Chapter 7: Late Quaternary fault scarps, mountain-front landforms, and Pliocene-Quaternary segmentation on the range-bounding fault zone, Sangre de Cristo Mountains, New Mexico

1990 ◽  
pp. 131-156 ◽  
Author(s):  
Christopher M. Menges
Keyword(s):  
New Mexico ◽  
Fault Zone ◽  
Late Quaternary ◽  
Mountain Front ◽  
Sangre De Cristo ◽  
Fault Scarps

QUANTIFYING LATE QUATERNARY FAULT MOVEMENT IN THE TEPETATE-BATON ROUGE FAULT ZONE SOUTHEAST LOUISIANA: IMPLICATIONS FOR COASTAL SUBSIDENCE

2016 ◽  
Author(s):  
Torbjörn E. Tornqvist ◽  
◽  
Zhixiong Shen ◽  
Nancye H. Dawers ◽  
Nicole M. Gasparini ◽  
...  
Keyword(s):  
Fault Zone ◽  
Baton Rouge ◽  
Late Quaternary ◽  
Fault Movement

Earthquake Hazard Estimation in Areas of Low Historical Seismicity: A Focus on the Northern Rio Grande Rift, Colorado and New Mexico

1990 ◽  
Vol 6 (4) ◽  
pp. 657-680 ◽  
Author(s):  
Charles E. Glass
Keyword(s):  
New Mexico ◽  
Gaussian Model ◽  
Rio Grande ◽  
Earthquake Hazard ◽  
Weibull Model ◽  
Historical Seismicity ◽  
Rio Grande Rift ◽  
Earthquake Activity ◽  
Sangre De Cristo ◽  
Northern Rio Grande

Estimates of the probability of future earthquake activity are difficult to make in areas where historical seismicity may be low or absent, but where young fault scarps attest to recent or ongoing tectonism. Three non-Poisson models, a Weibull model, a Gaussian model and a lognormal model, are used to estimate the earthquake hazard for one such area, the northern Rio Grande Rift. This portion of the Rio Grande Rift displays numerous Holocene faults attesting to ongoing tectonism, but displays essentially no historical seismicity. The earthquake hazard for the Sangre de Cristo fault zone from Taos, New Mexico to Salida, Colorado calculated using these models is remarkably consistent (probability of at least one Mo = 7 earthquake in the next 50 years ∼ 2.5 × 10−3), with increased hazard for the Sangre de Cristo fault in north San Luis Valley (∼5.0×10−3) and near Taos (∼1.0×10−2) due to the long holding times along these segments.

scholarly journals Seismic Activity of the Manisa Fault Zone in Western Turkey Constrained by Cosmogenic 36Cl Dating

Geosciences ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 451
Author(s):  
Nasim Mozafari ◽  
Çağlar Özkaymak ◽  
Dmitry Tikhomirov ◽  
Susan Ivy-Ochs ◽  
Vasily Alfimov ◽  
...  
Keyword(s):  
Fault Zone ◽  
Normal Fault ◽  
Vertical Displacement ◽  
Historical Records ◽  
Western Turkey ◽  
Slip Rates ◽  
Vertical Displacements ◽  
Surface Ruptures ◽  
Fault Scarps ◽  
Calculated Average

This study reports on the cosmogenic 36Cl dating of two normal fault scarps in western Turkey, that of the Manastır and Mugırtepe faults, beyond existing historical records. These faults are elements of the western Manisa Fault Zone (MFZ) in the seismically active Gediz Graben. Our modeling revealed that the Manastır fault underwent at least two surface ruptures at 3.5 ± 0.9 ka and 2.0 ± 0.5 ka, with vertical displacements of 3.3 ± 0.5 m and 3.6 ± 0.5 m, respectively. An event at 6.5 ± 1.6 ka with a vertical displacement of 2.7 ± 0.4 m was reconstructed on the Mugırtepe fault. We attribute these earthquakes to the recurring MFZ ruptures, when also the investigated faults slipped. We calculated average slip rates of 1.9 and 0.3 mm yr−1 for the Manastır and Mugırtepe faults, respectively.

Frequency and size of quaternary surface ruptures of the pitaycachi fault, northeastern Sonora, Mexico

1988 ◽  
Vol 78 (2) ◽  
pp. 956-978
Author(s):  
William B. Bull ◽  
Philip A. Pearthree
Keyword(s):  
Late Pleistocene ◽  
Volcanic Rocks ◽  
Surface Rupture ◽  
Maximum Slope ◽  
Degradation Rates ◽  
Mountain Front ◽  
Surface Ruptures ◽  
Study Sites ◽  
Fault Scarps ◽  
Prior Event

