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Departamento de Geodinámica, Universidad Complutense de Madrid, Spain
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- PublicationOpen AccessEffects of repeated paleoearthquakes on the Alhama de Murcia Fault (Betic Cordillera, Spain) on the Quaternary evolution of an alluvial fan system(2003)
; ; ; ; ;Martínez-Díaz, J. J.; Departamento de Geodinámica, Universidad Complutense de Madrid, Spain ;Masana, E.; Departamento de Geologia Dinàmica i Geofísica, Universitat de Barcelona, Spain ;Hernández-Enrile, J. L.; Departamento de Geodinámica, Universidad Complutense de Madrid, Spain ;Santanach, P.; Departamento de Geologia Dinàmica i Geofísica, Universitat de Barcelona, Spain; ; ; In this work we present a study of an alluvial fan system, which is affected by the Quaternary activity of the leftlateral, reverse Alhama de Murcia Fault (Betic Cordillera). Paleoseismic studies in this area yield data that can be compared and correlated with the morphologic and tectono-sedimentary evolution of the alluvial fan. The spatial arrangement of the sedimentary alluvial fan units near the fault zone, shown in trenches, is controlled by the recurrent reverse, left-lateral coseismic events. We analysed the morphology of the drainage network using a 1:5000 scale orthoimage to identify and measure horizontal deflections along the fault. The channel pattern analysis allowed us to estimate the average horizontal slip rate of the SAMF for the last 130 ka. This value is 0.21 mm/a, which is slightly higher than the range of values obtained by trenching analysis for the last 30 ka, (0.06 to 0.15 mm/yr). The interpretation of the stratigraphic sequence exposed along the trench walls constrained the occurrence of at least two surface faulting earthquakes during the last 30000 years. The most recent event happened after the El Saltador Creek dissected the alluvial fan. The penultimate event occurred while the alluvial fan was still active.910 357 - PublicationRestrictedRevised slip rates for the Alpine fault at Inchbonnie: Implications for plate boundary kinematics of South Island, New Zealand(2010-05-25)
; ; ; ; ; ; ;Langridge, R. M.; GNS SCIENCE, P.O. BOX 30-368, LOWER HUTT 5010, NEW ZEALAND ;Villamor, P.; GNS SCIENCE, P.O. BOX 30-368, LOWER HUTT 5010, NEW ZEALAND ;Basili, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Almond, P.; DEPARTMENT OF SOIL SCIENCE, P.O. BOX 84, LINCOLN UNIVERSITY, LINCOLN 7647, CANTERBURY, NEW ZEALAND ;Martinez-Diaz, J. J.; DEPARTAMENTO DE GEODINÁMICA, FACULTAD DE CIENCIAS GEOLÓGICAS, UNIVERSIDAD COMPLUTENSE DE MADRID, MADRID 28040, SPAIN ;Canora, C.; DEPARTAMENTO DE GEODINÁMICA, FACULTAD DE CIENCIAS GEOLÓGICAS, UNIVERSIDAD COMPLUTENSE DE MADRID, MADRID 28040, SPAIN; ; ; ; ; The northeast-striking, dextral-reverse Alpine fault transitions into the Marlborough Fault System near Inchbonnie in the central South Island, New Zealand. New slip-rate estimates for the Alpine fault are presented following a reassessment of the geomorphology and age of displaced late Holocene alluvial surfaces of the Taramakau River at Inchbonnie. Progressive avulsion and abandonment of the Taramakau floodplain, aided by fault movements during the late Holocene, have preserved a left-stepping fault scarp that grows in height to the northeast. Surveyed dextral (22.5 ± 2 m) and vertical (4.8 ± 0.5 m) displacements across a left stepover in the fault across an alluvial surface are combined with a precise maximum age from a remnant tree stump (≥1590–1730 yr) to yield dextral, vertical, and reverse-slip rates of 13.6 ± 1.8, 2.9 ± 0.4, and 3.4 ± 0.6 mm/yr, respectively. These values are larger (dextral) and smaller (dip slip) than previous estimates for this site, but they refl ect advances in the local chronology of surfaces and represent improved time-averaged results over 1.7 k.y. A geological kinematic circuit constructed for the central South Island demonstrates that (1) 69%–89% of the Australian-Pacific plate motion is accommodated by the major faults (Alpine-Hope-Kakapo) in this transitional area, (2) the 50% drop in slip rate on the Alpine fault between Hokitika and Inchbonnie is taken up by the Hope and Kakapo faults at the southwestern edge of the Marlborough Fault System, and (3) the new slip rates are more compatible with contemporary models of strain partitioning presented from geodesy.225 37