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61.
Rio Raharja Endra Gunawan Irwan Meilano Hasanuddin Z. Abidin Joni Efendi 《地震科学(英文版)》2016,29(5):291-298
The Java earthquake occurred on July 17,2006 with magnitude 7.8 associated to the subduction process of Indo-Australian plate and Sundaland block off southwestern coast of Java. We present postseismic deformation parameters of the 2006 Java earthquake analyzed using campaign GPS observation from 2006 to 2008 and continuous observation from 2007 to 2014. We use an analytical approach of logarithmic and exponential functions to model these GPS data. We find that the decay time in the order of hundreds of days after the mainshock as observed by 8 years' data after the mainshock for magnitude 7 earthquake is longer than a general megathrust earthquake event. Our findings suggest that the 2006 Java earthquake which is considered as ‘‘tsunami earthquake' most probably occurred in the region that has low rigidity and tends to continuously slip for long time periods. 相似文献
62.
Vincent J. Del Casino Jr. 《The Professional geographer》2013,65(3):407-421
In this article, I contribute to our understanding of the plurality of approaches that construct the geographies of health care through an examination of the distribution of health care services for people living with HIV/AIDS (PLWHA) in Chiang Mai Province, Thailand. In particular, I focus on the development of a network of support groups for PLWHA in order to examine the differences in the sociospatial organization of these groups, the practices of social actors participating in the groups' activities, and how these activities are mediated through place-based social relations. The first section of the article analyzes the spatial distribution of PLWHA support groups in relation to the distribution of AIDS cases over two time periods, 1994 and 1997. The second section goes below the surface of the spatial distribution, examining similarities and differences in PLWHA support groups through an analysis of survey data collected on thirty-five groups in 1997. The final section deepens this examination through an analysis of ethnographic data collected on the outreach efforts of one nongovernmental organization (NGO) and one PLWHA support group with which it worked. Each section offers opportunities for the extension of our understanding of the development of PLWHA support groups, their distribution in relation to the spread of AIDS cases, and their place-based meanings. 相似文献
63.
Rémy Thibaud Géraldine Del Mondo Thierry Garlan Ariane Mascret Christophe Carpentier 《Transactions in GIS》2013,17(5):742-762
Defining a model for the representation and the analysis of spatio‐temporal dynamics remains an open domain in geographical information sciences. In this article we investigate a spatio‐temporal graph‐based model dedicated to managing and extracting sets of geographical entities related in space and time. The approach is based on spatial and temporal local relations between neighboring entities during consecutive times. The model allows us to extract sets of connected entities distant in time and space over long periods and large spaces. From GIS concepts and qualitative reasoning on space and time, we combine the graph model with a dedicated spatial database. It includes information on geometry and geomorphometric parameters, and on spatial and temporal relations. This allows us to extend classical measurements of spatial parameters, with comparisons of entities linked by complex relations in space and time. As a case study, we show how the model suggests an efficient representation of dunes dynamics on a nautical chart for safe navigation. 相似文献
64.
Tiziana Di Lorenzo Mauro Brilli Dina Del Tosto Diana M. P. Galassi Marco Petitta 《Environmental Earth Sciences》2012,67(8):2383-2398
The aim of this study is to apply an integrated approach to determine nitrate sources and fate in the alluvial aquifer of the River Vibrata (Abruzzi, central Italy) by coupling the Isotope and the Component approaches. Collected data include concentration and nitrogen isotope composition of groundwater samples from the alluvial aquifer and nitrogen loads arising from agricultural and non-agricultural sources. The adopted methodology identified synthetic fertilizers as main sources of nitrate in the Vibrata alluvial aquifer. At the catchment scale, two different zones have been identified: the Upper Valley, where infiltration to groundwater is dominant and nitrogen easily migrates into the aquifer; in this area, nitrate content in groundwater is stable and normally higher than EU requirements. Moreover, streamwaters are fed by groundwater with a nitrate content likely lowered by denitrification processes occurring in the hyporheic zone. In the Lower Valley, runoff processes dominate and the nitrate content in surface waters is higher. Nevertheless, groundwater is locally affected by denitrification that breaks down the nitrate content, which often reaches values consistent with law limits. 相似文献
65.
The Aterno valley strong-motion array: seismic characterization and determination of subsoil model 总被引:1,自引:1,他引:0
G. Lanzo M. Tallini G. Milana G. Di Capua F. Del Monaco A. Pagliaroli S. Peppoloni 《Bulletin of Earthquake Engineering》2011,9(6):1855-1875
The paper focuses on the strong motion array deployed in the upper Aterno River Valley, in the immediate outskirts north-west
of the town of L’Aquila, which is part of the Italian Strong Motion Network operated by the Department of Civil Protection.
