A comparison of seismic risk maps for Italy   总被引：5，自引：3，他引：2  

Helen Crowley  Miriam Colombi  Barbara Borzi  Marta Faravelli  Mauro Onida  Manuel Lopez  Diego Polli  Fabrizio Meroni  Rui Pinho 《Bulletin of Earthquake Engineering》2009,7(1):149-180

National seismic risk maps are an important risk mitigation tool as they can be used for the prioritization of regions within a country where retrofitting of the building stock or other risk mitigation measures should take place. The production of a seismic risk map involves the convolution of seismic hazard data, vulnerability predictions for the building stock and exposure data. The seismic risk maps produced in Italy over the past 10 years are compared in this paper with recent proposals for seismic risk maps based on state-of-the-art seismic hazard data and mechanics-based vulnerability assessment procedures. The aim of the paper is to open the discussion for the way in which future seismic risk maps could be produced, making use of the most up-to-date information in the fields of seismic hazard evaluation and vulnerability assessment.  相似文献   

Magnetic susceptibility logging of Chicxulub proximal impact breccias in the Santa Elena borehole: implications for emplacement mode     

Jaime Urrutia-Fucugauchi  Ligia Pérez-Cruz  Sara E. Campos-Arriola  Elia Escobar-Sánchez  Miriam Velasco-Villarreal 《Studia Geophysica et Geodaetica》2014,58(1):100-120

Magnetic susceptibility logging is used to study the impact breccias in the Chicxulub crater. The basic premise is that the high contrasts in magnetic properties can be used to characterize the breccias. The Santa Elena borehole was drilled 110 km radial distance from crater center and sampled a 172 m thick sequence of impact breccias, between 332 and 504 m depth. Breccia units are distinguished from differences in composition, size, and relative contents of clasts, type of matrix and textural and lithological assemblages, which can be resolved in the susceptibility logs. The whole-core log shows characteristic variation patterns with high, intermediate and low susceptibilities. High resolution logging of matrix and clasts records the heterogeneous nature of impactites, with higher variability at smaller spatial scales. Measurements confirm that diamagnetic susceptibilities characterize the carbonate clasts, high susceptibilities the basement granitic clasts and intermediate values the silicate melt-rich and silicate-poor matrix. Intermediate variable susceptibilities characterize breccias rich in melt particles. Correlation of matrix and clast logs with whole-core log shows that signal is controlled by the matrix. Logs for clast shows a discrete distribution with peaks of intermediate to high values, which correlate with large clast distributions. The ejecta blanket includes the fallback suevites rich in silicate melt particles and shocked minerals, the high temperature vapor deposits from ejecta curtain collapse and high velocity basal flows, and the carbonate rich deposits from lateral basal flows and secondary cratering. Late fallback suevites record minor turbulent conditions resulting from progressive cooling of the ejecta plume.  相似文献   

Impact of pond aquaculture effluents on seagrass performance in NE Hainan,tropical China     

Lucia S. Herbeck  Miriam Sollich  Daniela Unger  Marianne Holmer  Tim C. Jennerjahn 《Marine pollution bulletin》2014

The impact of pond aquaculture effluents on the distribution and performance of seagrasses was examined in NE Hainan, tropical China. Samples were taken along transects in three back-reef areas with different extent of aquaculture production in their hinterland. High δ¹⁵N in seagrass leaves and epiphytes (6–9‰) similar to values in pond effluents documented aquaculture as dominant nitrogen source in the back-reefs with decreasing impact with distance from shore. Seagrass species abundance, shoot density and biomass were lower and concentrations of nutrients, chlorophyll and suspended matter were higher at nearshore sites with high and moderate pond abundance than at the control site. High epiphyte loads and low δ³⁴S in seagrass leaves suggest temporal shading and sulphide poisoning of the nearshore seagrasses. Observed gradients in environmental parameters and seagrass performance indicate that the distance from the pond outlets and size of the adjacent pond agglomeration are major determinants of seagrass degradation.  相似文献   

A Field Experiment on Dust Emission by Wind Erosion in the Taklimakan Desert   总被引：4，自引：1，他引：3       下载免费PDF全文

YANG Xinghu  HE Qing  ALI Mamtimin  HUO Wen  LIU Xinchun  STRAKE Miriam 《Acta Meteorologica Sinica》2012,26(2):241-249

