scholarly journals Palaeogeological hiatus surface mapping: a tool to visualize vertical motion of the continents

2018 ◽  
Vol 156 (2) ◽  
pp. 308-319 ◽  
Author(s):  
ANKE M. FRIEDRICH
Keyword(s):  
Reference Frames ◽  
Vertical Motion ◽  
Vertical Surface ◽  
Single Step ◽  
Geological Mapping ◽  
Physical Models ◽  
Resolving Power ◽  
Dynamic Topography ◽  
Surface Mapping ◽  
Surface Motion

AbstractDynamic topography is a well-established consequence of global geodynamic models of mantle convection with horizontal dimensions of >1000 km and amplitudes up to 2 km. Such physical models guide the interpretation of geological records on equal dimensions. Continent-scale geological maps therefore serve as reference frames of choice to visualize erosion/non-deposition as a proxy for long-wavelength, low-amplitude vertical surface motion. At a resolution of systems or series, such maps display conformable and unconformable time boundaries traceable over hundreds to thousands of kilometres. Unconformable contact surfaces define the shape and size of time gap (hiatus) in millions of years based on the duration of time represented by the missing systems or series. Hiatus for a single system or series base datum diminishes laterally to locations (anchor points) where it is conformable at the mapped resolution; it is highly dependent upon scale. A comparison of hiatus area between two successive system or series boundaries yields changes in location, shape, size and duration, indicative of the transient nature of vertical surface motion. As a single-step technique, it serves as a quantitative proxy for palaeotopography that can be calibrated using other geological data. The tool magnifies the need for geological mapping at the temporal resolution of stages, matching process rates. The method has no resolving power within conformable regions (basins) but connects around them. When applied to marine seismic sections that relate to rock record, not to time, biostratigraphic and radiometric data from deep wells are needed before hiatus areas – that relate to time – can be mapped.

scholarly journals Southern California’s Crustal Motion Tells of Earthquake Hazards

Eos ◽  
2020 ◽  
Vol 101 ◽  
Author(s):  
Aaron Sidder
Keyword(s):  
Vertical Surface ◽  
Earthquake Hazards ◽  
Surface Motion ◽  
Crustal Motion

Precise measurements of the Earth’s vertical surface motion help to elucidate the hazards of faults in an earthquake-prone region.

scholarly journals Determining the Plio-Quaternary uplift of the southern French massif-Central; a new insights for intraplate orogen dynamics

2019 ◽  
Author(s):  
Oswald Malcles ◽  
Philippe Vernant ◽  
Jean Chéry ◽  
Pierre Camps ◽  
Gaël Cazes ◽  
...  
Keyword(s):  
Numerical Models ◽  
Morphological Evolution ◽  
Vertical Motion ◽  
French Massif Central ◽  
Dynamic Topography ◽  
Active Deformation ◽  
Massif Central ◽  
The North ◽  
Cave System ◽  
Clay Deposits

Abstract. The evolution of intra-plate orogens is still poorly understood. Yet, this is of major importance for understanding the Earth and plate dynamic, as well as the link between surface and deep geodynamic processes. The French Massif Central is an intraplate orogen with a mean elevation of 1000 m, with the highest peak elevations ranging from 1500 m to 1885 m. However, active deformation of the region is still debated due to scarce evidence either from geomorphological or geophysical (i.e. geodesy and seismology) data. Because the Cévennes margin allows the use of karst sediments geochronology and morphometrical analysis, we study the vertical displacements of that region: the southern part of the French Massif-Central. Geochronology and morphometrical results, helped with lithospheric-scale numerical modelling, allow, then, a better understanding of this intraplate-orogen evolution and dynamic. Using the ability of the karst to durably record morphological evolution, we first quantify the incision rates. We then investigate tilting of geomorphological benchmarks by means of a high-resolution DEM. We finally use the newly quantified incision rates to constrain numerical models and compare the results with the geomorphometric study. We show that absolute burial age (10Be/26Al on quartz cobbles) and the paleomagnetic analysis of karstic clay deposits for multiple cave system over a large elevation range correlate consistently. This correlation indicates a regional incision rate of 83.4 +17.3/−5.4 m Ma−1 during the last ca 4 Myrs (Plio-Quaternary). Moreover, we point out through the analysis of 55 morphological benchmarks that the studied region has undergone a regional southward tilting. This tilting is expected as being due to a differential vertical motion between the north and southern part of the studied area. Numerical models show that erosion-induced isostatic rebound can explain up to two-thirds of the regional uplift deduced from dating technics and are consistent with the southward tilting obtain from morphological analysis. We presume that the remaining part is related to dynamic topography or thermal isostasy due to the Massif Central plio-quaternary magmatism.

