scholarly journals Development of surface ruptures by hanging-wall extension over a thrust ramp along the Ragged Mountain fault, Katalla, Alaska, USA: Applications of high-resolution three-dimensional terrain models

Geosphere ◽  
2021 ◽  
Author(s):  
Sarah N. Heinlein ◽  
Terry L. Pavlis ◽  
Ronald L. Bruhn
Keyword(s):  
High Resolution ◽  
Hanging Wall ◽  
Three Dimensional ◽  
Active Tectonics ◽  
Normal Fault ◽  
Fault Slip ◽  
The South ◽  
The North ◽  
Terrain Models ◽  
Surface Ruptures

High-resolution three-dimensional terrain models are used to evaluate the Ragged Mountain fault kinematics (Katalla, Alaska, USA). Previous studies have produced contradictory interpretations of the fault’s kinematics because surface ruptures along the fault are primarily steeply dipping, uphill-facing normal fault scarps. In this paper, we evaluate the hypothesis that these uphill-facing scarps represent extension above a buried thrust ramp. Detailed geomorphic mapping along the fault, using 20-cm-resolution aerial imagery draped onto a 1-m-resolution lidar (light detection and ranging) elevation model, was used to produce multiple topographic profiles. These profiles illustrate scarp geometries and prominent convex-upward topographic surfaces, indicating significant disturbance by active tectonics. A theoretical model is developed for fault-parallel flow over a thrust ramp that shows the geometric relationships between thrust displacement, upper-plate extension, and ramp dip. An important prediction of the model for this study is that the magnitude of upper-plate extension is comparable to, or greater than, the thrust displacement for ramps with dips greater than ~45°. This model is used to analyze profile shapes and surface displacements in Move software (Midland Valley Ltd.). Analyses of scarp heights allow estimates of hanging-wall extension, which we then use to estimate slip on the underlying thrust via the model. Assuming a low-angle (30°) uniformly dipping thrust and simple longitudinal extension via normal faulting, variations in extension along the fault would require a slip gradient from ~8 m in the north to ~22 m in the south. However, the same north-south variation in extension with a constant slip of 8–10 m may infer an increase in fault dip from ~30° in the north to ~60° in the south. This model prediction has broader implications for active-fault studies. Because the model quantifies relationships between hanging-wall extension, fault slip, and fault dip, it is possible to invert for fault slip in blind thrust ramps where hanging-wall extension is the primary surface manifestation. This study, together with results from the St. Elias Erosion and Tectonics Project (STEEP), clarifies the role of the Ragged Mountain fault as a contractional structure within a broadly sinistral shear system in the western syntaxis of the St. Elias orogeny.

scholarly journals Supplemental Material: Development of surface ruptures by hanging-wall extension over a thrust ramp along the Ragged Mountain fault, Katalla, Alaska, USA: Applications of high-resolution three-dimensional terrain models

2020 ◽  
Author(s):  
S.N. Heinlein ◽  
et al.
Keyword(s):  
High Resolution ◽  
Digital Elevation Model ◽  
Hanging Wall ◽  
Three Dimensional ◽  
Lidar Data ◽  
Material Development ◽  
Terrain Models ◽  
Digital Elevation ◽  
Surface Ruptures ◽  
Elevation Model

<div>Video S1: Grayscale digital elevation model generated from high-resolution lidar data illustrating surface expressions at the 1 m to tens of meters scale. Video S2: False-color digital elevation model generated from high-resolution lidar data illustrating surface expressions at the 1 m to tens of meters scale.<br></div>

scholarly journals Supplemental Material: Development of surface ruptures by hanging-wall extension over a thrust ramp along the Ragged Mountain fault, Katalla, Alaska, USA: Applications of high-resolution three-dimensional terrain models

2020 ◽  
Author(s):  
S.N. Heinlein ◽  
et al.
Keyword(s):  
High Resolution ◽  
Digital Elevation Model ◽  
Hanging Wall ◽  
Three Dimensional ◽  
Lidar Data ◽  
Material Development ◽  
Terrain Models ◽  
Digital Elevation ◽  
Surface Ruptures ◽  
Elevation Model

