Magma characterization of the Mexican volcanic belt (Mexico)     

S. Pal  M. Lopez  J. Perez  D. J. Terrell 《Bulletin of Volcanology》1978,41(4):379-389

Over 330 bulk chemical analyses of rocks (Oligocene or Miocene to Recent) from the Mexican Volcanic Belt (MVB) have been compiled. These analyses all together represent a calc-alkaline sequence of continental margin type. The North-Eastern part of the Belt seems to overlap with another volcanic province, namely. Eastern Cordillera in which magmas are mostly of alkaline sequence. A model involving fractional crystallization as the principal mechanism is proposed for magma genesis in the MVB.  相似文献   

Evaluation of simulated ground motions for predicting elastic response of long period structures and inelastic response of structures     

Anil K. Chopra  Oscar A. Lopez 《地震工程与结构动力学》1979,7(4):383-402

The response of linear elastic and non-linear hysteretic systems having a single degree of freedom to recorded and simulated ground motions is studied. The objective is to evaluate whether the commonly used simulated motions are appropriate for predicting inelastic response of structures and elastic response of long period structures. Eight simulated motions were generated to model properties of horizontal ground motions recorded during four earthquakes. The simulated motions are sample functions of a stationary, Gaussian white noise process, multiplied by a temporal intensity function and passed through a linear single-degree-of-freedom filter. Two versions, corresponding to parabolic and ‘standard’ base line corrections (BLC), of each of the simulated and recorded accelerograms were considered. The following general conclusions are deduced. Simulated ground motions should be subjected to the standard BLC, because it results in more reliable ground velocities and displacements, which in turn would lead to more reliable predictions of response of long period structures. Furthermore, the spectral density of the underlying random process, from which the simulated motions are obtained, should be modified to be more representative of the frequency content of recorded motions, especially in the low frequency range. Such an improved model can be expected to lead to better agreement, over a broad range of periods, in the average response spectra of simulated and recorded motions, for elastic as well as inelastic systems.  相似文献   

Oceanographic studies supporting the assessment of deep-sea disposal of defueled decommissioned nuclear submarines     

G. Ross Heath  David K. Rea  Gordon Ness  R. Dale Pillsbury  Thomas M. Beasley  Carlos Lopez  Daniel M. Talbert 《Environmental Geology》1984,6(4):189-199

Based on criteria developed by the international Atomic Energy Agency (IAEA), potential disposal sites for defueled, decommissioned nuclear submarines appear to exist in deep water south of the Mendocino Fracture Zone within 200 nautical miles of the United States Oceanographic measurements in the water column and at the sea floor in a study area (W-N) at 39 5°N, 127 5°W will allow the operational and radiological consequences of deep-sea disposal to be compared with land burial of old submarines. The W-N studies also are yielding new data that will provide insights to the deposition and early diagenesis of distal hemipelagic sediments Royalty-free reproduction of this article by the U S Government or by the authors for U S. Government purposes is permitted.  相似文献   

Pa andSa waves and the upper mantle     

Dr. Markus Båth  Dr. Alfonso Lopez Arroyo 《Pure and Applied Geophysics》1963,56(1):67-92

Summary This investigation is based on records of 96 earthquakes withPa andSa written by the Press-Ewing instruments at Uppsala in the interval June 1961–December 1962.Pa andSa waves are observed for all earthquake regions, irrespective of distance, focal depth or path properties. They have significantly higher velocities under continents than under oceans, which demonstrates corresponding differences in the upper mantle. Continental velocities are 8.35 km/sec (Pa) and 4.56 km/sec (Sa), oceanic velocities 8.01 km/sec (Pa) and 4.45 km/sec (Sa). The most frequent periods are 10 sec (Pa) and 20 sec (Sa). They are independent of distance forPa but increase with distance forSa. The best developedPa andSa are obtained for earthquakes at focal depths less than about 60 km. The particle motion ofSa may be anything from pureSV to pureSH motion and has high correlation to the particle motion ofS. The apparent angles of emergence (in average 51° forPa and 54° forSa) vary with distance. On the basis of our observations it is suggested thatPa andSa propagate by multiple reflections under grazing incidence under the Moho discontinuity.

