Discovery of the Baldy toreva near urban areas along the southern Wasatch Range, Utah

2020 ◽  
Vol 55 (1) ◽  
pp. 55-73
Author(s):  
Eric R. Meyer ◽  
Ron A. Harris
Keyword(s):  
Urban Areas ◽  
Normal Fault ◽  
Single Event ◽  
Mass Wasting ◽  
Geologic Hazard ◽  
Slide Block ◽  
Mountain Front ◽  
Wasatch Front ◽  
Prominent Peak

ABSTRACT Structural and geomorphic studies, and lithostratigraphic and biostratigraphic mapping reveal that a giant toreva block (6.125 km3) slid off Mount Timpanogos toward what are now densely populated urban areas along the Wasatch Front of Utah. The block forms a prominent peak known as Big Baldy, which consists of steeply dipping and locally brecciated limestone and quartzarenite over nearly horizontal shale. Preferential erosion of this shale below overlying limestone and quartzarenite cliffs is most likely the cause of this particular landslide and potential future slides along the Wasatch Front. The low-angle contact at the base of the giant toreva block was initially mapped as a thrust, then as a low-angle normal fault. In both cases, these faults were inferred to have large amounts of displacement (900 meters), but no traces of such faults are found in adjacent canyons. The Baldy slide is associated with geomorphologic features, such as faceted spurs, landslide scarps, sackungen, and hummocky terrain. Limestone and quartzarenite beds in the block are back-rotated up to 80° and are locally broken and brecciated. No evidence of hydro-fracturing is found in the breccia or of multiple brecciation episodes, which indicates surficial rather than deep-crustal processes and perhaps a single event of slip. We speculate based on structural reconstructions of the slide block, and interpolation of maximum downcutting rates on nearby streams, that the slide initiated between 700 and 500 ka. Discovery of the Baldy slide attests to the importance of recognizing the influence of surficial processes in mountain front development and demonstrate the ongoing geologic hazard of mass wasting to communities along the seismically active Wasatch Front and similar horst blocks.

scholarly journals Late Quaternary faulting in southern Matese (central Italy): implications for earthquake potential in the southern Apennines

2021 ◽  
Author(s):  
Paolo Boncio ◽  
Eugenio Auciello ◽  
Vincenzo Amato ◽  
Pietro Aucelli ◽  
Paola Petrosino ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Central Italy ◽  
Slip Rate ◽  
Normal Fault ◽  
Historical Earthquakes ◽  
Fault System ◽  
Southern Apennines ◽  
Mountain Front ◽  
Point Data ◽  
Earthquake Potential

Abstract. We studied in detail the Gioia Sannitica active normal fault (GF) along the Southern Matese Fault system in the southern Apennines of Italy. The current activity of the fault system and its potential to produce strong earthquakes have been underestimated so far, and are now defined. Precise mapping of the GF fault trace on a 1 : 20,000 geological map and several point data on geometry, kinematics and throw rate are made available in electronic format. The GF, and in general the entire fault system along the southern Matese mountain front, is made of slowly-slipping faults, with a long active history revealed by the large geologic offsets, mature geomorphology, and complex fault pattern and kinematics. Present activity has resulted in Late Quaternary fault scarps resurrecting the foot of the mountain front, and Holocene surface faulting. The slip rate varies along-strike, with maximum Late Pleistocene – Holocene throw rate of ~0.5 mm/yr. Activation of the 11.5 km-long GF can produce up to M 6.1 earthquakes. If activated together with the 18 km-long Ailano-Piedimonte Matese fault (APMF), the seismogenic potential would be M 6.8. The slip history of the two faults is compatible with a contemporaneous rupture. The observed Holocene displacements on the GF and APMF are compatible with activations during some poorly known historical earthquakes, such as the 1293 (M 5.8), 1349 (M 6.8; southern prolongation of the rupture on the Aquae Iuliae fault?) and CE 346 earthquakes. A fault rupture during the 847 poorly-constrained historical earthquake is also compatible with the dated displacements.

scholarly journals Past earthquake timing and magnitude along the Inglewood fault, Taranaki, New Zealand

1994 ◽  
Vol 27 (2) ◽  
pp. 155-162 ◽  
Author(s):  
A. G. Hull
Keyword(s):  
Volcanic Ash ◽  
Surface Displacement ◽  
Normal Fault ◽  
Historical Earthquakes ◽  
Normal Faults ◽  
Single Event ◽  
Ground Shaking ◽  
Large Earthquakes ◽  
Fault Length ◽  
Strong Ground