<div>Video S1: Grayscale digital elevation model generated from high-resolution lidar data illustrating surface expressions at the 1 m to tens of meters scale. Video S2: False-color digital elevation model generated from high-resolution lidar data illustrating surface expressions at the 1 m to tens of meters scale.<br></div>

scholarly journals Morphotectonic Analysis along the Northern Margin of Samos Island, Related to the Seismic Activity of October 2020, Aegean Sea, Greece

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 102
Author(s):  
Paraskevi Nomikou ◽  
Dimitris Evangelidis ◽  
Dimitrios Papanikolaou ◽  
Danai Lampridou ◽  
Dimitris Litsas ◽  
...  
Keyword(s):  
Fault Zone ◽  
Seismic Activity ◽  
Volcanic Rocks ◽  
Active Tectonics ◽  
Normal Fault ◽  
Aegean Sea ◽  
Northern Margin ◽  
The North ◽  
Eastern Aegean ◽  
Half Graben

On 30 October 2020, a strong earthquake of magnitude 7.0 occurred north of Samos Island at the Eastern Aegean Sea, whose earthquake mechanism corresponds to an E-W normal fault dipping to the north. During the aftershock period in December 2020, a hydrographic survey off the northern coastal margin of Samos Island was conducted onboard R/V NAFTILOS. The result was a detailed bathymetric map with 15 m grid interval and 50 m isobaths and a morphological slope map. The morphotectonic analysis showed the E-W fault zone running along the coastal zone with 30–50° of slope, forming a half-graben structure. Numerous landslides and canyons trending N-S, transversal to the main direction of the Samos coastline, are observed between 600 and 100 m water depth. The ENE-WSW oriented western Samos coastline forms the SE margin of the neighboring deeper Ikaria Basin. A hummocky relief was detected at the eastern margin of Samos Basin probably representing volcanic rocks. The active tectonics characterized by N-S extension is very different from the Neogene tectonics of Samos Island characterized by NE-SW compression. The mainshock and most of the aftershocks of the October 2020 seismic activity occur on the prolongation of the north dipping E-W fault zone at about 12 km depth.

Evolution of Titan’s stratosphere with Cassini/CIRS

2021 ◽  
Author(s):  
Athena Coustenis ◽  
Donald Jennings ◽  
Richard Achterberg ◽  
Panayotis Lavvas ◽  
Conor Nixon ◽  
...  
Keyword(s):  
High Resolution ◽  
Chemical Species ◽  
Far Infrared ◽  
Organic Content ◽  
Large Temperature ◽  
Neutral Atmosphere ◽  
South Pole ◽  
The South ◽  
The North ◽  
Cassini Mission

