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Marco Olivieri 《Journal of Seismology》2013,17(2):607-614
Rapid magnitude estimate procedures represent a crucial part of proposed earthquake early warning systems. Most of these estimates are focused on the first part of the P-wave train, the earlier and less destructive part of the ground motion that follows an earthquake. Allen and Kanamori (Science 300:786–789, 2003) proposed to use the predominant period of the P-wave to determine the magnitude of a large earthquake at local distance and Olivieri et al. (Bull Seismol Soc Am 185:74–81, 2008) calibrated a specific relation for the Italian region. The Mw 6.3 earthquake hit Central Italy on April 6, 2009 and the largest aftershocks provide a useful dataset to validate the proposed relation and discuss the risks connected to the extrapolation of magnitude relations with a poor dataset of large earthquake waveforms. A large discrepancy between local magnitude (ML) estimated by means of $\tau_p^{{\rm max}}$ evaluation and standard ML (6.8 ± 1.5 vs. 5.9 ± 0.4) suggests using caution when ML vs. $\tau_p^{{\rm max}}$ calibrations do not include a relevant dataset of large earthquakes. Effects from large residuals could be mitigated or removed introducing selection rules on τ p function, by regionalizing the ML vs. $\tau_p^{{\rm max}}$ function in the presence of significant tectonic or geological heterogeneity, and using probabilistic and evolutionary methods. 相似文献
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On Sunday, October 23rd, 2011, the Van province, in the Eastern Turkey, was stricken by a magnitude $\text{ M}_{\mathrm{w}} \!=\! 7.1$ earthquake. The maximum horizontal peak ground acceleration, i.e. 0.182 g, was measured from the seismic station in Muradiye, at about 40 km from the epicenter. Several $\text{ M}_\mathrm{w} > 5.7$ strong motion aftershocks were recorded in November 2011. The exceptionally rich sequence of ground motions was due to the dense seismotectonic activity of the Eastern Turkey, where many active historical faults exist and newly generated can also be found because of the ongoing continental collision between the Arabian and the Eurasian Plates. The 2011 Van earthquake sequence caused 644 casualties, 1966 injuries with 252 rescues; the total economic losses are estimated at around 1 billion US dollars. The present paper deals with the seismological and structural damage assessment of two major seismic events and aftershock sequences in Van region; special emphasis is on the findings of the site investigations performed in the aftermath of the major seismic event. The performed investigation has shown that there is substantial field evidence demonstrating that the losses generated to the local social communities were caused by typical structural and non-structural deficiencies that have been surveyed in the past in several moderate-to-major earthquakes worldwide, especially in poor countries. Comprehensive numerical simulations were also carried out to assess the characteristics of the strong motion records and their effects on existing representative building type of structures in the earthquake-affected region. It was found that the local building stock is highly vulnerable and requires urgent major structural interventions for seismic strengthening. A cost-efficient retrofitting scheme is however not straightforward. It should be a trade-off between two competing aspects: the use of innovative materials and technologies on one hand, and the low-quality of the workmanships and lack of adequate quality control during construction phase, which are available in the Van province, on the other hand. 相似文献
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Barite, an important component of offshore drilling muds, is shown to adversely affect the ctenidia of the suspension feeding bivalve, Cerastoderma edule and the deposit feeder, Macoma balthica. SEM observations showed that exposure to barite caused cilia to shorten and coagulate, and, in some extreme cases, cause the disintegration of the gill structure itself. Using a simple ciliary condition index (CCI) the impact of the barite was quantified and damage rates expressed. The bivalves were treated with daily doses of 1, 2, and 3-mm depth equivalents of barite. In all treatments significant damage to the gills was recorded although, in the case of the 1-mm dose rate, this did not occur for 4 days. In the other two treatments, damage was apparent within a day of exposure with 100% mortality occurring within 12 days. Macoma balthica appeared slightly more tolerant of exposure to barite than C. edule. 相似文献
