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Artificially triggered lightning and its characteristic discharge parameters in two severe thunderstorms 总被引：2，自引：0，他引：2
Qie XiuShu Zhang QiLin Zhou YunJun Feng GuiLi Zhang TingLong Yang Jing Kong XiangZhen Xiao QingFu Wu ShuJun 《中国科学D辑(英文版)》2007,50(8):1241-1250
The lightning-induced-damages in the mid-latitude regions are usually caused during severe thunder-storms. But the discharge parameters of natural lightning are difficult to be measured. Five lightning flashes have been artificially triggered with the rocket-wire technique during the passage of two severe thunderstorms. The discharge current and close electric field of return stroke in artificially triggered lightning have been obtained in microsecond time resolution by using current measuring systems and electric field change sensors. The results show that the five triggered lightning flashes include 1 to 10 return strokes, and the average return stroke current is 11.9 kA with a maximum of 21.0 kA and a mini-mum of 6.6 kA, similar to the subsequent return strokes in natural lightning. The half peak width of the current waveform is 39 μs, which is much larger than the usual result. The peak current of stroke Ip (kA) and the neutralized charge Q(C) has a relationship of Ip = 18.5Q0.65. The radiation field of return stroke is 5.9 kV·m-1 and 0.39 kV·m-1 at 60 m and 550 m, respectively. The radiation field decreases as r -1.119 with increase of horizontal distance r from the discharge channel. Based on the well-accepted transmission line model, the speed of return stroke is estimated to be about 1.4×108 m·s-1, with a variation range of (1.1―1.6)×108 m·s-1. Because of the similarities of the triggered lightning and natural lightning, the results in this article can be used in the protection design of natural lightning. 相似文献
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Uri Schattner 《Earth and Planetary Science Letters》2010,289(3-4):539-548
Subduction plays a fundamental role in plate tectonics and when interrupted it may trigger a series of geodynamic and sedimentary responses. Synchronous structural modifications recorded across the entire eastern Mediterranean region are dated to a relatively short period — early-to-mid Pleistocene. These deformations are documented within plates (e.g., Arabian, Sinai and African plates), along plate boundaries (e.g., Dead Sea and North Anatolian faults and Cyprus Arc), and in the Mediterranean basin. During the same period the northward subduction of the Sinai plate was interrupted when the Eratosthenes Seamount–Cyprus Arc collision initiated. Subduction–collision processes of the eastern Mediterranean serve as a unique modern analogue for similar settings worldwide. Understanding their association with accompanying neo-tectonic processes is therefore predominantly important. By fostering a detailed and comprehensive approach this research provides a coherent tectonic picture for the eastern Mediterranean early-to-mid Pleistocene tectonic transition in order to explore its triggering mechanisms. Since the Neogene convergence across the eastern Mediterranean was accompanied by Eurasian indentation by Arabia northward motion, westwards Anatolia escape and southwards Aegean propagation. This semi counterclockwise plate motion was temporarily interrupted by the incipient Seamount–Arc collision which is suggested here as a trigger of the early-to-mid Pleistocene tectonic transition. 相似文献
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《地震科学（英文版）》2010,(6)
Some recent publications presented a result suggesting that Zipingpu reservoir hastened the occurrence of the 2008 MS8.0 Wenchuan earthquake by tens to hundreds of years.Their researches calculated the Coulomb stress change induced by Zipingpu reservoir on the rupturing fault of Wenchuan earthquake.Their results,however,are critically dependent upon the 3-D event location,reservoir location,and the fault plane orientation.We repeated Ge et al.'s work in this paper and found that an improper dip angle parameter of their 2-D fault model might lead to a wrong conclusion.Both the modeling results based on the 2-D model and 3-D model with proper fault parameters will show Coulomb stress changes alone were neither large enough nor had the correct orientation to affect the occurrence of Wenchuan earthquake,which supports our recent argument based on the local seismicity analysis and the induced Coulomb stress change calculation with a 3-D model. 相似文献
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Kenji Satake Alexander Rabinovich Utku Kano?lu Stefano Tinti 《Pure and Applied Geophysics》2011,168(6-7):963-968
Eighteen papers are included in Volume 1 of a PAGEOPH topical issue Tsunamis in the World Ocean: Past, Present, and Future. These papers are briefly introduced. They are grouped into three categories: case studies of earthquake-generated tsunamis; tsunami forecast and hazard assessments; and theoretical and computational modeling of tsunami generation, propagation, and coastal behavior. Most of the papers were presented at the 24th International Tsunami Symposium held 14?C16 July 2009 in Novosibirsk, Russia, and reflect the current state of tsunami science. 相似文献
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Nobuyuki Morikawa Shigeki Senna Yuzuru Hayakawa Hiroyuki Fujiwara 《Pure and Applied Geophysics》2011,168(3-4):645-657
