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681.
Comparing different models of aftershock rate decay: The role of catalog incompleteness in the first times after main shock 总被引:2,自引:0,他引:2
We evaluated the efficiency of various models in describing the time decay of aftershock rate of 47 simple sequences occurred in California (37) from 1933 to 2004 and in Italy (10) from 1976 to 2004. We compared the models by the corrected Akaike Information Criterion (AICc) and the Bayesian Information Criterion (BIC), both based on the log-likelihood function and also including a penalty term that takes into account the number of independent observations and of free parameters of each model. These criteria follow two different approaches (probabilistic and Bayesian respectively) well covering the wide spectra of current views on model comparison. To evaluate the role of catalog incompleteness in the first times after the main shock, we compared the performance of different models by varying the starting time Ts and the minimum magnitude threshold Mmin for each sequence. We found that Omori-type models including parameter c are preferable to those not including it, only for short Ts and low Mmin while the latters generally perform better than the formers for Ts longer than a few hours and Mmin larger than the main shock magnitude Mm minus 3 units. For Ts > 1 day or Mmin > Mm − 2.5, only about 15% of the sequences still give a preference to models including c. This clearly indicates that a value of parameter c different from zero does not represent a general property of aftershock sequences in California and Italy but it is very likely induced in most cases by catalog incompleteness in the first times after the main shock. We also considered other models of aftershock decay proposed in the literature: the Stretched Exponential Law in two forms (including and not including a time shift) and the band Limited Power Law (LPL). We found that such models perform worse than the Modified Omori Model (MOM) and other Omori-type models for the large majority of sequences, although for LPL, the relatively short duration of the analyzed sequences (one year) might also contribute to its poor performance. Our analysis demonstrates that the MOM with c kept fixed to 0 represent the better choice for the modeling (and the forecasting) of simple sequence behavior in California and Italy. 相似文献
682.
Isabelle Coutand † Barbara Carrapa† Anke Deeken‡ Axel K. Schmitt§ Edward R. Sobel† Manfred R. Strecker† 《Basin Research》2006,18(1):1-26
The arid Puna plateau of the southern Central Andes is characterized by Cenozoic distributed shortening forming intramontane basins that are disconnected from the humid foreland because of the defeat of orogen‐traversing channels. Thick Tertiary and Quaternary sedimentary fills in Puna basins have reduced topographic contrasts between the compressional basins and ranges, leading to a typical low‐relief plateau morphology. Structurally identical basins that are still externally drained straddle the eastern border of the Puna and document the eastward propagation of orographic barriers and ensuing aridification. One of them, the Angastaco basin, is transitional between the highly compartmentalized Puna highlands and the undeformed Andean foreland. Sandstone petrography, structural and stratigraphic analysis, combined with detrital apatite fission‐track thermochronology from a ~6200‐m‐thick Miocene to Pliocene stratigraphic section in the Angastaco basin, document the late Eocene to late Pliocene exhumation history of source regions along the eastern border of the Puna (Eastern Cordillera (EC)) as well as the construction of orographic barriers along the southeastern flank of the Central Andes. Onset of exhumation of a source in the EC in late Eocene time as well as a rapid exhumation of the Sierra de Luracatao (in the EC) at about 20 Ma are recorded in the detrital sediments of the Angastaco basin. Sediment accumulation in the basin began ~15 Ma, a time at which the EC had already built sufficient topography to prevent Puna sourced detritus from reaching the basin. After ~13 Ma, shortening shifted eastward, exhuming ranges that preserve an apatite fission‐track partial annealing zone recording cooling during the late Cretaceous rifting event. Facies changes and fossil content suggest that after 9 Ma, the EC constituted an effective orographic barrier that prevented moisture penetration into the plateau. Between 3.4 and 2.4 Ma, another orographic barrier was uplifted to the east, leading to further aridification and pronounced precipitation gradients along the mountain front. This study emphasizes the important role of tectonics in the evolution of climate in this part of the Andes. 相似文献
683.
Lawrence V. Stanislawski Kornelijus Survila Jeffrey Wendel Yan Liu Barbara P. Buttenfield 《制图学和地理信息科学》2018,45(4):319-328
This paper describes a workflow for automating the extraction of elevation-derived stream lines using open source tools with parallel computing support and testing the effectiveness of procedures in various terrain conditions within the conterminous United States. Drainage networks are extracted from the US Geological Survey 1/3 arc-second 3D Elevation Program elevation data having a nominal cell size of 10 m. This research demonstrates the utility of open source tools with parallel computing support for extracting connected drainage network patterns and handling depressions in 30 subbasins distributed across humid, dry, and transitional climate regions and in terrain conditions exhibiting a range of slopes. Special attention is given to low-slope terrain, where network connectivity is preserved by generating synthetic stream channels through lake and waterbody polygons. Conflation analysis compares the extracted streams with a 1:24,000-scale National Hydrography Dataset flowline network and shows that similarities are greatest for second- and higher-order tributaries. 相似文献
684.