&lt;p&gt;Titan is a unique body in the solar system in particular because of its earth-like surface features, its putative undersurface liquid water ocean and its large organic content in the atmosphere and on the surface . These chemical species evolve with season, as Titan follows Saturn in its orbit around the Sun with an inclination of about 27&amp;#176;. We performed an analysis of spectra acquired by Cassini/CIRS at high resolution covering the range from 10 to 1500 cm&lt;sup&gt;-1&lt;/sup&gt; since the beginning and until the last flyby of Titan in 2017 and describe the temperature and composition variations ([1-3]. By applying our radiative transfer code (ARTT) to the high-resolution CIRS spectra we study the stratospheric evolution over almost two Titan seasons [1,2]. CIRS nadir and limb spectral together show variations in temperature and chemical composition in the stratosphere during the Cassini mission, before and after the Northern Spring Equinox (NSE) and also during one Titan year.&lt;/p&gt;&lt;p&gt;Since the 2010 equinox we have thus reported on monitoring of Titan&amp;#8217;s stratosphere near the poles and in particular on the observed strong temperature decrease and compositional enhancement above Titan&amp;#8217;s southern polar latitudes since 2012 and until 2014 of several trace species, such as complex hydrocarbons and nitriles, which were previously observed only at high northern latitudes. This effect followed the transition of Titan&amp;#8217;s seasons from northern winter in 2002 to northern summer in 2017, while at that latter time the southern hemisphere was entering winter.&lt;/p&gt;&lt;p&gt;Our data show a continued decrease of the abundances which we first reported to have started in 2015. The 2017 data we have acquired and analyzed here are important because they are the only ones recorded since 2014 close to the south pole in the far-infrared nadir mode at high resolution. A large temperature increase in the southern polar stratosphere (by 10-50 K in the 0.5 mbar-0.05 mbar pressure range) is found and a change in the temperature profile&amp;#8217;s shape. The 2017 observations also show a related significant decrease in most of the abundances which must have started sometime between 2014 and 2017 [3]. In our work, we show that the equatorial latitudes remain rather constant throughout the Cassini mission.&lt;/p&gt;&lt;p&gt;We have thus shown that the south pole of Titan is now losing its strong enhancement, while the north pole also slowly continues its decrease in gaseous opacities. It would have been interesting to see when this might happen, but the Cassini mission ended in September 2017. Perhaps future ground-based measurements and the Dragonfly mission can pursue this investigation and monitor Titan&amp;#8217;s atmosphere to characterize the seasonal events. Our results set constraints on GCM and photochemical models.&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;&amp;#160;[1] Coustenis et al., 2016, Icarus 270, 409-420; [2] Coustenis et al., 2018, Astroph. J., Lett., 854, no2; [3] Coustenis et al., 2020. Titan&amp;#8217;s neutral atmosphere seasonal variations up to the end of the Cassini mission. Icarus 344, 113413. https://doi.org/10.1016/j.icarus.2019.113413.&lt;/p&gt;

Zircon U–Pb geochronology of the Zanhuang metamorphic complex: reappraisal of the Palaeoproterozoic amalgamation of the Trans-North China Orogen

2013 ◽  
Vol 150 (4) ◽  
pp. 756-764 ◽  
Author(s):  
LING-LING XIAO ◽  
GUO-DONG WANG ◽  
HAO WANG ◽  
ZONG-SHENG JIANG ◽  
CHUN-RONG DIWU ◽  
...  
Keyword(s):  
High Resolution ◽  
North China Craton ◽  
North China ◽  
Metamorphic Complex ◽  
Middle Section ◽  
The South ◽  
The North ◽  
Facies Metamorphism ◽  
Isothermal Decompression ◽  
Metamorphic Terranes

AbstractAmphibolites and metapelites exposed in the Zanhuang metamorphic complex situated in the south-middle section of the Trans-North China Orogen (TNCO) underwent upper-amphibolite-facies metamorphism and record clockwise P–T paths including retrograde isothermal decompression. High-resolution zircon U–Pb geochronological analyses indicate that the metamorphic peak occurred during ~ 1840–1860 Ma, which is in accordance with the ubiquitous metamorphic ages of ~ 1850 Ma retrieved by miscellaneous geochronologic methods throughout the metamorphic terranes of the northern TNCO, confirming that the south-middle section of the TNCO was involved in the amalgamation of the Eastern and Western Blocks of the North China Craton during the Palaeoproterozoic.

scholarly journals RAS-NAAD: 40-yr High-Resolution North Atlantic Atmospheric Hindcast for Multipurpose Applications (New Dataset for the Regional Mesoscale Studies in the Atmosphere and the Ocean)

2020 ◽  
Vol 59 (5) ◽  
pp. 793-817 ◽  
Author(s):  
Alexander Gavrikov ◽  
Sergey K. Gulev ◽  
Margarita Markina ◽  
Natalia Tilinina ◽  
Polina Verezemskaya ◽  
...  
Keyword(s):  
High Resolution ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Lateral Boundary Condition ◽  
Three Dimensional Model ◽  
Free Atmosphere ◽  
The North ◽  
The North Atlantic