Abstract Movements along the Pitaycachi fault since the Miocene juxtaposed different alluvial units and created 2- to 45-m-high fault scarps downslope from a pedimented mountain front prior to 1887. In 1887, a major earthquake formed a 75-km-long, 12- to 4-m-high scarp along the trace of prehistoric surface ruptures. Diverse evidence from many study sites indicates that about 200,000 yr elapsed between the prior (youngest Pleistocene) event and the 1887 surface rupture. Cumulative displacements of Pliocene(?) to mid-Pleistocene alluvial fans and stream terraces decrease with decreasing age. The trace of the prior rupture was largely buried by sheets of late Pleistocene and Holocene piedmont alluvium. Late Pleistocene soils are offset about the same amount as the height of the 1887 scarp. Valleys that are as much as 40 m deep and 0.5 to 0.9 km wide have been eroded since the prior event; they contain multiple late Pleistocene and Holocene stream terraces that were not faulted until 1887. Pre-1887 alluvial fault scarps were degraded to 2° to 9° slopes before the 1887 event, even in resistant materials such as clay-rich soil horizons with unweathered rhyolite cobbles and calcrete. Scarp height-maximum slope regressions and diffusion-equation analyses for reconstructed pre-1887 scarp profiles indicate that the prior event occurred more than 100,000 yr ago. Acceleration of scarp degradation rates during the Holocene, and/or relatively resistant materials exposed in the scarps, would increase the age estimates to 200,000 yr or more. Very long recurrence intervals are the characteristic style of movement on the Pitaycachi fault. At one site, six ages of diverse valley fills were inset into pedimented granodiorite upslope from the fault between the prior and 1887 events. Only 3 m of relief remained before the 1887 rupture increased the scarp height from 3 to 6 m. Some hillslopes have triangular talus facets of carbonatecemented colluvium that resulted from infrequent fault movements and intervening periods of erosion. Smooth hillsides of resistant volcanic rocks between the facets show that virtually all of the prior surface-rupture event scarps had been removed by prolonged slope degradation.

scholarly journals Chronology of terraces in the Rio Grande rift, Socorro basin, New Mexico: Implications for terrace formation

Geosphere ◽  
2020 ◽  
Vol 16 (6) ◽  
pp. 1457-1478
Author(s):  
Brad D. Sion ◽  
Fred M. Phillips ◽  
Gary J. Axen ◽  
J. Bruce J. Harrison ◽  
David W. Love ◽  
...  
Keyword(s):  
New Mexico ◽  
Late Quaternary ◽  
Rio Grande ◽  
New Age ◽  
Alluvial Fan ◽  
Rio Grande Rift ◽  
Arid Environments ◽  
Alluvial Deposits ◽  
Continental Scale ◽  
Geomorphic Surfaces

Abstract The Rio Grande rift hosts a remarkable record of Quaternary river incision preserved in an alluvial terrace sequence that has been studied for more than a century. However, our understanding of Rio Grande incision history in central New Mexico since the end of basin filling ca. 0.78 Ma remains hampered by poor age control. Robust correlations among Rio Grande terrace sequences in central and southern New Mexico are lacking, making it difficult to address important process-related questions about terrace formation in continental-scale river systems. We present new age controls using a combination of 40Ar/39Ar, 36Cl surface-exposure, and 14C dating techniques from alluvial deposits in the central New Mexico Socorro area to document the late Quaternary incision history of the Rio Grande. These new age controls (1) provide constraints to establish a firm foundation for Socorro basin terrace stratigraphy, (2) allow terrace correlations within the rift basin, and (3) enable testing of alternative models of terrace formation. We identified and mapped a high geomorphic surface interpreted to represent the end of basin filling in the Socorro area and five distinct, post–Santa Fe Group (ca. 0.78 Ma) alloformations and associated geomorphic surfaces using photogrammetric methods, soil characterization, and stratigraphic descriptions. Terrace deposits exhibit tread heights up to 70 m above the valley floor and are 5 to >30 m thick. Their fills generally have pebble-to-cobble bases overlain by fine-to-pebbly sand and local thin silt and clay tops. Alluvial-fan terraces and associated geomorphic surfaces grade to former valley levels defined by axial terrace treads. Carbon-14 ages from detrital charcoal above and below a buried tributary terrace tread show that the most recent aggradation event persisted until ca. 3 ka during the transition from glacial to modern climate conditions. Drill-log data show widespread valley fill ∼30 m thick that began aggrading after glacial retreat in northern New Mexico and southern Colorado (ca. 14 ka). Aggradation during this transition was likely due to hillslope destabilization, increased sediment yield, decreased runoff, and reduced stream competence. Chlorine-36 ages imply similar controls on earlier terraces that have surface ages of ca. 27–29, 64–70, and 135 ka, and suggest net incision during glacial expansions when increased runoff favored down-cutting and bedload mobilization. Our terrace chronology supports existing climate-response models of arid environments and links tributary responses to the axial Rio Grande system throughout the central Rio Grande rift. The terrace chronology also reflects a transition from modest (60 m/m.y.) to rapid (300 m/m.y.) incision between 610 and 135 ka, similar to patterns observed throughout the Rio Grande rift and the western United States in general.

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