The strong ground motion prediction method ??Recipe?? was published by the Headquarters for Earthquake Research Promotion (HERP) of Japan. HERP has applied this method to prepare shaking maps for scenario earthquakes in specific active faults. Recently, Recipe was updated following its verification by simulations of strong ground motions associated with the Mw?=?6.6 off-shore earthquake west of Fukuoka prefecture in 2005, which occurred in the northwest part of the Kego fault zone located in northern Kyushu, Japan. One of the prominent changes in the upgraded version of Recipe is the inclusion of a procedure to evaluate seismic intensities on the ground surface from waveforms of S-wave velocity of 400?m/s on the engineering bedrock. By applying the upgraded version of Recipe, we have made shaking-maps for earthquakes in the southeast part of the Kego fault zone, which is located directly below the mega-city of Fukuoka. We assume four source models for scenario earthquakes; the locations of the asperities and the hypocenters vary between the models. The results show that in all cases, disastrous seismic intensities can strike a wide area of Fukuoka city. Differences in the distributions of seismic intensities among the four cases can be clearly observed in the area located on the extension of the source fault. Furthermore, we construct a velocity-layer structure model on the engineering bedrock for the central area of Fukuoka city. We assess not only the distribution of seismic intensities but also waveforms on the ground by using an equivalent linear method for the central area of Fukuoka city. 相似文献
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J?rg-Olaf Wolff 《Ocean Dynamics》2011,61(5):559-561
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Md. Sharwar Murshed Sangil Kim Jeong-Soo Park 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(7):897-911
The beta-κ distribution is a distinct case of the generalized beta distribution of the second kind. In previous studies, beta-p and beta-κ distributions have played important roles in representing extreme events, and thus, the present paper uses the
beta-κ distribution. Further, this paper uses the method of moments and the method of L-moments to estimate the parameters
from the beta-κ distribution, and to demonstrate the performance of the proposed model, the paper presents a simulation study
using three estimation methods (including the maximum likelihood estimation method) and beta-κ and non beta-κ samples. In
addition, this paper evaluates the performance of the beta-κ distribution by employing two widely used extreme value distributions
(i.e., the GEV and Gumbel distributions) and two sets of actual data on extreme events. 相似文献
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Robert Kirby 《Ocean Dynamics》2011,61(2-3):233-244
Modern trends, increases in ship size, improved cargo handling capability, sea level rise and erosion threats to low-lying land, undesirable attributes of certain traditional mud dredging and disposal practices, coupled with pressure from environmental legislation, are all driving a need to manage coastal waters and fine sediment in a more sophisticated manner. Wide-ranging review of world ??best practice?? has highlighted five fully evolved northwest European generic sediment management systems (SMS) to address these challenges. These are being applied to universally recurring types of port facilities: impounded docks, lock entrances, semi-enclosed basins, channels and fairways. They are applicable to large and small, existing and new facilities in rivers, estuaries, open sea coasts, even in some cases to lakes. They can be passive or active. The functioning of each of these five is explained with comment on economic benefit. What emerges strongly is that the applied academic disciplines of physical and chemical oceanography, plus marine microbiology, are being drawn together to supplement or replace traditional maritime engineering. Following on from a Permanent International Association of Navigation Congresses review, these technologies are spreading beyond the northwest European conception area, as well as beginning to be adopted by international dredging companies. The complexity, scale of potential benefit, numbers of poorly understood issues highlighted and embryonic way these are beginning to spread all suggest that this is potentially an important area for future scientific endeavour. 相似文献
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E. Bertrand A.-M. Duval J. R��gnier R. M. Azzara F. Bergamashi P. Bordoni F. Cara G. Cultrera G. Di Giulio G. Milana J. Salichon 《Bulletin of Earthquake Engineering》2011,9(3):809-823