The array is composed of six accelerometric stations located along a cross section of the valley. The importance of this array
relies on the fact that a large amount of high-quality records were obtained during the 2009 L’Aquila seismic sequence, from
both the mainshock and several aftershocks. These data are especially important to investigate site effects in sediment-filled
valleys during moderate earthquakes in epicentral area because well-documented observational studies are very limited in the
literature. However, the main drawback for the study of site effects in the Aterno valley is the lack of a detailed knowledge
of the geometry of the valley, soil layering and dynamic properties of materials. The main motivation for this study stems
from the need to provide a reliable subsoil model of the valley coupled with high-quality strong motion data. Based on the
above, in the framework of S4 project, a major effort was undertaken to get a trustworthy cross section of the valley by an
ad hoc investigation, comprising geological and geotechnical surveys as well as an extensive geophysical campaign, characterized
by both active and passive measurements. These results were complemented by additional geological and geotechnical data available
in the literature. By merging all the information acquired, a 2D subsoil model of the transversal section of the upper Aterno
valley has been produced. The valley is characterised by an asymmetric shape with a shallower rock basement at the western
edge of the valley that deepens at the valley centre. Moreover, based on the results of geophysical tests, representative
Vs values were assigned to the different lithologic units forming the alluvial deposits filling the valley. Shear wave velocity
is a fundamental parameter for ground response studies and it is also effective in classifying the accelerometric station
from a seismic point of view. The 2D model may be therefore, considered a benchmark model for future studies of site effects.
It will offer the possibility to examine site effects with a complex underlying geology and to validate the results of numerical
simulations of site response analyses with the numerous observations from earthquake recordings, both for weak and strong
ground motion conditions. 相似文献
66.
Ali M. Rajabi Mohammad R. Mahdavifar M. Khamehchiyan V. Del Gaudio 《Natural Hazards》2011,59(2):1189-1203
Earthquake-induced landslides are responsible worldwide for significant socioeconomic losses and historically have a prominent
position in the list of natural hazards affecting the Iran plateau. As a step toward the development of tools for the assessment
and the management of this kind of hazard at regional scale, an empirical estimator of coseismic displacements along potential
sliding surfaces was obtained through a regression analysis for the Zagros region, a mountainous Iranian region subjected
to earthquake-induced landslides. This estimator, based on the Newmark’s model, allows to evaluate the expected permanent
displacement (named “Newmark displacement”) induced by seismic shaking of defined energy on potential sliding surface characterized
by a given critical acceleration. To produce regression models for Newmark
displacement estimators, a data set was constructed for different critical
acceleration values on the basis of 108 accelerometric recordings from 80 Iranian earthquakes with moment magnitudes between 3.6 and 7.
The empirical estimator has a general form, proposed by Jibson (Eng Geol 91:209–218, 2007), relating Newmark
displacement to Arias
intensity (as parameter representing the energy of the seismic forces) and to critical
acceleration (as parameter representing the dynamic shear resistance of the sliding mass). As an example of application, this relation
was employed to provide a basic document for earthquake-induced landslide hazard assessment at regional scale, according to
a method proposed by Del Gaudio et al. (Bull Seismol Soc Am 93:557–569, 2003), applied to the whole Iranian territory, including Zagros region. This method consists in evaluating the shear resistance
required to slopes to limit the occurrence of seismically induced failures, on the basis of the Newmark’s model. The obtained
results show that the exposure to landslide seismic induction is maximum in the Alborz Mountains region, where critical
accelerations up to ~0.1 g are required to limit the probability of seismic triggering of coherent type landslides within 10% in 50 years. 相似文献
67.
Riccardo Campana Marco Feroci Ettore Del Monte Teresa Mineo Niels Lund George W. Fraser 《Experimental Astronomy》2013,36(3):451-477
The Large Observatory For X-ray Timing (LOFT), currently in an assessment phase in the framework the ESA M3 Cosmic Vision programme, is an innovative medium-class mission specifically designed to answer fundamental questions about the behaviour of matter, in the very strong gravitational and magnetic fields around compact objects and in supranuclear density conditions. Having an effective area of ~10 m2 at 8 keV, LOFT will be able to measure with high sensitivity very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment is essential to assess the scientific performance of the mission and optimize the design of its main instrument, the Large Area Detector (LAD). In this paper the results of an extensive Geant-4 simulation of the instrumentwillbe discussed, showing the main contributions to the background and the design solutions for its reduction and control. Our results show that the current LOFT/LAD design is expected to meet its scientific requirement of a background rate equivalent to 10 mCrab in 2?30 keV, achieving about 5 mCrab in the most important 2–10 keV energy band. Moreover, simulations show an anticipated modulation of the background rate as small as 10 % over the orbital timescale. The intrinsic photonic origin of the largest background component also allows for an efficient modelling, supported by an in-flight active monitoring, allowing to predict systematic residuals significantly better than the requirement of 1 %, and actually meeting the 0.25 % science goal. 相似文献
68.