Ettore Vidotto Rainer Helmig Martin Schneider Barbara Wohlmuth 《Computational Geosciences》2018,22(6):1487-1502
In this paper, we present a fast streamline-based numerical method for the two-phase flow equations in high-rate flooding scenarios for incompressible fluids in heterogeneous and anisotropic porous media. A fractional flow formulation is adopted and a discontinuous Galerkin method (DG) is employed to solve the pressure equation. Capillary effects can be neglected in high-rate flooding scenarios. This allows us to present an improved streamline approach in combination with the one-dimensional front tracking method to solve the transport equation. To handle the high computational costs of the DG approximation, domain decomposition is applied combined with an algebraic multigrid preconditioner to solve the linear system. Special care at the interior interfaces is required and the streamline tracer has to include a dynamic communication strategy. The method is validated in various two- and three-dimensional tests, where comparisons of the solutions in terms of approximation of flow front propagation with standard fully implicit finite-volume methods are provided. 相似文献
685.
Barbara Sophia Koelbl Machteld A. van den Broek André P. C. Faaij Detlef P. van Vuuren 《Climatic change》2014,123(3-4):461-476
Carbon Capture and Storage (CCS) can be a valuable CO2 mitigation option, but what role CCS will play in the future is uncertain. In this paper we analyze the results of different integrated assessment models (IAMs) taking part in the 27th round of the Energy Modeling Forum (EMF) with respect to the role of CCS in long term mitigation scenarios. Specifically we look into the use of CCS as a function of time, mitigation targets, availability of renewables and its use with different fuels. Furthermore, we explore the possibility to relate model results to general and CCS specific model assumptions. The results show a wide range of cumulative capture in the 2010–2100 period (600–3050 GtCO2), but the fact that no model projects less than 600 GtCO2 indicates that CCS is considered to be important by all these models. Interestingly, CCS storage rates are often projected to be still increasing in the second half of this century. Depending on the scenario, at least six out of eight, up to all models show higher storage rates in 2100 than in 2050. CCS shares in cumulative primary energy use are in most models increasing with the stringency of the target or under conservative availability of renewables. The strong variations of CCS deployment projection rates could not be related to the reported differences in the assumptions of the models by means of a cross-model comparison in this sample. 相似文献
686.
Enrico Pirotta Barbara Eva Laesser Andrea Hardaker Nicholas Riddoch Marianne Marcoux David Lusseau 《Marine pollution bulletin》2013
The exponential growth of the human population and its increasing industrial development often involve large scale modifications of the environment. In the marine context, coastal urbanisation and harbour expansion to accommodate the rising levels of shipping and offshore energy exploitation require dredging to modify the shoreline and sea floor. While the consequences of dredging on invertebrates and fish are relatively well documented, no study has robustly tested the effects on large marine vertebrates. We monitored the attendance of common bottlenose dolphins (Tursiops truncatus) to a recently established urbanised foraging patch, Aberdeen harbour (Scotland), and modelled the effect of dredging operations on site usage. We found that higher intensities of dredging caused the dolphins to spend less time in the harbour, despite high baseline levels of disturbance and the importance of the area as a foraging patch. 相似文献
687.
688.
Fadi Chaaban Hanan Darwishe Barbara Louche Yvonne Battiau-Queney Eric Masson Jamal El Khattabi Erick Carlier 《Environmental Earth Sciences》2012,65(1):183-193
The use of geographic information system (GIS) minimizes the effort and improves the efficiency of numerical models. The GIS
provides a platform for high capacity collection, management, manipulation, analysis, modeling and display of spatial data.
The conceptual model is created using GIS objects including points, arcs and polygons so that it can accurately represent
real world condition. According to the research problem, the geographical model is based on Hypergraph Based Data Structure
method, and a conceptual data model has been created from which a physical data model was elaborated in ArcGIS9.3 platform.
The groundwater modeling system (GMS) provides a powerful tool for hydrodynamics modeling and it is able to solve complex
problems such as the groundwater flow and seawater intrusion. The sand-dune system of Hardelot-Plage (North of France) suffers
from a lack of well-developed foredune. This problem is linked to the almost constant saturation of beach sand which is the
potential source of dune nourishment. In the south of Hardelot, the coastline is slowly, but constantly retreating. To remedy
this situation, a coupling between a GIS and GMS was adopted, in order to find the possible scenarios which could lower the
piezometric surface in the concerned area and allow dune nourishment again. The GMS used supports the Modflow-2000 code. A
direct approach to designing Modflow finite difference model is tedious and less intuitive, specifically for complex boundary
and initial conditions. Therefore, a Modflow model can be developed either using a grid or conceptual model approach. The
preparation of input data modeling is tedious and takes a long time. The model created in GMS was calibrated against the historical
and observed water level data for 1995–2006. Then a hydrodispersive model (MT3d code in GMS) was launched for evaluating sea-water
intrusion. The model was run to generate groundwater and salt concentration scenario during pumping tests. 相似文献
689.
690.