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Paola Monaco Filippo Santucci de Magistris Salvatore Grasso Silvano Marchetti Michele Maugeri Gianfranco Totani 《Bulletin of Earthquake Engineering》2011,9(1):231-261
This paper describes a case-history of liquefaction occurred near the village of Vittorito after the April 6, 2009 L’Aquila
earthquake (moment magnitude Mw = 6.3), approximately 45 km far from the epicentre. In the document, first, an estimation of the seismic motion in the area
has been made. Thereafter, the performed geotechnical investigation is described, followed by the application of some fast
assessment criteria for the occurrence of liquefaction, recently proposed by the new Italian Building Code. A careful assessment
of all the parameters involved in conventional Seed and Idriss (1971) liquefaction analyses is considered. The cyclic resistance ratio CRR is evaluated by cone penetration tests CPT and by in
situ seismic dilatometer tests SMDT; in the latter case CRR is evaluated by different empirical correlations with shear wave
velocity Vs and horizontal stress index KD. Analytical data confirmed the observed occurrence of the liquefaction in Vittorito, even if the acceleration field in the
area, produced by the L’Aquila earthquake, was very low. 相似文献
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Jarle Berntsen Lie-Yauw Oey Tal Ezer Richard Greatbatch Huijie Xue Yasumasa Miyazawa 《Ocean Dynamics》2014,64(10):1531-1534
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Edit Thamó-Bozsó Gábor Csillag László I. Fodor Pál M. Müller Attila Nagy 《Quaternary Geochronology》2010,5(2-3):120-124
Fluvial, colluvial, and aeolian sediments were dated by optically stimulated luminescence (OSL) on quartz to improve the chronological framework for Quaternary sedimentation and landscape evolution in the forelands of the Vértes Hills (central Hungary). The separated quartz was suitable for age determination based on an OSL SAR protocol. Most samples have asymmetric equivalent dose distributions and OSL ages were calculated by the mean, central, and minimum De values. Considering geomorphology and earlier age data from the area, the central De values seem most appropriate for age calculation. A fan on the geomorphological level QV in the western foreland of the Vértes Hills was deposited 79–75 (±8) ka ago. In the south-eastern foreland an alluvial fan on level QIIb is at most 42 ± 4 ka old. Fluvial incision and aggradation occurred 16–10 (±1) ka ago on the geomorphic surface QIIa. Loess is 14 ± 1 ka old, and slope sedimentation was active 11–9 (±1) ka ago. Our OSL data demonstrate that in the north-western foreland of the Vértes Hills wind remained an important agent after the last glacial times, into the early Holocene (9–8 ± 1 ka) and was able to accumulate large aeolian dunes. 相似文献
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WANG Shangqi & PENG Jinlan Nanjing Institute of Geology Palaeontology Chinese Academy of Sciences Nanjing China 《中国科学D辑(英文版)》2005,48(10)
In South China and its adjacent areas, leperditiid ostracodes from the Devonian are very abundant. They have in common a trailing chevron muscle scar (tv: Fig. 1(a)) which uninterruptedly extends ventrally with passing geological time, and range through most De-vonian. The tribe Sinoleperditiini was proposed by Wang (1994) for these ostracodes since other leperdi-tiids from North America, Europe, Siberia and else-where bear the non-trailing chevron muscle scar (v: Fig. 1(b)) and range from… 相似文献
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Re-Os (ICP-MS) dating of the massive sulfide ores from the Jinchuan Ni-Cu-PGE deposit 总被引：4，自引：0，他引：4
YANG Gang DU Andao LU Jiren QU Wenjun & CHEN Jiangfeng . National Research Center of Geoanalysis Beijing China . Laboratory for Earth Material Cycling School of Earth Space Sciences University of Science Technology of China Hefei China . Institute of Mineral Resource Chinese Academy of Geological Sciences Beijing China 《中国科学D辑(英文版)》2005,48(10)
The Jinchuan Ni-Cu-PGE deposit is the largest nickel sulfide deposit in China and the third largest in the world[1]. It is also the largest platinum deposit in China and contains about 60% platinum reserve of China[2]. The Jinchuan intrusion covers only an area of 1.34 km2, but 47.8% of its volume is the orebody. That makes Jinchuan a typical “large ore deposit in a small intrusion”. A number of research works has been car-ried out towards the Jinchuan deposit. Different ore-forming mo… 相似文献
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INTRODUCTIONAs registered by the seismic network of the China Earthquake Administration and the regionalnetworkof Xizang(Tibet) Autonomous Region,anMS5·7 earthquaketook place between Bomi countyand Medog county, Tibet on August 18 , 2003·The China Earthquake Administration sent anearthquake site investigation team to the stricken region immediately after the earthquake . Theinvestigationteamconsistedjointly of personnel fromthe Earthquake Administration of Xizang (Tibet)Autonomo… 相似文献
