scholarly journals Application of observations of recent tectonic activity in the Świebodzice Depression (the Sudetes, SW Poland) in assessing seismic hazard in the Fore-Sudetic Monocline

2018 ◽  
Vol 55 ◽  
pp. 00001 ◽  
Author(s):  
Marek Kaczorowski ◽  
Damian Kasza ◽  
Ryszard Zdunek ◽  
Roman Wronowski
Keyword(s):  
Vertical Movement ◽  
Rock Massif ◽  
Fault System ◽  
Tectonic Activity ◽  
Regional Tectonic ◽  
Sw Poland ◽  
Tidal Signal ◽  
Representative Function ◽  
Low Activity

Tiltmeter observations with application of horizontal pendulums have been carried out for 40 years in the Geodynamic Laboratory in Książ. Long-term observations have not indicated any correlation of these data with meteorological or seasonal phenomena. Following an epoch of fast azimuth changes, a gradual compensation process took place, excluding the effect of gravitational creep of the rock massif. An assumption was made that the observed large changes of the equilibrium azimuths of the horizontal pendulums that result from tectonic tilt of the foundation blocks. Multiannual tiltmeter observations allowed to determine the temporal characteristics and amplitude tectonic effects. Intervals of strong tectonic activity in the rock massif of the Świebodzice Depression last from several days to over ten weeks and are separated by several tens of hours of low activity. Amplitude of the rock massif deformation reaches values from over ten to several tens of amplitudes of the tidal signal, i.e. up to several hundreds of micrometres. Water-tube tiltmeters (WT) launched in 2003 have confirmed the characteristics of tectonic effects and their incidental occurrence. Beside the tilt effects, WT have enabled to confirm vertical movement of the foundation blocks. Geological investigations in the Świebodzice Depression have indicated the presence of a numerous faults separating particular blocks in the rock massif. The presence of this fault system favours the dislocation of foundation blocks, which results in a quake-less relaxation of tectonic stresses and absence lack of seismic activity in the Świebodzice Depression. Foundation blocks separated by faults combined with the multiscale measurement system of WTs form a natural detector of regional tectonic activity, allowing to determine with micrometric resolution the representative function of tectonic activity in the rock massif of the Świebodzice Depression.

scholarly journals Time Dependencies Between Tectonic Activity of Świebodzice Depression (SW Poland) and Seismic Activity in Poland and Czech Mining Regions

2019 ◽  
Vol 105 ◽  
pp. 02001
Author(s):  
Marek Kaczorowski ◽  
Damian Kasza ◽  
Ryszard Zdunek ◽  
Marcin Rudnicki ◽  
Roman Wronowski
Keyword(s):  
Seismic Activity ◽  
Rock Massif ◽  
Tectonic Activity ◽  
Tectonic Events ◽  
Time Dependencies ◽  
Sw Poland ◽  
Surrounding Areas ◽  
Low Activity ◽  
Mining Regions ◽  
Amplitude Characteristics

Since the 1970-ties, large azimuth changes in the equilibrium of quartz horizontal pendulums have been irregularly registered in the Geodynamic Laboratory in Książ. However, azimuth changes of the pendulums did not correlate with meteorological phenomena and the compensation phases of these changes excluded processes of gravitational creep of the rock massif. It was assumed that changes of these azimuths result from tectonic tilt of the rock massif. These were the first observations of contemporary tectonic activity in the Świebodzice Depression (SW Poland). Multiannual observations have allowed for determining temporal and amplitude characteristics of such tectonic activity. Intervals of tectonic activity last from several days to two weeks and are separated by periods of low activity or even no activity. During tectonic events, amplitudes of rock massif deformation reach values of several tens of tidal amplitudes. The distinguished characteristics of tectonic effects and their incidental character have been confirmed by water-tube tiltmeters (WT) activated in the Geodynamic Laboratory in the early 2000s. Unique conditions of the rock massif cause that the WTs, in connection with blocks of the rock massif separated by faults, are natural detectors of tectonic activity, allowing to determine the function of tectonic activity and its derivatives in the surrounding areas.

scholarly journals Long-term shoreline shifts on continental blocks during the Bajocian: an updated interpretation based on synthetic stratigraphical and palaeogeographical developments on regional scales

Geologos ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Dmitry A. Ruban ◽  
Emad S. Sallam
Keyword(s):  
Sea Level ◽  
Western Siberia ◽  
Control Mechanism ◽  
Russian Platform ◽  
Tectonic Activity ◽  
Sea Level Changes ◽  
Regional Tectonic ◽  
Global Sea Level ◽  
Apparent Stability