AbstractWe present in this paper the results of the Russian Academy of Sciences North Atlantic Atmospheric Downscaling (RAS-NAAD) project, which provides a 40-yr 3D hindcast of the North Atlantic (10°–80°N) atmosphere at 14-km spatial resolution with 50 levels in the vertical direction (up to 50 hPa), performed with a regional setting of the WRF-ARW 3.8.1 model for the period 1979–2018 and forced by ERA-Interim as a lateral boundary condition. The dataset provides a variety of surface and free-atmosphere parameters at sigma model levels and meets many demands of meteorologists, climate scientists, and oceanographers working in both research and operational domains. Three-dimensional model output at 3-hourly time resolution is freely available to the users. Our evaluation demonstrates a realistic representation of most characteristics in both datasets and also identifies biases mostly in the ice-covered regions. High-resolution and nonhydrostatic model settings in NAAD resolve mesoscale dynamics first of all in the subpolar latitudes. NAAD also provides a new view of the North Atlantic extratropical cyclone activity with a much larger number of cyclones as compared with most reanalyses. It also effectively captures highly localized mechanisms of atmospheric moisture transports. Applications of NAAD to ocean circulation and wave modeling are demonstrated.

scholarly journals Short communication: A semi-automated method for rapid fault slip analysis from topographic scarp profiles

2019 ◽  
Author(s):  
Franklin D. Wolfe ◽  
Timothy A. Stahl ◽  
Pilar Villamor ◽  
Biljana Lukovic
Keyword(s):  
Monte Carlo ◽  
High Resolution ◽  
Open Source ◽  
Hanging Wall ◽  
Temporal Analysis ◽  
Fault Scarp ◽  
Fault Slip ◽  
Source Characterization ◽  
Automated Method ◽  
Wide Range

Abstract. Here, we introduce an open source, semi-automated, Python-based graphical user interface (GUI) called the Monte Carlo Slip Statistics Toolkit (MCSST) for estimating dip slip on individual or bulk fault datasets. Using this toolkit, profiles are defined across fault scarps in high-resolution digital elevation models (DEMs) and then relevant fault scarp components are interactively identified (e.g., footwall, hanging wall, and scarp). Displacement statistics are calculated automatically using Monte Carlo simulation and can be conveniently visualized in Geographic Information Systems (GIS) for spatial analysis. Fault slip rates can also be calculated when ages of footwall and hanging wall surfaces are known, allowing for temporal analysis. This method allows for rapid analysis of tens to hundreds of faults in rapid succession within GIS and a Python coding environment. Application of this method may contribute to a wide range of regional and local earthquake geology studies with adequate high-resolution DEM coverage, both regional fault source characterization for seismic hazard and/or estimating geologic slip and strain rates, including creating long-term deformation maps. ArcGIS versions of these functions are available, as well ones that utilize free, open source Quantum GIS (QGIS) and Jupyter Notebook Python software.

Outcrops and well logs as a practicum for calibrating the accuracy of traveltime tomograms

2015 ◽  
Vol 3 (3) ◽  
pp. SY27-SY40 ◽  
Author(s):  
Sherif M. Hanafy ◽  
Ann Mattson ◽  
Ronald L. Bruhn ◽  
Shengdong Liu ◽  
Gerard T. Schuster
Keyword(s):  
High Resolution ◽  
Fault Zone ◽  
Great Basin ◽  
Seismic Tomography ◽  
Seismic Data ◽  
Hanging Wall ◽  
Normal Fault ◽  
Well Logs ◽  
Drill Core ◽  
Sufficient Detail

We have developed two case studies demonstrating the use of high-resolution seismic tomography and reflection imaging in the field of paleoseismology. The first study, of the Washington fault in southern Utah, USA, evaluated the subsurface deposits in the hanging wall of the normal fault. The second study, of the Mercur fault in the eastern Great Basin of Utah, USA, helped to establish borehole locations for sampling subsurface colluvial deposits buried deeper than those previously trenched along the fault zone. We evaluated the seismic data interpretations by comparison with data obtained by trenching and logging deposits across the Washington fault, and by drill-core sampling and video logging of boreholes penetrating imaged deposits along the Mercur fault. The seismic tomograms provided critical information on colluvial wedges and faults but lacked sufficient detail to resolve individual paleoearthquakes.

