Low‐angle normal fault earthquakes and triggering

Axen, Gary J.

doi:10.1029/1999gl005405

Cited by 59 publications

(44 citation statements)

References 25 publications

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“…However, many normal faults have a listric geometry, and flatten out with depth (e.g., Shelton, 1984;Xiao and Suppe, 1992), even if some seismogenic faults are known to be low-angle normal faults (e.g., Abbott et al, 2001;Abers et al, 1997;Axen, 1999), the mechanism by which they trigger earthquakes is still under debate (e.g., Jackson and White, 1989;Lecomte et al, 2012). As stated above, the dip angles of the main faults in the Weihe graben vary from 40°to 71°, but are mostly N 50°, consistent with the subsurface fault geometry revealed by seismic reflection data (Xie, 2011).…”

Section: Geometric Characteristics Of Active Normal Faultsmentioning

confidence: 98%

Tectonic activity and structural features of active intracontinental normal faults in the Weihe Graben, central China

et al. 2014

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This study examines the tectonic activity and structural features of active normal faults in the Weihe Graben, central China. The Weihe Graben is an area with a high level of historic seismicity, and it is one of the intracontinental systems that developed since Tertiary in the extensional environment around the Ordos Block. Analysis of high-resolution remote-sensing imagery data, field observations, and radiocarbon dating results reveal the following: i) active normal faults are mainly developed within a zone b500 m wide along the southern border of the eastern part of the Weihe Graben; ii) the active faults that have been identified are characterized by stepwise fault scarps dipping into the graben at angles of 40°-71°; iii) there are numerous discontinuous individual fault traces, ranging in length from a few tens of meters to 450 m (generally b 200 m); iv) fault zone structures, topographic features, and fault striations on the main fault planes indicate almost pure normal-slip; and v) late Pleistocene-Holocene terrace risers, loess, and alluvial deposits have been vertically offset by up to~80 m, with a non-uniform dip-slip rate (throw-rates) ranging from~2.1 to 5.7 mm/yr, mostly 2-3 mm/yr. Our results reveal that active normal faults have been developing in the Weihe Graben under an ongoing extensional environment, probably associated with the pre-existing graben and spreading of the continental crust, and this is in contrast with the Ordos Block and neighboring orogenic regions. These results provide new insights into the nature of extensional tectonic deformation in intracontinental graben systems.

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Section: Geometric Characteristics Of Active Normal Faultsmentioning

confidence: 98%

Tectonic activity and structural features of active intracontinental normal faults in the Weihe Graben, central China

et al. 2014

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“…Assuming that the z bdt is the deepest tip of the activation of a normal fault, the corresponding seismogenic volume (V) depends on the fault dip angle (α) and the lateral extent of the fault (L). In fact, low-angle normal fault rarely generates significant magnitude earthquakes (e.g., Axen, 1999), if any. A volume shape ratio L = 3•z is considered as proposed in Doglioni et al (2015b).…”

Section: Maximum Seismogenic Isovolumes Of Italymentioning

confidence: 99%

Graviquakes in Italy

et al. 2015

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“…There is now widespread agreement that many detachment faults were active at very low angles, even though the mechanics of such movement is still not well understood (e.g., Wernicke, 1981Wernicke, , 1995Rey nolds and Spencer, 1985;John, 1987a;Spencer and Chase, 1989;John and Foster, 1993;Axen, 1999). However, the details of detachment-fault movement histories have received little attention in the literature.…”

Section: Introductionmentioning

confidence: 95%

Late-stage evolution of the Chemehuevi and Sacramento detachment faults from apatite (U-Th)/He thermochronometry--Evidence for mid-Miocene accelerated slip

Carter

Kohn

Foster

et al. 2006

Geological Society of America Bulletin

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The unique low-temperature sensitivity of the apatite (U-Th)/He (AHe) technique provides valuable new information relating to the late-stage thermal evolution of metamorphic core complexes in the southern Basin and Range Province. In all the ranges studied, the data show greater complexity than previously seen from other thermochronometers. In the Chemehuevi and northern Sacramento Mountains, a trend of decreasing ages toward the northeast applies only for the structurally shallowest parts of the footwall. This is followed by essentially age-invariant segments of 15 ± 1 Ma, refl ecting an increase in the rate of detachment fault movement. The timing of the change suggested by the data agrees with recently published AHe results from the nearby Harcuvar Mountains, located ~125 km to the southeast, suggesting that an underlying regional mechanism triggered this change. Plate reconstructions indicate that the Pioneer-Mendocino fracture zone migrated northward through the area at this time, leaving a slab window in its wake. We suggest that the additional heat applied to the base of the lithosphere from the slab window resulted in mechanical weakening of the area and that this, combined with the extensional strain regime present, resulted in an increased rate of slip within the actively extending metamorphic core complexes. This agrees well with timing constraints for extension onset in the central Basin and Range Province of southern Nevada, and suggests that weakening of the southern Basin and Range Province at 15 ± 1 Ma was partially responsible for the onset of extension in the central Basin and Range. These fi ndings demonstrate that improved constraints on changes in extension rate within the Basin and Range Province should be possible through the application of the AHe technique to other metamorphic core complex footwalls.Keywords: metamorphic core complexes, Basin and Range Province, low-angle normal faults, (U-Th)/He, low-temperature thermochronology.

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Low‐angle normal fault earthquakes and triggering

Cited by 59 publications

References 25 publications

Tectonic activity and structural features of active intracontinental normal faults in the Weihe Graben, central China

Tectonic activity and structural features of active intracontinental normal faults in the Weihe Graben, central China

Graviquakes in Italy

Late-stage evolution of the Chemehuevi and Sacramento detachment faults from apatite (U-Th)/He thermochronometry--Evidence for mid-Miocene accelerated slip

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