Several active normal faults in the onshore and offshore regions of Taranaki are capable of generating large earthquakes and associated strong ground shaking. Historical earthquakes are concentrated offshore of Cape Egmont, and no significant earthquakes have been detected along the major onshore surface faults. The northeaststriking Inglewood fault is a major onshore, southward-dipping normal fault. It has a known length of c. 20 km and an average scarp height of c. 3 m on landforms less than about 15,000 yrs old. Three subsurface excavations at two sites along the Inglewood fault about 15 km from New Plymouth have revealed three surface fault displacements during the last c. 13,000 years. Earthquakes resulting in about 1.2 m of surface displacement occurred at c. 3,500 radiocarbon yrs BP; between 4,000 and 9,000 radiocarbon yrs BP; and between 10,000 and 13,000 radiocarbon yrs BP, judged by the amount of vertical offset of dated volcanic ash layers. Based on average single-event fault slip values of 1.2-3.0 m and a fault length of 20-30 km, the estimated earthquake magnitudes associated with these past movements range from Mw 6.7 to 7.2.

Quantifying submarine mass-wasting and links to seismicity along the Roseau normal fault, Lesser Antilles

2020 ◽  
Author(s):  
Alex Hughes ◽  
Javier Escartín ◽  
Jean-Arthur Olive ◽  
Jeremy Billant ◽  
Christine Deplus ◽  
...  
Keyword(s):  
Sedimentary Cover ◽  
Hanging Wall ◽  
Normal Fault ◽  
Oceanic Lithosphere ◽  
Fault Scarp ◽  
Lesser Antilles ◽  
Mass Wasting ◽  
Erosion And Deposition ◽  
First Order ◽  
Mass Balancing

<p>At the scale of individual faults, few studies have investigated fundamental interactions between active faulting, erosion, and deposition in submarine landscapes dominated by magmatic and volcaniclastic deposits with thin sedimentary cover. Such landscapes comprise a high percentage of the global seafloor. Therefore, there is a significant gap in our understanding of first-order processes of erosion and deposition for a large portion of the Earth’s surface. The paucity of studies derives mainly from challenges involved in the acquisition of high-resolution bathymetry and seafloor data in a deep-marine environment. In this study, we use bathymetry data obtained with autonomous deep-sea vehicles and processed to obtain a 1-m resolution digital elevation model along the active Roseau normal fault, in the Lesser Antilles volcanic arc. The Roseau fault was the source of the 2004 M<sub>w</sub>6.3 Les Saintes earthquake, and M<sub>w </sub>5-6 events are thought to occur on the Roseau fault every few thousand years. Building on the work of Vilaseca (MSc Thesis, 2015), we quantify the height, slope, and volume eroded from a well-defined fault scarp created by the Roseau fault and calculate volumes for a series of erosional footwall catchments developed in the scarp. We also quantify the volume and morphology of a series of dejection cones in the hanging wall of the Roseau fault to facilitate mass-balancing between the hanging wall and footwall of the scarp.</p><p> </p><p>Mass-balancing indicates that in isolated basins, where the primary supply of sediment is from the adjacent footwall scarp, dejection cone volumes are around half of the total volume of material eroded from the individual footwall catchments. Geomorphological analyses show that dejection cones have surface slopes as high as 30°and form as radial depositional features adjacent to catchment outlets. The results of the mass-balancing, the high slope values for the cone surface, and the identification of >1 m sized blocks of eroded material present on the cone surfaces indicate that dejection cones form through episodic, coseismic and/or post-seismic, gravitationally driven mass-wasting of the uplifting footwall scarp. Preliminary morphometric analysis of the Roseau fault scarp potentially indicates that erosion of normal fault scarps in volcaniclastic and magmatic deposits may primarily occur beyond a threshold in fault scarp height between ~40­­–70 m. Above ~40–70 m height, erosional catchments may begin to develop on the footwall scarp and average scarp slope decreases with increasing scarp height until average slope values reach an equilibrium of ~35°. The quantitative survey of the Roseau fault scarp in this study demonstrates that episodic earthquake-related mass-wasting is a key erosional process for volcanic and sedimentary deposits in submarine landscapes. Furthermore, the results presented here will be used as first-order inputs to develop models of seafloor erosion and apply them to understand submarine landscape evolution of the oceanic lithosphere.</p>

scholarly journals Pliocene to Quaternary tectonics in the Horná Nitra Depression (Western Carpathians)

2011 ◽  
Vol 62 (4) ◽  
pp. 381-393 ◽  
Author(s):  
Rastislav Vojtko ◽  
Juraj Beták ◽  
Jozef Hók ◽  
František Marko ◽  
Vojtech Gajdoš ◽  
...  
Keyword(s):  
Active Fault ◽  
Slip Rate ◽  
Normal Fault ◽  
Western Carpathians ◽  
Early Pleistocene ◽  
Tectonic Activity ◽  
Slip Rates ◽  
Compressional Stress ◽  
Mountain Front ◽  
Half Graben