---

Zusammenfassung Die vorliegende Untersuchung gründet sich auf die Registrierungen von 96 Erdbeben mitPa- undSa-Wellen, die mit Hilfe der Press-Ewing Instrumente zu Uppsala im Zeitraum Juli 1961–Dezember 1962 aufgenommen wurden. DiePa- undSa-Wellen sind für alle seismischen Regionen beobachtet worden, unabhängig von Entfernung, Herdtiefe oder Wellenweg. Sie haben bedeutend höhere Geschwindigkeiten unter den Kontinenten als unter den Ozeanen, was einen entsprechenden Unterschied im oberen Erdmantel beweist. Die kontinentalen Geschwindigkeiten betragen 8.35 km/sec (Pa) und 4.56 km/sec (Sa), die ozeanischen Geschwindigkeiten 8.01 km/sec (Pa) und 4.45 km/sec (Sa). Die am häufigsten vorkommenden Perioden betragen 10 sec (Pa) und 20 sec (Sa). Sie sind unabhängig von der Entfernung fürPa aber wachsen mit der Entfernung fürSa. Die am besten entwickeltenPa- undSa-Wellen werden für Erdbeben mit kleinerer Herdtiefe als rund 60 km beobachtet. FürSa wird jede beliebige Orbitalbewegung zwischenSV undSH beobachtet. Sie hat eine hohe Korrelation mit der Orbitalbewegung vonS. Die scheinbaren Emergenzwinkel (durchschnittlich 51° fürPa und 54° fürSa) variieren mit der Entfernung. Auf Grund unserer Beobachtungen wird die Hypothese aufgestellt, dass sich diePa-undSa-Wellen durch Mehrfachreflexionen, bei tangentialem Einfall, unter der Moho-Diskontinuität ausbreiten.

---

Resumen La presente investigación está basada en los sismogramas de 96 terremotos, que muestranPa ySa, registrados por los sismógrafos de Uppsala (Press-Ewing), durante el periodo Junio 1961 a Diciembre 1962. Las fasesPa ySa se observan en todas las regiones sismicas, independientemente de la distancia, de la profundidad focal ó de las propiedades de la trayectoria. Tienen velocidades significativamente mayores bajo continentes que bajo los océanos, lo que demuestra la existencia de diferencias en el manto superior. Las velocidades continentales son 8.35 km/seg (Pa) y 4.56 km/seg (Sa) y las oceánicas 8.01 km/seg (Pa) y 4.45 km/seg (Sa). Los periodos mas frecuentes son 10 segundos paraPa y 20 segundos paraSa. Tales periodos son independientes de la distancia en el caso dePa pero crecen con ella paraSa. Las fasesPa ySa mejor desarrolladas se obtienen para terremotos cuya profundidad focal es inferior a los 60 kilómetros. El movimiento de la particula del suelo debido aSa puede ser de cualquier tipo, desde puroSV a puroSH, y muestra gran correlación con el movimiento de la particula deS. Los ángulos de emergencia aparentes (de promedio 51° paraPa y 54° paraSa) varian con la distancia. Basándonos en nuestras observaciones sugerimos quePa ySa se propagan por reflexión múltiple, bajo incidencia rozante bajo la discontinuidad de Mohorovii.

  相似文献   

Industrial Contamination of a Municipal Water-Supply Lake by Induced Reversal of Ground-Water Flow, Managua, Nicaragua     

David N. Bethune  R. N. Farvolden  M. Cathryn Ryan  res Lopez Guzman 《Ground water》1996,34(4):699-708

  相似文献   

Factors controlling stratal pattern and facies distribution of fluvio‐lacustrine sedimentation in the Sivas mini‐basins,Oligocene (Turkey)          下载免费PDF全文

Charlotte Ribes  Charlie Kergaravat  Philippe Crumeyrolle  Michel Lopez  Cédric Bonnel  André Poisson  Kaan S. Kavak  Jean‐Paul Callot  Jean‐Claude Ringenbach 《Basin Research》2017,29(Z1):596-621

