give unexpectedly large decay times of 50 sec. Time-domain induced polarization experiments on wet and dry rocks give similar decay times and suggest that the same decay mechanisms operate in the induced polarization response as in the relaxation of charge generated by mechanical deformation. These large decay times are attributed to electrochemical processes in the rocks, and they require low-frequency relative permittivity to be very large, in excess of 105. One consequence of large permittivity, and therefore long decay times, is that a significant portion of any electrical charge generated during an earthquake can persist for tens or hundreds of seconds. As a result, electrical disturbances associated with earthquakes should be observable for these lengths of time rather than for the milliseconds previously suggested. ?? 1986 Birka??user Verlag.

Pure and Applied Geophysics PAGEOPH↗
USGS1986

Changes in complex resistivity during creep in granite

A sample of Westerly granite was deformed under constant stress conditions: a pore pressure of 5 MPa, a confining pressure of 10 MPa, and an axial load of 170 MPa. Pore volume changes were determined by measuring the volume of pore fluid (0.01 M KClaq) injected into the sample. After 6 days of creep, characterized by accelerating volumetric stain, the sample failed along a macroscopic fault. Measurements of complex resistivity over the frequency range 0.001-300 Hz, taken at various times during creep, showed a gradual increase in both conductivity and permittivity. When analysed in terms of standard induced polarization (IP) techniques, the changing complex resistivity resulted in systematic changes in such parameters as percent frequency effect and chargeability. These results suggest that it may be possible to monitor the development of dilatancy in the source region of an impending earthquake through standard IP techniques. ?? 1986 Birka??user Verlag.

Pure and Applied Geophysics PAGEOPH↗
USGS1986

Laboratory measurements of velocity-dependent frictional strength

Water levels, location, depths, and aquifers tapped are given for 113 observation wells in Michigan. Tabulated data include extremes of water levels for 1985 and for the period of record, pumpage of most major groundwater users in the state, and water quality data from selected wells. (USGS)

Open-File Report↗