Earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w. Quaternary Fault and Fold Database of the United States 2019-03-10

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Earthquakes at North

earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w

The transfer function can be best explained by a simple model in which the oceanic lithosphere is treated as a thin elastic plate overlying a weak fluid. The photograph is taken by the Russian seismologist Olga Pavlenko. Upper right hand corner is inside the Fennoscandian Shield, and in the lower left corner we are outside the shield. It was very important to bring together information from these fields, and further multidisciplinary coopera tion is therefore strongly encouraged for the future. Voss Geological Survey of Denmark and Greenland, Ostervoldgade 10, 1350 Copenhagen K, Denmark Correspondence to: S. We use cookies to enhance your experience on our website.

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Earthquakes at North

earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w

Due to the position of the Vestnesa Ridge with respect to the Molloy and Knipovich mid-ocean ridges, it has been suggested that seepage along the ridge has a tectonic control. Irregularities have been found and evaluated in a number of papers for Norway e. Geological Survey Coal Investigations Map C-122-B, 1 sheet, scale 1:100,00. The preferred focal mechanism based on waveform modeling implies nearly pure normal faulting on a roughly east-west striking plane. Reconstructing the Late Quaternary loading histories of active faults by exploring continental climate archives will be essential in order to better understand past and future strain release patterns of seismogenic faults and to evaluate their seismic hazard.

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Evolution of the Arctic — North Atlantic Rift System

earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w

Comparison of geodetic and geologic data from the Wasatch region, Utah, and implications for the spectral character of Earth deformation at periods of 10 to 10 million years. We determined the source process of the 1994 Northridge earthquake in relation to the aftershock mechanisms. It formed on the palaeoslope of the regional Jelgava Depression, which represents an elongated axial region of the deepest part of the Ordovician Baltoscandian sedimentary basin. The work was checked and further revised in 2001 in connection with a commercial hazard study. We have shown that loads applied on Earth's surface exert a fundamental control on the rate of strain accumulation on individual normal faults.

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Earthquakes Along the Passive Margin of Greenland: Evidence for Postglacial Rebound Control

earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w

Along the margin, stress directions also indicate a possible connection to postglacial uplift as well as to lithospheric loading effects. A primary regional focus of DynaQlim is the study of cratonic areas of northern Canada and Scandinavia. Map of the earthquake geography in Scandinavia covering the years from January 1970 to December 2004. This report cannot do justice to all of the detailed presentations; therefore we will mention some highlights that caught the attention of the writers and present some general conclusions that were drawn a t the workshop. The assessment is less certain, but falls to improbable when concerning 4 proposed palaeo-earthquakes by Hallandsåsen in south-western Sweden. Series Title: , Series C,, Mathematical and physical sciences ;, 266. The source parameters of two earthquakes that occurred under Baffin Island, Canada, were determined from surface wave spectrum analysis.

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Evolution of the Arctic — North Atlantic Rift System

earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w

Consequently, earthquakes concentrate along the plate boundary faults, and show quasi-periodic occurrences, although the actual temporal patterns are often complicated. The view, as seen during the field trip, convinces that a rock slide has disturbed the metre high steps of the numbered beach ridges 6 to 9. A program of deep continental drilling within the Timiskaming Graben and extension of the current program of investigating lake-floor geology across the many lakes of the Western Québec Seismic Zone are now needed. Time-predictable recurrence model for large earthquakes. The model predicts a strike-slip stress regime in regions with pockmarks where acoustic flares have not been documented. The modelled changes in slip rate confirm the theoretical prediction of the response of normal faults to the application and removal of a load.

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Summary, Conclusions and Recommendations

earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w

Relatively low estimates of the elastic thickness were obtained for the Emperor Seamounts north of 40°N, and relatively high estimates for the Emperor Seamounts south of 40°N and the Hawaiian Ridge. Note that the horizontal scale differs from Fig. However, the width of the flexural uplift increases to approximately 120 km for an elastic thickness of 10 km compared to 15 km for Airy isostasy, which matches the width of the granite body. The seismicity picture as presented in Figs. I first present results of temperature calculations performed for all subduction zones for which adequate data on seismicity, relative plate motion and age of the descending oceanic lithosphere exist. We analysed the distribution of intraplate seismicity and its correlation with several geophysical lithospheric parameters in an attempt to establish which factors might promote or inhibit the occurrence of intraplate earthquakes.

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enigmatic Bala earthquake of 1974

earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w

He demonstrated the methods with a seismic hazard analysis for the North Sea. An estimate of the rupture length, about 2 km, was also possible. The coincidence of aerial lights and an earthquake may seem curious, so it is worth quickly visiting the alternative explanations that could avoid such a coincidence. Larsen, personal communication, 2009; O. More abundant seepage on the eastern Vestnesa Ridge at present may be facilitated by the dilation of faults and fractures favourably oriented with respect to the stress field.

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Slip rate variations on normal faults during glacial

earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w

Two decades of oil and gas exploration have produced large quantities of seismic reflection profiles that have been searched for evidence of structurally significant faults. In several papers it is argued that there is no correlation between the uplift pattern and the pattern of earthquake locations e. The high stress drop may relate to the relatively long earthquake repeat time in the region. We propose that earthquake-prone areas with these favourable conditions correspond to regions of weakened lithosphere, where most of the regional lithospheric stresses are supported by the overlying brittle upper crust. No fault plane solution could be obtained. In the European scale the Tornquist Zone is considered as present-day inactive, as presented in conference proceedings by Gregersen et al. A metre-scale thick siltstone—sandstone lobe is described within the Dapingian outer ramp argillaceous limestone facies of the Baltoscandian palaeobasin.

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Spatial Correlation between Seismicity and Postglacial Rebound in Eastern Canada

earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w

The present topography is convincingly a succession of coastal terraces, which display a recent geological evolution explained in great detail by Hansen 1977, 1980, 1986a, b, 1994 and 1995 and followed up in recent further investigations Hansen et al. In the presence of the entire load, the slip rate is 0. Seismicity along the Boothia Uplift — Bell Arch, which is a positive basement trend across the Canadian Shield, was probably rejuvenated by glacial loading centres that flanked both sides of this curvilinear trend. Using crustal stresses inferred from earthquake focal mechanisms, Seth Stein Northwestern University suggested a spatially varying stress field across the eastern Canadian margin and concluded that, in addition to the plate driving forces, deglaciation is at least partially responsible for the earthquakes. Rosenkrantz, 1937; Nielsen and Thybo, 2004; Solid Earth, 5, 109—118, 2014 112 S. And even more improbable, subsidence and uplift several times as suggested in the book by Hansen 1994 is not a possibility. Previous efforts to study this earthquake employed different subsets of the available data and did not reach a consensus regarding the focal mechanism, although all agree that there was a significant component of normal slip involved.

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EARTHQUAKES AT AND NEAR NORTH ATLANTIC PASSIVE MARGINS: NEOTECTONICS AND POST

earthquakes at north atlantic passive margins neotectonics and postglacial rebound gregersen sren basham peter w

The paper by Baartman 1975 spoke about structural differences. Note that the four faults are located in the centre of the region affected by isostatic rebound , and strike subparallel to the eastern margin of Lake Bonneville. The intraplate earthquake zones in north-eastern and in northern Greenland are situated as linear continuations of the plate boundaries near the bend of the mid ocean ridge close to Station Nord, between Spitzbergen and Greenland. A very basic remark in assessing these observations is that a comparison with the surroundings is necessary. In the first experiment, we performed two model runs, one without loading and one in which a spatially uniform load, equivalent to 500 m of ice, is applied on top of the model.

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