Seismic rupture during the 1960 Great Chile and the 2010 Maule earthquakes limited by a giant Pleistocene submarine slope failure     

Jacob Geersen  David Völker  Jan H. Behrmann  Dirk Kläschen  Wilhelm Weinrebe  Sebastian Krastel  Christian Reichert 《地学学报》2013,25(6):472-477

Determining factors that limit coseismic rupture is important to evaluate the hazard of powerful subduction zone earthquakes such as the 2011 Tohoku‐Oki event (Mw = 9.0). In 1960 (Mw = 9.5) and 2010 (Mw = 8.8), Chile was hit by such powerful earthquakes, the boundary of which was the site of a giant submarine slope failure with chaotic debris subducted to seismogenic zone depth. Here, a continuous décollement is absent, whereas away from the slope failure, a continuous décollement is seismically imaged. We infer that underthrusting of inhomogeneous slide deposits prevents the development of a décollement, and thus the formation of a thin continuous slip zone necessary for earthquake rupture propagation. Thus, coseismic rupture during the 1960 and 2010 earthquakes seems to be limited by underthrusted upper plate mass‐wasting deposits. More generally, our results suggest that upper plate dynamics and resulting surface processes can play a key role for determining rupture size of subduction zone earthquakes.  相似文献   

Frequency and intensity of high-altitude floods over the last 3.5 ka in northwestern French Alps (Lake Anterne)     

Charline Giguet-Covex  Fabien Arnaud  Dirk Enters  Jérôme Poulenard  Laurent Millet  Pierre Francus  Fernand David  Pierre-Jérôme Rey  Bruno Wilhelm  Jean-Jacques Delannoy 《Quaternary Research》2012,77(1):12-22

In central Western Europe, several studies have shown that colder Holocene periods, such as the Little Ice Age, also correspond to wet periods. However, in mountain areas which are highly sensitive to erosion processes and where precipitation events can be localized, past evolution of hydrological activity might be more complicated. To assess these past hydrological changes, a paleolimnological approach was applied on a 13.4-m-long sediment core taken in alpine Lake Anterne (2063 m asl) and representing the last 3.5 ka. Lake sedimentation is mainly composed of flood deposits triggered by precipitation events. Sedimentological and geochemical analyses show that floods were more frequent during cold periods while high-intensity flood events occurred preferentially during warmer periods. In mild temperature conditions, both flood patterns are present. This underlines the complex relationship between flood hazards and climatic change in mountain areas. During the warmer and/or dryer times of the end of Iron Age and the Roman Period, both the frequency and intensity of floods increased. This is interpreted as an effect of human-induced clearing for grazing activities and reveals that anthropogenic interferences must be taken into account when reconstructing climatic signals from natural archives.  相似文献   

Die Formen der Kantenkiesel     

Geh. San.-Rat Dr. Wilhelm Pfannkuch 《International Journal of Earth Sciences》1914,5(4):247-252

Ohne Zusammenfassung  相似文献   

Stratigraphie und Tektonik des Hochlandes von Costa-Rica     

Wilhelm Lohmann 《International Journal of Earth Sciences》1934,25(1):10-26

Ohne Zusammenfassung  相似文献   

Physical properties of rocks from the upper part of the Yaxcopoil‐1 drill hole,Chicxulub crater     

Y. Popov  R. Romushkevich  I. Bayuk  D. Korobkov  S. Mayr  H. Burkhardt  H. Wilhelm 《Meteoritics & planetary science》2004,39(6):799-812

Abstract— Physical properties were determined in a first step on post‐impact tertiary limestones from the depth interval of 404–666 m of the Yaxcopoil‐1 (Yax‐1) scientific well, drilled in the Chicxulub impact crater (Mexico). Thermal conductivity, thermal diffusivity, density, and porosity were measured on 120 dry and water‐saturated rocks with a core sampling interval of 2–2.5 m. Nondestructive, non‐contact optical scanning technology was used for thermal property measurements including thermal anisotropy and inhomogeneity. Supplementary petrophysical properties (acoustic velocities, formation resisitivity factor, internal surface, and hydraulic permeability) were determined on a selected subgroup of representative samples to derive correlations with the densely measured parameters, establishing estimated depth logs to provide calibration values for the interpretation of geophysical data. Significant short‐ and long‐scale variations of porosity (1–37%) turned out to be the dominant factor influencing thermal, acoustic, and hydraulic properties of this post impact limestone formation. Correspondingly, large variations of thermal conductivity, thermal diffusivity, acoustic velocities, and hydraulic permeability were found. These variations of physical properties allow us to subdivide the formation into several zones. A combination of experimental data on thermal conductivity for dry and water‐saturated rocks and a theoretical model of effective thermal conductivity for heterogeneous media have been used to calculate thermal conductivity of mineral skeleton and pore aspect ratio for every core under study. The results on thermal parameters are the necessary basis for the determination of heat flow density, demonstrating the necessity of dense sampling in the case of inhomogeneous rock formations.  相似文献   

Comparison of petrophysical properties of impactites for four meteoritic impact structures     

