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1.
The inception and growth of the active Carpino-Le Piane Basin Fault System (CLPBFS; central-southern Apennines, Italy) was analysed with respect to the neighbouring Isernia and Surrounding (ISFS) and Boiano Basin (BBFS) extensional Fault Systems. 39Ar–40Ar dating showed that the BBFS was already active 649 ± 21 ka bp and that the ISFS was active at least 476 ±10 ka bp , whereas the activity of the CLPBFS started certainly later than 253 ± 22 ka bp , and very probably as recently as <28 ka bp . These ages, combined with structural data (geometry and kinematics of the fault systems), indicate that the inception and development of the CLPBFS could be strictly related to the stress changes caused by earthquakes occurring on the BBFS. 相似文献
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Data recorded by the Italian Telemetered Seismic Network (ITSN) of the Istituto Nazionale di Geofisica (ING) have been widely used in recent years to image slab structures and to find evidence for active processes along the Italian Peninsula. However, the use of seismic data for geostructural purposes may be affected by the well-known trade-off between earthquake location and seismic-velocity parameters. Furthermore, the confidence ellipse predicted by standard procedures may be inadequate for the representation of the probable error of a computed localization. This paper evaluates the probable errors on the hypocentre determinations of the seismic events recorded by the ITSN, using a Monte Carlo method.
We compute synthetic arrival times using a 1-D velocity model appropriate as an average for the Italian area. The hypocentres used are all those recorded by the ITSN during the period January 1992 to March 1994 (1972 events). Station locations are those of the current ITSN configuration. The synthetic arrival times are perturbed with a Gaussian distribution of errors and input to ING's standard hypocentral location procedure, but using crustal velocities differing by 10 per cent from those used to generate them. Each simulation is repeated at least 30 times. Average absolute shifts of hypocentres are assessed in grid cells of linear dimension 33 km covering the whole Italian region.
For regions within the ITSN, shifts are typically 5–10 km in location and up to 20 km in depth. However, for offshore and coastal regions, they are much greater: 50 km or more in both location and depth (far exceeding the equivalent uncertainties quoted by ING bulletins). Possible consequences of this are highlighted by producing a cross-section of subcrustal hypocentres from the Adriatic to the Tyrrhenian Sea, where the large uncertainty in depth precludes any confident interpretation of dipping tectonic features. 相似文献
We compute synthetic arrival times using a 1-D velocity model appropriate as an average for the Italian area. The hypocentres used are all those recorded by the ITSN during the period January 1992 to March 1994 (1972 events). Station locations are those of the current ITSN configuration. The synthetic arrival times are perturbed with a Gaussian distribution of errors and input to ING's standard hypocentral location procedure, but using crustal velocities differing by 10 per cent from those used to generate them. Each simulation is repeated at least 30 times. Average absolute shifts of hypocentres are assessed in grid cells of linear dimension 33 km covering the whole Italian region.
For regions within the ITSN, shifts are typically 5–10 km in location and up to 20 km in depth. However, for offshore and coastal regions, they are much greater: 50 km or more in both location and depth (far exceeding the equivalent uncertainties quoted by ING bulletins). Possible consequences of this are highlighted by producing a cross-section of subcrustal hypocentres from the Adriatic to the Tyrrhenian Sea, where the large uncertainty in depth precludes any confident interpretation of dipping tectonic features. 相似文献
5.
It is generally accepted that the compositions and properties of soil organic matter (SOM) are influenced by many factors. In order to reveal the effects of soil texture on characteristics and dynamics of SOM and its sub-fraction, humic acid (HA), along two soil profiles, a yellow soil profile and a purplish soil profile, under the same climate and vegetation conditions were determined. Results indicate that the decomposition and humification degrees of SOM and HA of the purplish soils are higher than those of the corresponding yellow soils indicated by A/O–A ratios of HAs, TOCs and HA yields of bulk soil samples, nevertheless, the development degree of the purplish soil is lower than that of the yellow soil. The variations of E4/E6 ratios of HAs along the soil profiles indicate the overall molecular sizes of HAs decreased downward along the soil profiles. A/O–A ratios of HAs decreased downward along both the soil profiles indicate that humification processes decrease downward along both the soil profiles. Leaching of SOM shows significant effects on the distribution and characteristics of HAs in the yellow soil profile but the purplish soil profile, which is consistent with the higher hydrophobicity of HAs in purplish soils, shows that the distribution characteristics of SOM along the soil profiles are a complex result of the combination of soil texture and characteristics of SOM itself. The remarkably different sand contents are concluded tentatively as one of reasons to the different distributions and dynamics of HAs along the soil profiles, however, to profoundly understand the evolution and transport of SOM along soil profiles needs more researches. 相似文献
6.