The Sivas Basin, located in the Central Anatolian Plateau of Turkey, is a foreland basin that records a complex interaction between sedimentation, salt tectonics and regional shortening during the Oligo‐Miocene leading to the formation of numerous mini‐basins. The Oligocene sedimentary infill of the mini‐basins consists of a thick continental succession, the Karayün Formation, comprising a vertical succession of three main sub‐environments: (i) playa‐lake, (ii) fluvial braided, and (iii) saline lacustrine. These sub‐environments are seen as forming a large Distributive Fluvial System (DFS) modified through time as a function of sediment supply and accommodation related to regional changes in climate and tectonic regime. Within neighbouring mini‐basins and despite a similar vertical stratigraphic succession, subtle variations in facies assemblages and thickness are observed in stratigraphic units of equivalent age, thus demonstrating the local control exerted by halokinesis. Stratigraphic and stratal patterns reveal in great detail the complex interaction between salt tectonics and sedimentation including different types of halokinetic structures such as hooks, wedges and halokinetic folds. The regional variations of accommodation/sediment supply led to coeval changes in the architectural patterns recorded in the mini‐basins. The type of accommodation regime produces several changes in the sedimentary record: (i) a regime dominated by regional accommodation limits the impact of halokinesis, which is recorded as very small variations in stratigraphic thickness and facies distribution within and between mini‐basins; (ii) a regime dominated by localized salt‐induced accommodation linked to the subsidence of each individual mini‐basin enhances the facies heterogeneity within the DFS, causing sharp changes in stratigraphic thickness and facies assemblages within and between mini‐basins.  相似文献   

Soil chemical alteration due to slaughterhouse waste application as identified by spectral reflectance in São Paulo State,Brazil: an environmental monitoring useful tool     

José A. M. Demattê  Julianne de Castro Oliveira  Tiago Rodrigues Tavares  Leonardo Ramirez Lopez  Fabrício da Silva Terra  Suzana Romeiro Araújo  Caio Troula Fongaro  Stoécio Malta Ferreira Maia  Francisco Fujita de Castro Mello  Rodnei Rizzo  Simone Vicente  Marco Antonio de Melo Bortolleto  Pedro Henrique Ramos Cerqueira 《Environmental Earth Sciences》2016,75(18):1277

  相似文献   

Sliding fragility of block‐type non‐structural components. Part 2: Restrained components     

D. Lopez Garcia  T. T. Soong 《地震工程与结构动力学》2003,32(1):131-149

This paper focuses on seismic vulnerability assessment of restrained block‐type non‐structural components under sliding response on the basis of seismic inputs specified by current seismic codes. The general representation of restrained equipment considered in this study consists of a rigid block restrained by four post‐tensioned, symmetrically arranged cables. Two sliding‐related failure modes are considered: restraint breakage and excessive absolute acceleration. Fragility analysis is proposed as an appropriate tool to evaluate these failure modes. Sample fragility curves developed through Monte‐Carlo simulations show that the restraint breakage limit state is sensitive to the parameters of the equation of motion. For instance, fragility estimates obtained without taking into account vertical base accelerations can be significantly unconservative for relatively large values of the coefficient of friction. In contrast, the excessive absolute acceleration limit state exhibits little sensitivity to the parameters of the equation of motion. Peak absolute acceleration response is almost always equal to or greater than the horizontal peak base acceleration. Representative results suggest that reasonable response estimates for blocks located at stories other than the ground in multistorey buildings can in general be obtained by simply scaling the ground acceleration to the peak acceleration at the corresponding storey. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Taking Better Advantage of Fold Axis Data to Characterize Anisotropy of Complex Folded Structures in the Implicit Modeling Framework     

Pizzella  Laure  Alais  Robin  Lopez  Simon  Freulon  Xavier  Rivoirard  Jacques 《Mathematical Geosciences》2022,54(1):95-130

Mathematical Geosciences - When too few field measurements are available for the geological modeling of complex folded structures, the results of implicit methods typically exhibit an...  相似文献   

Post-processing of sequential indicator simulation realizations for modeling geologic bodies     

Jorge Kazuo Yamamoto  Paulo Milton Barbosa Landim  Antonio Tadashi Kikuda  Claudio Benedito Baptista Leite  Santiago Diaz Lopez 《Computational Geosciences》2015,19(1):257-266

  相似文献