69.
Ciro Del Negro Luigi Fortuna Alexis Herault Annamaria Vicari 《Bulletin of Volcanology》2008,70(7):805-812
Since the mechanical properties of lava change over time, lava flows represent a challenge for physically based modeling.
This change is ruled by a temperature field which needs to be modeled. MAGFLOW Cellular Automata (CA) model was developed
for physically based simulations of lava flows in near real-time. We introduced an algorithm based on the Monte Carlo approach
to solve the anisotropic problem. As transition rule of CA, a steady-state solution of Navier-Stokes equations was adopted
in the case of isothermal laminar pressure-driven Bingham fluid. For the cooling mechanism, we consider only the radiative
heat loss from the surface of the flow and the change of the temperature due to mixture of lavas between cells with different
temperatures. The model was applied to reproduce a real lava flow that occurred during the 2004–2005 Etna eruption. The simulations
were computed using three different empirical relationships between viscosity and temperature. 相似文献
70.
Alberto?RenzulliEmail author Stefano?Del?Moro Michele?Menna Patrizia?Landi Marco?Piermattei 《Bulletin of Volcanology》2009,71(7):795-813
We describe the mineralogy, geochemistry, and mesomicrostructure of fresh subvolcanic blocks erupted during the 5 April 2003
paroxysm of Stromboli (Aeolian Islands, Italy). These blocks represent ∼50 vol.% of the total erupted ejecta and consist of
fine- to medium-grained basaltic lithotypes ranging from relatively homogeneous dolerites to strongly or poorly welded magmatic
breccias. The breccia components are represented by angular fragments of dolerites entrapped in a matrix of vesiculated (lava-like
to scoriae) crystal-rich (CR) basalt. All of the studied blocks are cognates with the CR basalt of the normal Strombolian
activity or lavas and they are often coated by a few-centimeter thick layer of crystal-poor (CP) basaltic pumice erupted during
the paroxysm. We suggest that they result from the rapid increase of pressure and related subvolcanic rock failure that occurred
shortly before the 5 April 2003 explosion, when the uppermost portion of the edifice inflated and suffered brecciation as
the result of the sudden rise of the gas-rich CP basalt that triggered the eruption. Dolerites and magmatic matrix of the
breccias show major and trace element compositions that match those of the CR basalts erupted during normal Strombolian activity
and effusive events at Stromboli volcano. Dolerites consist of (a) phenocrysts normally found in the CR basalts and (b) late-stage
magmatic minerals such as sanidine, An60-28 plagioclase, Fe–Mn-rich olivines (Fo68-48), phlogopite, apatite, and opaque mineral pairs (magnetite and ilmenite), most of which are never found both in lava flows
and scoriae erupted during the persistent explosive activity that characterizes typical Strombolian behavior. Subvolcanic
crystallization of the Stromboli CR magma, leading to slowly cooled equivalents of basalts, could result from transient drainage
of the magma from the summit craters to lower levels. Fingering and engulfing of the material that collapsed from the summit
crater floor into the shallow basaltic system during the late evening of 28 December 2002 coupled with the short break in
the summit persistent explosions between December 2002 and March 2003 permitted the CR magma pockets to solidify as dolerites,
which were confined to the uppermost portion of the system and thus not involved in the ongoing flank effusive activity. Crystal
size distribution of the basaltic blocks and crystallization of the finer-grained (<0.1 mm) mafic minerals of the dolerites
over a time interval of ∼100 days closely agrees with the above interpretation. Vesicle filling (miarolitic cavities) locally
found in some dolerites, with minerals deposited as vapor-phase crystallization is a result of continuous gas percolation
through the rocks of the uppermost portion of the volcanic system. Poorly welded magmatic breccias formed during syn-eruptive processes of 5 April 2003, when the paroxysm strongly shattered the shallow subvolcanic system and many dolerite
fragments were entrapped in the CR magma. In contrast, the high degree of welding between the dolerite clasts and the CR basaltic
matrix in the strongly welded magmatic breccias provides a snapshot of subvolcanic intrusions of the CR basalt into the dolerite
when, after a 2-month break in activity, CR magmas started to rise again to the summit craters. Blocks similar to these subvolcanic
ejecta of 5 April 2003 were also erupted during previous paroxysms (e.g., 1930) suggesting that changes in the usual Strombolian
activity (e.g., short breaks in the persistent mild explosions and/or flank effusive activity) lead to transient crystallization
of dolerites in the shallow plumbing system. 相似文献