Abstract Available reconstructions of Jurassic global sea level changes differ and are in need of an update. New stratigraphical charts and palaeogeographical developments for a number of large continental blocks or their portions of these (e.g., Germany, India, northeast Africa, northwest Australia, the Russian Platform and western Siberia) reveal regional long-term shoreline shifts (i.e., transgressions and regressions) during the Bajocian Stage (168.3–170.3 Ma). A comparison of these allows to document only a single coherent feature, namely the earliest Bajocian transgression, in the majority of the continental blocks considered. Undoubtedly, this event was triggered by a eustatic rise. However, long-term shoreline shifts were either weak to absent or differed between the blocks during almost the entire Bajocian, thus providing evidence of the apparent stability of global sea level and the importance of regional tectonic activity as a control mechanism on particular transgressions and regressions. Interestingly, it appears that the earliest Bajocian eustatic rise was a constituent of a long-term eustatic pattern; the nature of this event has yet to be fully understood. Generally, the findings presented here are in better agreement with Anthony Hallam’s view of Jurassic eustasy and question some other global sea level reconstructions.

scholarly journals Tectonic Structure and Relationship with Sinkhole Harzard in Bang Lung Area, Cho Don District, Bac Kan Province

2021 ◽  
Vol 37 (2) ◽  
Author(s):  
Bui Van Thom ◽  
Tran Quoc Cuong ◽  
Lai Hop phong ◽  
Tran Trung Hieu ◽  
Nguyen Duc Anh
Keyword(s):  
Human Impacts ◽  
Vertical Movement ◽  
Fault System ◽  
Tectonic Activity ◽  
Fracture Zones ◽  
Karst Caves ◽  
Groundwater Fluctuation ◽  
Lung Area ◽  
Unconsolidated Sediment ◽  
Sediment Layers

By integration of remote sensing images analysis, geology, geomorphology, hydrogeology, geophysical method, and drilling data, the paper illustrates the structure tectonics, causes, and initial mechanism of a sinkhole forming in Bang Lung, Cho Don, Bac Kan province. The NE-SW normal slip faults are an essential fault system in the area, which created Bang Lung graben valley. This fault system also forms large fracture zones, creating advantage conditions for the groundwater runoff both vertically and horizontally to eroded and dissolved carbonate rock-forming underground karst caves. These are favorable natural conditions for forming a sinkhole. The sinkhole hazard in the Bang Lung area is initiated by some main factors such as tectonic activity, thickness, and characteristics of unconsolidated sediment layers, groundwater fluctuation, karst caves, and human activities. The most human impacts are mining exploitation and agricultural cultivation that promote sinkholes occurring faster and earlier. The horizontal and vertical movement of groundwater dragged the material on the ceiling karst caves into ground spaces. Thereby, weakening the cohesion of the unconsolidated sediment above caves leads to gravitational unbalance and creates a sinkhole. This study has also shown potential sinkhole areas in Bang Lung, which helps the authorities and local people in sinkhole prevention and mitigation mission.  

Erosion rates of the New Zealand Southern Alps reflect long-term tectonics and transient climate

2021 ◽  
Author(s):  
Duna Roda-Boluda ◽  
Taylor Schildgen ◽  
Hella Wittmann-Oelze ◽  
Stefanie Tofelde ◽  
Aaron Bufe ◽  
...  
Keyword(s):  
New Zealand ◽  
Strike Slip ◽  
Southern Alps ◽  
Fault System ◽  
Tectonic Deformation ◽  
Seismic Cycle ◽  
Erosion Rates ◽  
Alpine Fault ◽  
Oblique Convergence