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Otávio Cristiano Montanher Evlyn Márcia Leão de Morais Novo Edvard Elias de Souza Filho 《水文科学杂志》2013,58(13-14):1901-1912
ABSTRACTWe discuss the claim that the Amazon River has been subjected to a noticeable increase in suspended sediment transport (SST) in response to both climate and land-use changes. To study this, both satellite imagery and in situ data were compiled to produce a 32-year time series (1984–2016) of suspended sediment concentration. Both parametric and nonparametric statistics were applied to examine the SST time trend. The results indicate that there has been no statistically significant increase in SST in the last 32 years, independent of the statistical approach. The results indicate that, over the last 32 years at the Óbidos station, in Brazil, a recurring pattern of increase and decrease in SST has occurred, rather than a unidirectional systematic trend. This further explains the increasing trend reported in the literature and indicates that short time series are not recommended for time trend analyses due to the large inter-annual variability. 相似文献
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ZHANG Xiaohui WANG Hui & LI Tiesheng Key Laboratory of Lithosphere Tectonic Evolution Institute of Geology Geophysics Chinese Academy of Sciences Beijing China 《中国科学D辑(英文版)》2005,48(5)
As for the metamorphic rock series distributed on the “Faku Faulted Convex (FFC)”[1] of the northern Liaoning, the earliest geologic investigation divided it into the Langzishan, Dashiqiao and Gaixian forma-tions1) and considered it to be equivalent to the Liaohe Group in the eastern Liaoning, whereas Liaoning Bu-reau of Geology and Mineral Resources (LBGMR) included it into the Lower Proterozoic basement[1]. Recent 1︰50000 scale geological mapping2) reveals that this deformed and … 相似文献
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Natural-water chemistry in the interfluve of the Enzor’yakhi and the Yun’yakhi rivers (the eastern slope of the Polar Urals) is characterized in terms of the ratios of major ions belonging to hydrocarbonate calcium-magnesium and magnesium-calcium chemical types. From the viewpoint of evolution of the water-rock system in the region, five geochemical types of water were identified by the degree of their equilibrium with secondary minerals, reflecting different formation conditions of their chemistry. A specific feature of the region is the formation of waters of organogenic geochemical type, which are considerably enriched by organic matter, determining the specifics of migration of some chemical elements in such waters. 相似文献
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We estimate (/T)
P
of the lower mantle at seismic frequencies using two distinct approaches by combining ambient laboratory measurements on lower mantle minerals with seismic data. In the first approach, an upper bound is estimated for |(/T)
P
| by comparing the shear modulus () profile of PREM with laboratory room-temperature data of extrapolated to high pressures. The second approach employs a seismic tomography constraint ( lnV
S
/ lnV
P
)
P
=1.8–2, which directly relates (/T)
P
with (K
S
/T)
P
. An average (K
S
/T)
P
can be obtained by comparing the well-established room-temperature compression data for lower mantle minerals with theK
S
profile of PREM along several possible adiabats. Both (K
S
/T) and (/T) depend on silicon content [or (Mg+Fe)/Sil of the model. For various compositions, the two approaches predict rather distinct (/T)
P
vs. (K
S
/T)
P
curves, which intersect at a composition similar to pyrolite with (/T)
P
=–0.02 to –0.035 and (K
S
/T)
P
=–0.015 to –0.020 GPa/K. The pure perovskite model, on the other hand, yields grossly inconsistent results using the two approaches. We conclude that both vertical and lateral variations in seismic velocities are consistent with variation due to pressure, temperature, and phase transformations of a uniform composition. Additional physical properties of a pyrolite lower mantle are further predicted. Lateral temperature variations are predicted to be about 100–250 K, and the ratio of ( lnp/ lnV
S
)
P
around 0.13 and 0.26. All of these parameters increase slightly with depth if the ratio of ( lnV
S
/ lnV
P
)
P
remains constant throughout the lower mantle. These predicted values are in excellent agreement with geodynamic analyses, in which the ratios ( ln / lnV
S
)
P
and ( / lnV
S
)
P
are free parameters arbitrarily adjusted to fit the tomography and geoid data. 相似文献