Steep channel freezeup processes: understanding complexity with statistical and physical models

2015 ◽  
Vol 42 (9) ◽  
pp. 622-633 ◽  
Author(s):  
Mathieu Dubé ◽  
Benoit Turcotte ◽  
Brian Morse
Keyword(s):  
Degrees Of Freedom ◽  
Heat Budget ◽  
Morphological Characteristics ◽  
Large Data ◽  
Quantitative Information ◽  
Single Step ◽  
Physical Models ◽  
Data Set ◽  
Multiple Parameters ◽  
Physically Based

The development of ice dams in steep channels dictates water level variations and influences flow rates and habitat conditions. Despite the dominance of ice dam development in cold region gravel bed channels, practicing engineers and scientists have access to very little quantitative information describing this complex freezeup process. This paper aims to fill this gap by presenting a large data set on the process. The substantial variations observed in formation and melting rates from one site to the next and from one year to the next at the same site are explained with a physically-based numerical model that includes a complete heat budget applied to single step-pool sequence. The model successfully simulates the entire development of an ice dam and shows that the process depends on multiple parameters, or degrees of freedom. It also reveals that morphological characteristics greatly influence ice dam dynamics.

scholarly journals Subregion-Scale Hindcasting of Contrail Outbreaks, Utilizing Their Synoptic Climatology

2015 ◽  
Vol 54 (8) ◽  
pp. 1733-1755
Author(s):  
Andrew M. Carleton ◽  
Armand D. Silva ◽  
Jase Bernhardt ◽  
Justin VanderBerg ◽  
David J. Travis
Keyword(s):  
Vertical Wind Shear ◽  
Vertical Motion ◽  
Binary Logistic Regression ◽  
Physical Models ◽  
Synoptic Climatology ◽  
Statistical Prediction ◽  
Clear Sky ◽  
Sensitivity Tests ◽  
Explicit Consideration ◽  
Further Development

AbstractContrail statistical prediction methods are often location specific. To take advantage of the fact that the upper-tropospheric (UT) meteorological conditions that favor “clear-sky outbreaks” of persisting contrails, or contrail favored areas (CFAs), tend to be synoptic in scale, a visual UT-map technique to hindcast CFAs has been developed and tested for subregions of the contiguous United States (CONUS) that have high outbreak frequencies in midseason months (January, April, July, and October) of 2000–02. The method compares daily maps with the composite fields for outbreak days (CON) versus nonoutbreak days (NON), and those assessments are evaluated using standard skill measures. Binary logistic regression determines which UT variables are significant predictors, individually and in combination. The reproducibility of the outbreak hindcast results is tested on the same subregions for the corresponding months of 2008–09. The results confirm the importance of UT relative humidity and vertical-motion (omega) map patterns in regional clear-sky outbreaks. Although the hindcast skill is modest, sensitivity tests suggest that the method will be substantially improved when a longer-term climatological dataset of outbreaks becomes available (to increase sample sizes) and with explicit consideration of the synoptic types on CON days. The latter is demonstrated specifically for the southern CONUS in January, where to improve hindcast success one should also consider the vertical wind shear in the upper troposphere, given the importance of the subtropical jet stream in contrail outbreaks there. Further development of the method to improve its skill ultimately should permit its use in combination with existing objective (statistical and physical models) methods of contrail prediction.

