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Fault (geology)

About: Fault (geology) is a research topic. Over the lifetime, 26732 publications have been published within this topic receiving 744535 citations.


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Journal ArticleDOI
TL;DR: In this article, it was shown that cataclastic fabric with fractal dimensions D V2.7 is preferred for slip localisation in narrow shear bands in carbonate faults.

180 citations

Journal ArticleDOI
13 Sep 2002-Science
TL;DR: Interferometric Synthetic Aperture Radar observations of surface deformation due to the 1999 Hector Mine earthquake reveal motion on several nearby faults of the eastern California shear zone, indicating that the latter are mechanically distinct from the ambient crustal rocks.
Abstract: Interferometric Synthetic Aperture Radar observations of surface deformation due to the 1999 Hector Mine earthquake reveal motion on several nearby faults of the eastern California shear zone. We document both vertical and horizontal displacements of several millimeters to several centimeters across kilometer-wide zones centered on pre-existing faults. Portions of some faults experienced retrograde (that is, opposite to their long-term geologic slip) motion during or shortly after the earthquake. The observed deformation likely represents elastic response of compliant fault zones to the permanent co-seismic stress changes. The induced fault displacements imply decreases in the effective shear modulus within the kilometer-wide fault zones, indicating that the latter are mechanically distinct from the ambient crustal rocks.

180 citations

Journal ArticleDOI
TL;DR: A micro-earthquake experiment in the median valley of the Mid-Atlantic Ridge near 23°N in 1982 is used to measure earthquake source parameters, to determine the laterally heterogeneous seismic velocity structure across the inner floor, and to develop a kinematic tectonic model for this portion of the Median valley.
Abstract: Data from a microearthquake experiment in the median valley of the Mid-Atlantic Ridge near 23°N in 1982 are used to measure earthquake source parameters, to determine the laterally heterogeneous seismic velocity structure across the inner floor, and to develop a kinematic tectonic model for this portion of the median valley. Fifty-three microearthquakes occurred over a 10-day period beneath the median valley inner floor and eastern rift mountains. Twenty of 23 well-located inner floor epicenters define a line of activity, about 17 km long, having a strike of N25°E and located near an along-axis depression some 300–400 m deeper than surrounding regions. Earthquakes with well-resolved hypocenters generally have focal depths of 4–8 km beneath the seafloor of both the inner floor and the rift mountains; the hypocentral locations are robust with respect to plausible lateral variations in seismic velocity structure. Composite fault plane solutions for inner floor events indicate normal faulting on planes dipping at angles near 45°. Normal faulting mechanisms, although poorly constrained, are also indicated for the rift mountain microearthquakes. Seismic moments, approximate fault dimensions, and average stress drops for the largest events recorded are 1019–1020 dyn cm, 200–400 m, and 1–70 bars, respectively. A twodimensional tomographic inversion of P wave travel time residuals from microearthquakes and local shots indicates a well-resolved lateral heterogeneity in crustal velocity structure across the median valley inner floor. P wave velocities at 1–5 km depth within a zone less than 10 km wide beneath the central inner floor are lower by several percent than in surrounding regions. The most likely explanation for the low velocities is that the region is the site of the most recent local magmatic injection and remains pervasively fractured as a result of rapid hydrothermal quenching of the newly emplaced crustal column. By this view, the seismic velocity structure at the ridge axis evolves, probably by the sealing of cracks and pores, within the first few hundred thousand years of crustal accretion. Consideration of the detailed Sea Beam bathymetry in this region of the inner floor, the characteristics of large earthquakes that the region has experienced during the past 25 years, and the results of the microearthquake and tomography analysis suggests that this section of the median valley has been undergoing continued horizontal extension and block faulting without significant crustal injection of magma for at least the past 104 years.

180 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the deep structure of Etna and its Ionian margin and found that a volume of high velocity material is found in a structurally high position; the emplacement of this suggests spreading of the surrounding medium.

179 citations

Journal ArticleDOI
TL;DR: In this article, structural and physiographic features of the 1200 km-long Philippine fault zone are fully as spectacular as those of the better-known San Andreas and Alpine faults, and current activity is indicated by many localities in which scarps cut Recent gravels.
Abstract: Conflicting views of circum-Pacific tectonics have focused on the Philippines-Taiwan 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 of the better-known San Andreas and Alpine faults, and current activity is indicated by many localities in which scarps cut Recent gravels. Predominance of horizontal over vertical displacements is indicated by linearity of the fault trace, failure of one side to be consistently higher than the other, disregard for gross physiography, and scissoring of individual scarps within the zone. Consistent stream offsets on Luzon, Masbate, and Leyte demonstrate unequivocally that the sense of Recent displacement has been uniformly sinistral (left-handed). The Philippine fault has no obvious geologic relationship to active volcanoes, but the parallelism and proximity of the fault to the Mindanao trench suggest a close causal relationship. The remarkable Longitudinal Valley of eastern Taiwan represents another great transcurrent fault parallel to the western Pacific rim, and ground displacements during historic earthquakes indicate a sinistral sense of displacement here as well as in the adjacent Philippines. This study does not support the hypothesis of counterclockwise rotation of the Pacific basin, but more important is the further documentation of the predominance of transcurrent faulting in active circum-Pacific orogenic areas. These results reinforce earlier field studies in Alaska, California, Chile, and New Zealand, as well as emphasizing the geological reasonability of the results of seismic fault-plane solutions indicating the world-wide predominance of transcurrent movements.

179 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20242
20234,903
202210,233
20211,417
2020998
2019966