Dust emission by wind erosion in surface is a serious problem in many arid regions around the world,and it is harmful to the ecological environment,human health,and social economy.To monitor the characteristics of saltation activity and to calculate the threshold wind velocity and sediment discharge under field conditions have significance on the research of dust emission by wind erosion.Therefore,a field experiment was conducted over the flat sand in the hinterland of the Taklimakan Desert.One sampling system was installed on the flat sand surface at Tazhong,consisting of a meteorological tower with a height of 2 m,a piezoelectric saltation sensor(Sensit),and a Big Spring Number Eight(BSNE) sampler station.Occurrence of saltation activity was recorded every second using the Sensit.Each BSNE station consisted of five BSNE samplers with the lowest sampler at 0.05 m and the highest sampler at 1.0 m above the soil surface.Sediment was collected from the samplers every 24 h.It is found that saltation activity was detected for only 21.5% of the hours measured,and the longest period of saltation activity occurring continuously was not longer than 5 min under the field conditions.The threshold wind velocity was variable,its minimum value was 4.9 m s 1,the maximum value was 9.2 m s 1,and the average value was 7.0 m s 1.The threshold wind velocity presented a positive linear increase during the measurement period.The observation site had a sediment discharge of 82.1 kg m 1 over a period of 24 h.Based on hourly saltation counts,hourly sediment discharge was estimated.Overall,there was no obvious linear or other functional relationship between the hourly sediment discharge and wind velocity.The results show that the changes of sediment discharge do not quite depend on wind velocity.  相似文献   

An improved permeability model of coal for coalbed methane recovery and CO2 geosequestration     

G.X. Wang  P. Massarotto  V. Rudolph 《International Journal of Coal Geology》2009,77(1-2):127-136

An alternative approach is proposed to develop an improved permeability model for coalbed methane (CBM) and CO₂-enhanced CBM (ECBM) recovery, and CO₂ geosequestration in coal. This approach integrates the textural and mechanical properties to describe the anisotropy of gas permeability in coal reservoirs. The model accounts for the stress dependent deformation using a stress–strain correlation, which allows determination of directional permeability for coals. The stress–strain correlation was developed by combining mechanical strain with sorption-induced strain for any given direction. The mechanical strain of coal is described by the general thermo-poro-elastic constitutive equations for solid materials under isothermal conditions and the sorption-induced strain is approximated by treating the swelling/shrinkage of coal matrix equivalent to the thermal contraction/expansion of materials. With directional strains, the permeability of coal in any given direction can be modeled based on the theory of rock hydraulics. In this study, the proposed model was tested with both literature data and experiments. The experiments were carried out using a specially designed true tri-axial stress coal permeameter (TTSCP). The results show that the proposed model provides better predictions for the literature data compared with other conventional coal permeability models. The model also gives reasonable agreement between the predicted and measured stress–strains and directional permeabilities under laboratory conditions.  相似文献   

Intercomparison of instruments for tropospheric measurements using differential optical absorption spectroscopy     

C. Camy-Peyret  B. Bergovist  B. Galle  M. Carleer  C. Clerbaux  R. Colin  C. Fayt  F. Goutail  M. Nunes-Pinharanda  J. P. Pommereau  M. Hausmann  U. Platt  I. Pundt  T. Rudolph  C. Hermans  P. C. Simon  A. C. Vandaele  J. M. C. Plane  N. Smith 《Journal of Atmospheric Chemistry》1996,23(1):51-80

The results of an intercomparison campaign of eight different long path UV-visible DOAS instruments measuring NO₂, O₃ and SO₂ concentrations in a moderately polluted urban site are presented. For effective optical path lengths of 230 and 780 m the overall spread of these measurements (±1) are 5×10¹⁰, 6×10¹⁰ and 1×10¹⁰ molec·cm^-3 (2.0, 2.4, and 0.4 ppb) for these molecules respectively when all instruments used a common set of absorption cross sections. The remaining differences are not completely random and the systematic differences are attributed to the different retrieval methods used for each instrument.  相似文献   