scholarly journals Application of Measurement While Drilling Technology to Predict Rock Mass Quality and Rock Support for Tunnelling

2019 ◽  
Vol 53 (3) ◽  
pp. 1349-1358 ◽  
Author(s):  
Jeroen van Eldert ◽  
Håkan Schunnesson ◽  
Daniel Johansson ◽  
David Saiang
Keyword(s):  
Rock Mass ◽  
Site Investigation ◽  
Geological Mapping ◽  
Limited Information ◽  
Rock Support ◽  
Surface Mapping ◽  
Rock Mass Quality ◽  
Drilling Technology ◽  
Tunnel Design ◽  
Measurement While Drilling

Abstract A tunnelling project is normally initiated with a site investigation to determine the in situ rock mass conditions and to generate the basis for the tunnel design and rock support. However, since site investigations often are based on limited information (surface mapping, geophysical profiles, few bore holes, etc.), the estimation of the rock mass conditions may contain inaccuracies, resulting in underestimating the required rock support. The study hypothesised that these inaccuracies could be reduced using Measurement While Drilling (MWD) technology to assist in the decision-making process. A case study of two tunnels in the Stockholm bypass found the rock mass quality was severely overestimated by the site investigation; more than 45% of the investigated sections had a lower rock mass quality than expected. MWD data were recorded in 25 m grout holes and 6 m blast holes. The MWD data were normalised so that the long grout holes with larger hole diameters and the shorter blast holes with smaller hole diameters gave similar results. With normalised MWD data, it was possible to mimic the tunnel contour mapping; results showed good correlation with mapped Q-value and installed rock support. MWD technology can improve the accuracy of forecasting the rock mass ahead of the face. It can bridge the information gap between the early, somewhat uncertain geotechnical site investigation and the geological mapping done after excavation to optimise rock support.

scholarly journals Composite Vertical-Motion Patterns near North American Polar–Subtropical Jet Superposition Events

2020 ◽  
Vol 148 (11) ◽  
pp. 4565-4585
Author(s):  
Andrew C. Winters ◽  
Daniel Keyser ◽  
Lance F. Bosart
Keyword(s):  
Large Scale ◽  
Vertical Motion ◽  
Geostrophic Wind ◽  
Single Step ◽  
Subsequent Formation ◽  
Motion Patterns ◽  
Wind Speeds ◽  
Middle Latitudes ◽  
Subtropical Jet ◽  
Large Scale Flow

AbstractA polar–subtropical jet superposition is preceded by the development of a polar cyclonic potential vorticity (PV) anomaly at high latitudes and a tropical anticyclonic PV anomaly at subtropical latitudes. A confluent large-scale flow pattern can lead to the juxtaposition of these respective PV anomalies at middle latitudes, resulting in the addition of the nondivergent circulations induced by each PV anomaly and an increase in upper-tropospheric wind speeds at the location of jet superposition. Once these PV anomalies become juxtaposed, vertical motion within the near-jet environment facilitates the advection and diabatic redistribution of tropopause-level PV, and the subsequent formation of the steep, single-step tropopause structure that characterizes a jet superposition. Given the importance of vertical motion during the formation of jet superpositions, this study adopts a quasigeostrophic (QG) diagnostic approach to quantify the production of vertical motion during three types of jet superposition events: polar dominant, eastern subtropical dominant, and western subtropical dominant. The diagnosis reveals that the geostrophic wind induced by polar cyclonic QGPV anomalies is predominantly responsible for QG vertical motion in the vicinity of jet superpositions. The QG vertical motion diagnosed from the along-isotherm component of the Q vector, which represents the vertical motion associated with synoptic-scale waves, is dominant within the near-jet environment. The QG vertical motion diagnosed from the across-isotherm component of the Q vector, which represents the vertical motion associated with frontal circulations in the vicinity of the jet, is subordinate within the near-jet environment, but is relatively more important during eastern subtropical dominant events compared to polar dominant and western subtropical dominant events.