The significance of switch in convergence direction in the Alborz Mountains, northern Iran: Insights from scaled analogue modeling

2017 ◽  
Vol 5 (1) ◽  
pp. SD81-SD98 ◽  
Author(s):  
Majid Shahpasandzadeh ◽  
Hemin Koyi ◽  
Faramarz Nilfouroushan
Keyword(s):  
Active Tectonics ◽  
Deformation Pattern ◽  
Eurasian Plate ◽  
The South ◽  
South Caspian Basin ◽  
Northern Iran ◽  
The North ◽  
Structural Style ◽  
Analogue Models ◽  
North Of Iran

The switch in direction of convergence between Central Iran and the Eurasian Plate is believed to have a significant impact on the structural style in the Alborz Mountains, in the north of Iran. To understand the deformation pattern and investigate the influence of the South Caspian Basin kinematics since the middle Miocene on the structural styles and active tectonics of the Alborz Mountains, a series of scaled analogue models were prepared, in which passively layered loose sand simulating the sedimentary units were subjected to orthogonal and subsequently oblique shortening by a rigid indenter. Model results indicate that during the shortening, an arcuate-shaped foreland-vergent imbricate stack forms in front of the indenter. The orthogonal shortening is characterized by a prevailing right-lateral and left-lateral oblique-slip motion in the east and west of the model, respectively. This shift in kinematics contradicts the proposed preneotectonic (orthogonal) model of the Alborz. However, during oblique shortening, model results show that deformation is mainly accommodated by left-lateral transpression within the sand wedge and internal deformation. Oblique shortening is consistently accommodated by continued left-lateral motion on the west-northwest-trending oblique thrusts, whereas the east–west-trending thrusts and the preexisting east-northeast-trending right-lateral oblique thrusts reactivate as left-lateral oblique faults. Precise monitoring of the model surface also illustrates partitioning of shortening into the foreland-vergent left-lateral thrusting in the south and hinterland-vergent back thrusting in the north. These model results are generally consistent with field observations and GPS data of structure and kinematics of the Alborz Mountains.

scholarly journals Sevier Fault at Red Canyon

Geosites ◽  
2019 ◽  
Vol 1 ◽  
pp. 1-6
Author(s):  
Robert Biek
Keyword(s):  
Lava Flow ◽  
Fault Zone ◽  
Hanging Wall ◽  
Slip Rate ◽  
Normal Fault ◽  
Coarse Grained ◽  
Seismic Reflection Data ◽  
The North ◽  
Total Displacement ◽  
Reflection Data

The Sevier fault is spectacularly displayed on the north side of Utah Highway 12 at the entrance to Red Canyon, where it offsets a 500,000-year-old basaltic lava flow. The fault is one of several active, major faults that break apart the western margin of the Colorado Plateau in southwestern Utah. The Sevier fault is a “normal” fault, a type of fault that forms during extension of the earth’s crust, where one side of the fault moves down relative to the other side. In this case, the down-dropped side (the hanging wall) is west of the fault; the upthrown side (the footwall) lies to the east. The contrasting colors of rocks across the fault make the fault stand out in vivid detail. Immediately south of Red Canyon, the 5-million-year-old Rock Canyon lava flow, which erupted on the eastern slope of the Markagunt Plateau, flowed eastward and crossed the fault (which at the time juxtaposed non-resistant fan alluvium against coarse-grained volcaniclastic deposits) (Biek and others, 2015). The flow is now offset 775 to 1130 feet (235-345 m) along the main strand of the fault, yielding an anomalously low vertical slip rate of about 0.05 mm/yr (Lund and others, 2008). However, this eastern branch of the Sevier fault accounts for only part of the total displacement on the fault zone. A concealed, down-to-the-west fault is present west of coarse-grained volcaniclastic strata at the base of the Claron cliffs. Seismic reflection data indicate that the total displacement on the fault zone in this area is about 3000 feet (900 m) (Lundin, 1987, 1989; Davis, 1999).

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