Y. Popov  S. Mayr  R. Romushkevich  H. Burkhardt  H. Wilhelm 《Meteoritics & planetary science》2014,49(5):896-920

We reanalyzed and compared unique data sets, which we obtained in the frame of combined petrophysical and geothermal investigations within scientific drilling projects on four impact structures: the Puchezh–Katunki impact structure (Vorotilovo borehole, Russia), the Ries impact structure (Noerdlingen‐73 borehole, Germany), the Chicxulub impact structure (ICDP Yaxcopoil‐1 borehole, Mexico), and the Chesapeake impact structure (ICDP‐USGS‐Eyreville borehole, USA). For a joined interpretation, we used the following previously published data: thermal properties, using the optical scanning technique, and porosities, both measured on densely sampled halfcores of the boreholes. For the two ICDP boreholes, we also used our previously published P‐wave velocities measured on a subset of cores. We show that thermal conductivity, thermal anisotropy, porosity, and velocity can be correlated with shock metamorphism (target rocks of the Puchezh–Katunki and Ries impact structures), and confirm the absence of shock metamorphism in the samples taken from megablocks (Chicxulub and Chesapeake impact structure). The physical properties of the lithic impact breccias and suevites are influenced mainly by their impact‐related porosity. Physical properties of lower porosity lithic impact breccias and suevites are also influenced by their chemical composition. These data allow for a distinction between different types of breccias due to differences concerning the texture and chemistry and the different amounts of melt and rock clasts.  相似文献   

Observations of Polar Plumes with the Sumer Instrument on Soho     

D. M. Hassler  K. Wilhelm  P. Lemaire  U. Schühle 《Solar physics》1997,175(2):375-391

We present new observations of O vi 1032 Å line profiles in polar plumes, and inter-plume regions, on the disk and above the limb in the north coronal hole obtained with the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument on the SOHO (Solar and Heliospheric Observatory) spacecraft. On 22 May 1996, a 5 x 5 arc min spectroheliogram was scanned above the north polar coronal hole with the entrance slit extending from 1.03 to 1.33 solar radii with 1.5 arc sec spatial resolution and ≈ 0.044 Å per pixel spectral resolution in the wavelength range 1020–1040 Å. Detailed plume structure in O vi 1032 Å can be seen extending beyond 1.3 solar radii, with intensities in the plume regions 10–50% brighter, but line widths 10–15% narrower, than the inter-plume regions. Possible explanations for this observed anti-correlation between line width and intensity in the plume and inter-plume regions are discussed. We conclude that the source of the high-speed solar wind may not be polar plumes, but the inter-plume lanes associated with open magnetic field regions of the chromospheric network.  相似文献   

High resolution temperature measurements in the borehole Yaxcopoil‐1, Mexico     

H. Wilhelm  P. Heidinger  J. &#x;afanda  V. ermk  H. Burkhardt  Yu. Popov 《Meteoritics & planetary science》2004,39(6):813-819

Abstract— Within the frame of the International Continental Deep Drilling Program (ICDP) and as a part of the Chicxulub Scientific Drilling Project (CSDP), high resolution temperature measurements were performed in the borehole Yaxcopoil‐1 (Yax‐1). The temperature was logged to the depth of 858 m seven times between March 6–19, 2002, starting 10 days after the hole was shut in and mud circulation ceased. Successive logs revealed only small temperature variations in time and space, indicating a fast temperature recovery to almost undisturbed conditions prior to the first log. From these logs, a mean temperature gradient of ～37 mK/m was determined below the uppermost 250 m. Another temperature log was recorded on May 24, 2003 (15 months after the shut in) to a depth of 895 m. The obtained temperature profile is very similar to the 2002 profile, with an insignificantly higher mean gradient below 250 m that may indicate a long‐term return to the pre‐drilling temperature. The temperature in the uppermost part of the hole bears signs of considerable influence of a convective contribution to the vertical thermal heat transfer. The depth extent of the convection seems to have deepened from 150 m in March 2002 to 230 m in May 2003. Based on the observed temperature gradient and the rock types encountered in the borehole above 670 m, the conducted heat flow is expected to be in the range 65–80 mW/m².  相似文献   

Influence of sample location and livestock numbers on Sporormiella concentrations and accumulation rates in surface sediments of Lake Allos, French Alps     

David Etienne  Bruno Wilhelm  Pierre Sabatier  Jean-Louis Reyss  Fabien Arnaud 《Journal of Paleolimnology》2013,49(2):117-127

Spores of coprophilous fungi, especially Sporormiella, are often well preserved in lake sediment cores. It has been hypothesized that such spores can be used to quantify past livestock abundance. The quantitative relationship between fungal spore abundance and livestock populations, however, is not well established, nor are the mechanisms of spore transport and deposition in lacustrine systems. Multiple cores from Lake Allos, a large high-elevation lake in the French Alps, were used to map the modern abundance of Sordaria and Sporormiella spores throughout the lake. We observed high spatial heterogeneity with respect to spore numbers. No correlation with the distance from shoreline was found. There was, however, a relation with distance from the two main lake inlets. These results were used to select two fungi-rich sediment cores to investigate grazing pressure over the last two centuries. Comparisons were made between spore influx and historic data on livestock densities in the catchment. A sharp decrease in Sporormiella influx ca. 1894–1895 was associated with a reported reduction in sheep in the Allos catchment at that time. Mean influx of Sporormiella decreased by a factor of three between the nineteenth and twentieth centuries, reflecting a reduction in the reported number of animals in the Lake Allos catchment, from 6,000 to 2,000. This study confirmed that Sporormiella spore abundance in lake sediments can be used as a proxy for catchment herbivore numbers in paleoecological reconstructions. Nevertheless, our data indicate that before spore accumulation can be used to infer past domestic herbivore density, one must understand the processes of coprophilous spore transfer from the catchment to the lake and the influence of core location on spore numbers in the sediment.  相似文献   

Erratum to: Assessing the strength of regional changes in near-surface climate associated with a global warming of 2°C     

Wilhelm May 《Climatic change》2012,110(3-4):645-647

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