3D surface velocity variations of the Argentière glacier (French Alps) monitored with a high resolution continuous GNSS network

2020 ◽  
Author(s):  
Andrea Walpersdorf ◽  
Christian Vincent ◽  
Florent Gimbert ◽  
Agnès Helmstetter ◽  
Luc Moreau ◽  
...  
Keyword(s):  
High Resolution ◽  
Water Pressure ◽  
Cavity Growth ◽  
Vertical Surface ◽  
Physical Models ◽  
Surface Velocity ◽  
Reference Station ◽  
Data Set ◽  
Daily Cycles ◽  
Basal Sliding

<p>Five continuous GNSS stations monitor the Argentière glacier surface motion on a longitudinal profile at 2400 m altitude over a full melt season, from April to November 2019. High precision data analysis is enabled by a close-by reference station on the bedrock. This GNSS survey is part of the SAUSSURE project 2019-2022 that aims at increasing our knowledge on the physics of glacier basal sliding, by improving friction laws and validating them in a natural environment. The Argentière glacier is particularly interesting due to its long-term subglacial observatory measuring basal sliding velocity and subglacial discharge. The SAUSSURE project furthermore includes seismic, tiltmeter and piezometer measurements. The bedrock topography is obtained from a Ground Penetrating Radar.</p><p>The dense GNSS station setup permits to validate individual antenna movements. We then retrieve horizontal and vertical surface velocities on daily and sub-daily time scales. We can deduce strain rates in between the stations and their evolution in time, and relate this observable with the vertical surface motions. The confrontation of the GNSS data with independent observations allows analyzing the surface motions searching for glacier surges that combine horizontal speed-ups combined with uplift due to bed separation of the ice sheet. These events could give indications about cavity growth in spring. We will also try to investigate sub-daily motions that seem to occur in daily cycles in summer, as hinted at by the basal sliding measurements. These daily cycles are usually also seen in the seismic activity. The phase of the different features varies with respect to the daily cycles of temperature and sub-glacial water pressure. These phase offsets can give us indices on eventual mechanisms of sliding at the bedrock interface. The GNSS measurements represent a rare in situ data set that can contribute to better apprehend mechanisms of basal sliding and to provide high-resolution 3D constraints on physical models of glacier flow.</p>

Automated Microinjection System Design and Experiments Based on Hybrid-Driven Micro-Robot

2014 ◽  
Vol 1049-1050 ◽  
pp. 1116-1121
Author(s):  
Chuan Bo Qin ◽  
Lian Fang Tian ◽  
Qi Liang Du ◽  
Qin Zhang
Keyword(s):  
System Design ◽  
Degrees Of Freedom ◽  
Low Cost ◽  
Vertical Direction ◽  
Vertical Motion ◽  
Single Step ◽  
Experimental Result ◽  
Micro Robot ◽  
Maximum Range ◽  
Motion Performance

In order to resolve the operation difficulty, high cost problems of traditional manual cell microinjection, a low-cost microinjection system based on hybrid-driven micro-robot is presented. System is mainly composed of microscope, 3-DOF(degrees of freedom) micro-robot, signal generator and power amplifier. Firstly, we describe the automated microinjection system. Secondly, we analyze the motion performance of the robot in the horizontal and vertical direction. The single step resolution is less than 5um each step working at a frequency more than 200Hz. Maximum range of vertical motion is 5mm and minimum resolution ups to 2um. Finally, shrimp egg microinjection experiment is conducted using our system. The experimental result shows that this proposed scheme is simple, reproducible and can achieve microinjection success rate of 88%.

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