Peroxyacetyl Nitrate (PAN) Measurements During the POPCORN Campaign     

W. Schrimpf  K. Linaerts  K. P. Müller  R. Koppmann  J. Rudolph 《Journal of Atmospheric Chemistry》1998,31(1-2):139-159

During the POPCORN campaign between 3 and 24 August 1994 we measured peroxyacetyl nitrate (PAN) in a rural area of Mecklenburg-Vorpommern (North-Eastern Germany) above a corn field. A total of about 5000 PAN measurements were carried out within the three weeks of the campaign. Measured PAN mixing ratios ranged from below the detection limit of 10 ppt up to an afternoon maximum of 1 ppb. The mean value of all data was 140 ppt. The daily mean PAN mixing ratios were typically in the range of 50 to 250 ppt, but during a clean air episode PAN mixing ratios of well below 40 ppt were observed. The characteristic relative diurnal variation of the PAN mixing ratios with a late night/early morning minimum and an afternoon maximum persisted during these episodes. The daily averages of the PAN mixing ratios showed clear episodic variations which coincided with the duration of typical synoptic episodes of two to six days duration. Based on the measurements of the various parameters determining the PAN formation and destruction rates, the local budget for PAN was calculated. During daytime the calculated net photochemical formation rate of PAN was nearly always significantly higher than the observed change of the PAN concentration. This demonstrates that substantial amounts of PAN (often in the range of several hundred ppt/h) were exported from the corn field. The resulting removal of NOx to some extent effects the budget of nitrogen oxides (NOx), but the export of odd oxygen radicals in the form of PAN during daytime often amounted up to 30–50% of the OH-radical formation by ozone photolysis. Thus the importance of PAN as reservoir and transport medium for odd oxygen radicals can be very substantial and may have a significant impact on the budget and distribution of odd oxygen radicals.  相似文献   

The contribution of authigenic feldspars to the geochemical balance of alkali metals     

Miriam Kastner 《Geochimica et cosmochimica acta》1974,38(4):650-653

About 5 per cent of all feldspars in sediments are authigenic. This amounts to 0·94 per cent of the total sedimentary mass. At least 2.1 × 10¹⁸ kg Na and 3.4 × 10¹⁸kg K have been removed from sea water by reconstitution of authigenic feldspars in the total mass of surviving sediments. Consequently, 9.3 × 10¹⁹ moles CO₂ have been released by the formation of authigenic albite and 8.8 × 10¹⁹ moles CO₂ by the formation of authigenic K-feldspar.  相似文献   

The magnetic effects of brecciation and shock in meteorites: III. The achondrites     

Aviva Brecher  Miriam Fuhrman  Judy Stein 《Earth, Moon, and Planets》1979,20(3):265-279

We present results of a magnetic survey of achondritic meteorites, representing the aubrites (A), diogenites (D), Irowardites (H), and eucrites (E) groups and relate their magnetic behavior to respective class characteristics and models of origin.Magnetic susceptibility (x) values cluster well within each group and decrease systematically between groups (from 2 to 0.1×10^–3GOe^–1 cm^–3), with the average metal contents, (from 1 to <0.1 wt%) in the above order. The natural remanent magnetization (NRM) values range broadly within each group, but group averages decrease roughly as above. However, the considerable within-sample and intra-group variability in NRM level and its demagnetization characteristics attest to inhomogeneous and localized brecciation effects. Although petrological-chemical studies resolve a primary component of magmatic differentiation on the planetoid of origin, no clear magnetic record of such event has been preserved. The magnetization of achondrites is mainly the product of their complex, multi-stage impact brecciation and metamorphism history, in accord with other lines of evidence.The magnetic behavior of achondrites is remarkably similar to that characteristic of lunar breccias and impact-melt rocks and reinforces their analogous mode of genesis, as brought out by chemical and petrographic analyses.  相似文献   

Detection Capability of Selected Seismic Stations in Central Europe     

Kristeková  Miriam  Skáčiková  Iveta 《Studia Geophysica et Geodaetica》1997,41(2):149-163

The 50% and 90% P-wave detection thresholds of 3 Austrian, 2 Czech, 5 German, 1 Hungarian and 3 Slovak seismic stations have been determined for four intervals of epicentral distances by a direct method using the maximum-likelihood technique. The USGS-NEIC Earthquake Data Reports covering the period from January 1990 to November 1994 were used as the reference system. The seismic stations Kaperské Hory (KHC, Czech Republic) and Collmberg (CLL, Germany) are the stations with the best detection capabilities for all investigated intervals of epicentral distances.  相似文献