Pliocene to Quaternary tectonics in the Horná Nitra Depression (Western Carpathians)The Horná Nitra Depression is an Upper Miocene-Quaternary intramontane sedimentary basin. This N-S elongated half-graben structure is rimmed from the west by the marginal Malá Magura fault which is the most distinctive fault in the Horná Nitra Depression, traditionally considered as an active fault during the neotectonic phase. This dislocation is attended by contrasting landforms and their parameters. The lowS-indexof about 1.10, at least two generations of well-preserved faceted slopes along this fault, and longitudinal river valley profiles point to the presence of a low-destructed actual mountain front line, which is typical for the Quaternary active fault systems. Comparison with known normal fault slip rates in the world makes it possible to set an approximate vertical slip rate between 0.3-1.1 m · kyr-1. The present-day fault activity is considered to be normal, steeply dipping towards the east according to structural and geophysical data. The NNW-SSE present-day tectonic maximum horizontal compressional stressSHand perpendicular minimum horizontal compressional stressShwas estimated in the Horná Nitra region. The Quaternary activity of the Malá Magura fault is characterized by irregular movement. Two stages of important tectonic activity along the fault were distinguished. The first stage was dated to the Early Pleistocene. The second stage of tectonic activity can by dated to the Late Pleistocene and Holocene. The Malá Magura fault is permeable for gases because the soil atmosphere above the ca. 150 meters wide fault zone contains increased contents of methane and radon.

scholarly journals Preliminary geologic, geomorphologic and geophysical studies for the paleoseismological analysis of the Amer fault (NE Spain)

2001 ◽  
Vol 80 (3-4) ◽  
pp. 243-253 ◽  
Author(s):  
J. Fleta ◽  
P. Santanach ◽  
X. Goula ◽  
P. Martínez ◽  
B. Grellet ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Slip Rate ◽  
Normal Fault ◽  
Alluvial Fans ◽  
Drainage Basins ◽  
Mountain Front ◽  
Order Of Magnitude ◽  
Wine Glass ◽  
Fault Slip Rate ◽  
Fault Scarps

AbstractThe Amer fault is a 30 km long normal fault, which generated the damaging earthquakes of March and May 1427. Triangular facets, wine glass drainage basins, alluvial fans and scarps along the Amer fault mountain front provide evidence of its recent activity. Topographic profiling, electrical logging, tomographic and high-resolution seismic profiling along the northern segment of the Amer fault showed the following: i) no evidence of surface deformation in recent deposits; ii) fault scarps produced by the Amer fault located only on old alluvial fans, probably Pleistocene in age, and iii) Amer fault related deformation reaching upper Quaternary levels, but not the uppermost horizons. The high sedimentation rate (nearly one order of magnitude greater than the fault slip rate) due to the filling of the lake, which resulted from the damming of the Fluvià river by the Bosc de Tosca lava flow (17,000 yr BP), can account for the absence of surface deformation on Holocene sediments.

scholarly journals Morphotectonic properties of the Lo River Fault near Tam Dao in North Vietnam

2001 ◽  
Vol 1 (1/2) ◽  
pp. 15-22 ◽  
Author(s):  
N. Q. Cuong ◽  
W. A. Zuchiewicz
Keyword(s):  
Normal Fault ◽  
Class I ◽  
Tectonic Activity ◽  
Strong Earthquakes ◽  
The Past ◽  
The Future ◽  
Mountain Front ◽  
North Vietnam

Abstract. The Lo River fault near Tam Dao, North Vietnam, is a young, right-lateral, normal fault which has been active throughout the Quaternary. Rates of dextral slip range between 1 and 2 mm/yr whereas rates of uplift can be estimated roughly at 0.1–1 mm/yr. The drainage deflection and arrangement of shutter ridges suggest 1.5–2.0 km of dextral offset during the past 1–2 millions of years (m. y.), and the height of the youngest faceted spurs averages at 170 m. Analysis of morphometric parametres of the mountain front at Tam Dao indicates that this segment shows properties typical for nearly rectilinear, young normal scarps that belong to class I or II of relative tectonic activity and that are capable of generating strong earthquakes in the future.

Management of minor ailments in primary schoolchildren in rural and urban areas

1996 ◽  
Vol 22 (3) ◽  
pp. 167-174
Author(s):  
J A Cantrill ◽  
B Johannesson ◽  
M Nicholson ◽  
P R Noyce
Keyword(s):  
Urban Areas ◽  
Rural And Urban Areas ◽  
Rural And Urban ◽  
Primary Schoolchildren ◽  
Minor Ailments
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