Summary The aim of this study is to describe the behaviour of tropical dynamics in the ECHAM4 model when increased vertical resolution
around the tropopause and in the planetary boundary layer is used. In this work we perform experiments with the ECHAM4 model
using T30 horizontal resolution and 19 and 42 vertical levels. The impact of the increased vertical resolution on the simulation
of tropical clouds and precipitation has been investigated. Therefore, the dynamic fields related to tropical convection have
been analyzed.
The results suggest a beneficial effect of the increased number of vertical levels on the convective scheme performance and
on the related dynamic fields over the Tropics. The improvement of the rainfall climatologies in the 42-level model has been
explained via the impact of vertical resolution on the cloud structure. In the cloud spectrum of the L42 simulation, a third
peak appears around 600 hPa, revealing that when using higher vertical resolution the convective parametrization starts to
represent cumulus congestus clouds. 相似文献
7.
Effects of trace metal and exposure to air on serotonin and dopamine levels in tissues of the mussel Perna perna 总被引:1,自引:0,他引:1
We evaluated levels of serotonin (5HT) and dopamine (DOPA) in muscle and digestive glands of the mussel, Perna perna, collected at different times of day; exposed to air for 24 h, followed by re-submersion; and after exposure to different metals. Mussels collected at different periods of day showed little oscillation in 5HT and DOPA levels. Mussels exposed to metals showed significant changes in 5HT and DOPA levels in digestive gland and muscle, as did mussels exposed to air. Our data suggest that analyses of 5HT and DOPA in tissues of mussels could serve as a tool to evaluate the presence and effects of heavy metal contamination in mussels. Care in data interpretation is required, however, since other environmental factors such as exposure of mussels to air (i.e. at low tides) can also cause changes in DOPA and 5HT levels. Additional research is necessary to separate such natural environmental effects from effects of contaminants. 相似文献
8.
在扬子板块北缘城口明中剖面及巫溪徐家坝剖面下志留统龙马溪组底部的硅质岩、泥岩中发现椭球状重晶石结核。其矿物组成主要为重晶石颗粒与作为"基质"的黄铁矿、粘土矿物和石英。通过重晶石岩石学、矿物学及锶同位素分析表明,重晶石结核形成于早期成岩阶段松软沉积物的孔隙水中。上升洋流带来丰富的营养及富钡物质,表层海水的高初始生产力促使生物繁盛,海水中的钡通过生物作用富集形成生物钡,生物钡(bio-barite)在埋藏过程中的硫酸盐耗竭区(sulfate depleted zones)通过硫酸盐细菌作用(BSR)溶解被激活提供了钡的来源。围岩岩性(黑色泥岩和硅质泥岩)表明重晶石结核形成于缺氧的环境中。上述研究对深入理解早志留世时期扬子板块北缘古海洋环境有一定的启示作用。 相似文献
9.
Precise measurements of neutron star(NS) velocities provide critical clues in regard to the supernova physics and evolution of binary systems. Based on Gaia Data Release 2(DR2), we selected a sample of 24 young( 3 Myr) pulsars with precise parallax measurements and measured the velocity of their local standard of rest(LSR) and the velocity dispersion among their respective local stellar groups. The median velocity difference between thus calculated LSRs and the Galactic rotation model is ~ 7.6 km s~(-1),small compared to the typical velocity dispersion of ~ 27.5 km s~(-1). For pulsars off the Galactic plane,such differences grow significantly to as large as ~ 40 km s~(-1). More importantly, the velocity dispersion of stars in the local group of low-velocity pulsars can be comparable to their transverse velocities, suggesting that the intrinsic velocities of NS progenitors should be taken into account when we consider their natal kicks and binary evolution. We also examined the double NS system J0737-3039 A/B, and measured its transverse velocity to be 26_(-13)~(+18) km s~(-1) assuming nearby Gaia sources are representative of their birth environment. This work demonstrated the feasibility and importance of using Gaia data to study the velocity of individual systems and velocity distribution of NSs. 相似文献
10.
利用射线追踪法分析三种典型对流层映射函数在中国区域的精度 总被引:1,自引:0,他引:1
基于中国区域内8个气象站点2012年全年的探空数据,采用射线追踪法计算了各个站天顶方向至4°高度角区间内18个方向的对流层流体静力学和非流体静力学延迟量,将天顶延迟通过NMF、GMF和VMF1三种映射函数投影到各个高度角方向,与射线追踪法得出的延迟量进行比较,结果显示:①NMF有明显的季节性偏差,且精度与纬度存在强相关性;②VMF1的精度最高、稳定性最好,但在武汉、长沙等站点存在一定的季节性偏差;③GMF的精度介于NMF和VMF1之间。 相似文献