<p>The Southern Alps of New Zealand are the expression of the oblique convergence between the Pacific and Australian plates, which move at a relative velocity of nearly 40 mm/yr. This convergence is accommodated by the range-bounding Alpine Fault, with a strike-slip component of ~30-40 mm/yr, and a shortening component normal to the fault of ~8-10 mm/yr. While strike-slip rates seem to be fairly constant along the Alpine Fault, throw rates appear to vary considerably, and whether the locus of maximum exhumation is located near the fault, at the main drainage divide, or part-way between, is still debated. These uncertainties stem from very limited data characterizing vertical deformation rates along and across the Southern Alps. Thermochronology has constrained the Southern Alps exhumation history since the Miocene, but Quaternary exhumation is hard to resolve precisely due to the very high exhumation rates. Likewise, GPS surveys estimate a vertical uplift of ~5 mm/yr, but integrate only over ~10 yr timescales and are restricted to one transect across the range.</p><p>To obtain insights into the Quaternary distribution and rates of exhumation of the western Southern Alps, we use new <sup>10</sup>Be catchment-averaged erosion rates from 20 catchments along the western side of the range. Catchment-averaged erosion rates span an order of magnitude, between ~0.8 and >10 mm/yr, but we find that erosion rates of >10 mm/yr, a value often quoted in the literature as representative for the entire range, are very localized. Moreover, erosion rates decrease sharply north of the intersection with the Marlborough Fault System, suggesting substantial slip partitioning. These <sup>10</sup>Be catchment-averaged erosion rates integrate, on average, over the last ~300 yrs. Considering that the last earthquake on the Alpine Fault was in 1717, these rates are representative of inter-seismic erosion. Lake sedimentation rates and coseismic landslide modelling suggest that long-term (~10<sup>3</sup> yrs) erosion rates over a full seismic cycle could be ~40% greater than our inter-seismic erosion rates. If we assume steady state topography, such a scaling of our <sup>10</sup>Be erosion rate estimates can be used to estimate rock uplift rates in the Southern Alps. Finally, we find that erosion, and hence potentially exhumation, does not seem to be localized at a particular distance from the fault, as some tectonic and provenance studies have suggested. Instead, we find that superimposed on the primary tectonic control, there is an elevation/temperature control on erosion rates, which is probably transient and related to frost-cracking and glacial retreat.</p><p>Our results highlight the potential for <sup>10</sup>Be catchment-averaged erosion rates to provide insights into the magnitude and distribution of tectonic deformation rates, and the limitations that arise from transient erosion controls related to the seismic cycle and climate-modulated surface processes.</p><p> </p><p> </p>

Salt thickness and heterogeneity control the degree of coupling between sub- and supra-salt structure during salt-detached translation: evidence from physical models

2021 ◽  
Author(s):  
Sian Evans ◽  
Christopher Jackson ◽  
Sylvie Schueller ◽  
Jean-Marie Mengus
Keyword(s):  
Structural Evolution ◽  
Structural Complexity ◽  
Vertical Movement ◽  
Sediment Supply ◽  
Physical Models ◽  
Structural Development ◽  
Salt Structure ◽  
Regional Tectonic ◽  
Base Salt ◽  
Strain Coupling

<p>Salt flows like a fluid over geological timescales and introduces significant structural complexity to the basins in which it is deposited. Salt typically flows seaward due to tilting of the basin margins, and is therefore influenced by the geometry of the surface that it flows across (e.g. fault scarps or folds on the base-salt surface). This can lead to coupling of sub- and supra-salt structures, with the orientation and distribution of base-salt structures reflected in the structure of the overburden. However, precisely what controls the degree of strain coupling during salt-detached translation is still poorly understood, in particular the role played by salt thickness and lithological heterogeneity. This partly reflects the fact that it can be difficult to deconvolve the relative contributions of natural variables such as the magnitude of relief, sediment supply, and regional tectonic regime. In addition, seismic data provide only the present structural configuration of salt basins, from which their formative kinematics must be inferred. If we can develop a better understanding of how sub-salt structure controls the types and patterns of supra-salt deformation, we can produce better kinematic (structural) restorations of salt basins and, therefore, have a better understanding of the related mechanics.</p><p>In order to isolate the influence of salt thickness and heterogeneity on sub- to supra-salt strain coupling during salt-detached horizontal translation, we present a series of physical analogue models with controlled boundary conditions. We use a simple base-salt geometry comprising three oblique base-salt steps, and vary the thickness and composition of the ductile salt analogue in each experiment. X-ray tomography allows us to image the internal structure during model evolution and therefore gain a 4D picture of its structural development.</p><p>Results show that thicker and more homogeneous salt units experience more vertical movement (i.e. minibasin subsidence and diapiric rise) and the overburden structure is less explicitly coupled with the underlying base-salt relief. Conversely, thinner and more heterogeneous salt units restrict vertical movement, and therefore the resulting overburden structure is dominated by lateral movement and more closely coupled to the geometry of the base-salt surface. These results highlight the important role of base-salt relief in the subsequent structural evolution of salt basins and why, despite broad similarities between different salt basins, there is significant variability in their structural styles.</p>

The Fairbanks earthquakes of June 21, 1967; aftershock distribution, focal mechanisms, and crustal parameters

1969 ◽  
Vol 59 (1) ◽  
pp. 73-100
Author(s):  
Larry Gedney ◽  
Eduard Berg
Keyword(s):  
P Wave ◽  
Fault System ◽  
Crustal Layer ◽  
Near Surface ◽  
Fault Surface ◽  
True Value ◽  
Regional Tectonic ◽  
Tectonic System ◽  
Relationship Of ◽  
The Relationship

Abstract A series of moderately severe earthquakes occurred in the vicinity of Fairbanks, Alaska, on the morning of June 21, 1967. During the following months, many thousands of aftershocks were recorded in order to outline the aftershock zone and to resolve the focal mechanism and its relation to the regional tectonic system. No fault is visible at the surface in this area. Foci were found to occupy a relatively small volume in the shape of an ablate cylinder tilted about 30° from the vertical. The center of the zone lay about 12 kilometers southeast of Fairbanks. Focal depths ranged from near-surface to 25 kilometers, although most were in the range 9-16 km. In the course of the investigation, it was found that the Jeffreys and Bullen velocity of 5.56 km/sec for the P wave in the upper crustal layer is very near the true value for this arec, and that the use of 1.69 for the Vp/Vs ratio gives good results in most cases. The proposed faulting mechanism involves nearly equal components of right-lateral strike slip, and normal faulting with northeast side downthrown on a system of sub-parallel faults striking N40°W. The fault surface appears to be curved—dipping from near vertical close to the surface to less steep northeast dips at greater depths. The relationship of this fault system with the grosser aspects of regional tectonism is not clear.

scholarly journals Autogenic versus allogenic controls on the evolution of a coupled fluvial megafan/mountainous catchment system: numerical modelling and comparison with the Lannemezan megafan system (Northern Pyrenees, France)

2016 ◽  
Author(s):  
Margaux Mouchené ◽  
Peter van der Beek ◽  
Sébastien Carretier ◽  
Frédéric Mouthereau
Keyword(s):  
Numerical Modelling ◽  
Temporal Variations ◽  
Tectonic Activity ◽  
Mountain Range ◽  
Stream Network ◽  
Mountainous Catchment ◽  
Isostatic Rebound ◽  
Base Level ◽  
Alluvial Terraces

Abstract. Alluvial megafans are sensitive recorders of landscape evolution, controlled by autogenic processes and allogenic forcing and influenced by the coupled dynamics of the fan with its mountainous catchment. The Lannemezan megafan in the northern Pyrenean foreland was abandoned by its mountainous feeder stream during the Quaternary and subsequently incised, leaving a flight of alluvial terraces along the stream network. We explore the relative roles of autogenic processes and external forcing in the building, abandonment and incision of a foreland megafan using numerical modelling and compare the results with the inferred evolution of the Lannemezan megafan. Autogenic processes are sufficient to explain the building of a megafan and the long-term entrenchment of its feeding river at time and space scales that match the Lannemezan setting. Climate, through temporal variations in precipitation rate, may have played a role in the episodic pattern of incision at a shorter time-scale. In contrast, base-level changes, tectonic activity in the mountain range or tilting of the foreland through flexural isostatic rebound appear unimportant.

scholarly journals A Structural-Thermal Model of the Karkonosze Pluton (Sudetes Mountains, SW Poland) for Hot Dry Rock (HDR) Geothermal Use

2016 ◽  
Vol 61 (4) ◽  
pp. 917-935 ◽  
Author(s):  
Wiesław Bujakowski ◽  
Antoni Barbacki ◽  
Maciej Miecznik ◽  
Leszek Pająk ◽  
Robert Skrzypczak
Keyword(s):  
Central Area ◽  
Tectonic Activity ◽  
Fluid Migration ◽  
Geothermal Resources ◽  
Radiogenic Heat ◽  
Cycle System ◽  
The Earth ◽  
Binary Cycle ◽  
Sw Poland ◽  
Insight Into

Abstract The main objective of this study was to develop a spatial temperature distribution of the Karkonosze Pluton to indicate optimum locations for HDR systems at drillable depth. HDR geothermal technology makes it possible to extract heat from the Earth in areas where no hydro-geothermal resources are present. To produce electricity in a binary cycle, system temperatures of > 100°C are usually required. In this paper, the authors have analysed the potential opportunities for applying HDR technology in the area of the Karkonosze Pluton, which is regarded as an optimum location for the application of the HDR concept (due to the potential for stimulation offered by the mechanical properties of the granites, radiogenic heat production, modern tectonic activity, and the thickness of the pluton). The model used in the analysis, which takes into account a hypothetical assessment of the manner and paths of fluid migration within the pluton, provides an insight into the spatial distribution of subsurface temperatures. It thus allows the location of relatively shallow high-temperature zones, which are optimal for the efficient application of HDR technology, to be identified. With respect to this technology, the Szklarska Poręba area and the NE part of the pluton seem to be better targets than the Cieplice central area, where the model indicated much lower temperatures (e.g. at a depth of 5,000 m, estimated temperatures in the vicinity of Szklarska Poręba were about 185°C and in the vicinity of Cieplice they were about 140°C).

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