During the microzonation studies of the April 6th, 2009 L??Aquila earthquake, we observed local seismic amplifications in the Roio area??a plane separated from L??Aquila city center by mount Luco. Six portable, digital instruments were deployed across the plain from 15 April to mid-May 2009. This array recorded 152 aftershocks. We analyzed the ground motion from these events to determine relative site amplification within the plain and on surrounding ridges. Horizontal over vertical spectral ratio on noise data (HVSRN), aftershock recordings (HVEQ) and standard spectral ratio (SSR) showed amplifications at 1.3 and 4.0?Hz on quaternary deposits. Seismic amplifications in the frequency range of 4 and 6?Hz were also observed on a carbonate ridge of Colle di Roio, on the northwestern border of the plateau. A small amplification was noticed near the top of mount Luco, another rocky site. Large discrepancies in the amplification levels between methods have been observed for these sites, but the HVSRN, HVEQ and SSR gave similar results at the stations located in the Roio plain. On the rocky sites, the SSR was more reliable than the HVSRN at estimating the transfer function of the site, even if the resonance frequency seemed to be well detected by the latter method. 相似文献
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More damaging tsunamis have impacted Crescent City, California in historic times than any other location on the West Coast of the USA. Crescent City??s harbor has undergone significant modification since the early 20th century, including construction of several breakwaters, dredging, and a 200?×?300?m2 small boat basin. In 2006, a M w 8.3 earthquake in the Kuril Islands generated a moderate Pacific-wide tsunami. Crescent City recorded the highest amplitudes of any tide gauge in the Pacific and was the only location to experience structural damage. Strong currents damaged docks and boats within the small boat basin, causing more than US?$20 million in damage and replacement costs. We examine how modifications to Crescent City??s harbor may have affected its vulnerability to moderate tsunamis such as the 2006 event. A bathymetric grid of the basin was constructed based on US Army Corps of Engineers soundings in 1964 and 1965 before the construction of the small boat basin. The method of splitting tsunamis was used to estimate tsunami water heights and current velocities at several locations in the harbor using both the 1964?C1965 grid and the 2006 bathymetric grid for the 2006 Kuril event and a similar-sized source along the Sanriku coast of Japan. Model velocity outputs are compared for the two different bathymetries at the tide gauge location and at six additional computational sites in the harbor. The largest difference between the two grids is at the small boat basin entrance, where the 2006 bathymetry produces currents over three times the strength of the currents produced by the 1965 bathymetry. Peak currents from a Sanriku event are comparable to those produced by the 2006 event, and within the boat basin may have been higher. The modifications of the harbor, and in particular the addition of the small boat basin, appear to have contributed to the high current velocities and resulting damage in 2006 and help to explain why the 1933 M w 8.4?C8.7 Sanriku tsunami caused no damage at Crescent City. 相似文献
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G. Milana R. M. Azzara E. Bertrand P. Bordoni F. Cara R. Cogliano G. Cultrera G. Di Giulio A.M. Duval A. Fodarella S. Marcucci S. Pucillo J. R��gnier G. Riccio 《Bulletin of Earthquake Engineering》2011,9(3):741-759
After the 2009 April 6th Mw 6.3 L??Aquila earthquake (Central Italy) the Italian Civil Defense Department promoted the microzoning study in the ten zones in the epicentral area that suffered major damage. In this paper we present the activities and the results concerning a temporary seismic network installed in the historical L??Aquila city center indicated as ??macroarea 1?? in the microzoning project. Seismic data were collected to investigate the amplification effects in the city and to support the microzoning activities in verifying both geological profiles and 1D numerical modeling of the seismic response of the city. The conventional spectral approaches using both microtremor and earthquake data allowed to determine the fundamental resonance frequencies and the amplification factors within the city respectively. The spatial variability of these quantities can be related to the geological and geomorphologic characteristics of the investigated area. A comparison between the network data and the data recorded by the two strong motion instruments installed in the city was also made. This allows verifying the relative response of the accelerometric stations that recorded in the city the major events of the sequence. 相似文献
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Susan E. Hough Victor C. Tsai Robert Walker Fred Aminzadeh 《Journal of Seismology》2017,21(6):1613-1621
Several recent studies have presented evidence that significant induced earthquakes occurred in a number of oil-producing regions during the early and mid-twentieth century related to either production or wastewater injection. We consider whether the 21 July 1952 Mw 7.5 Kern County earthquake might have been induced by production in the Wheeler Ridge oil field. The mainshock, which was not preceded by any significant foreshocks, occurred 98 days after the initial production of oil in Eocene strata at depths reaching 3 km, within ~1 km of the White Wolf fault (WWF). Based on this spatial and temporal proximity, we explore a potential causal relationship between the earthquake and oil production. While production would have normally be expected to have reduced pore pressure, inhibiting failure on the WWF, we present an analytical model based on industry stratigraphic data and best estimates of parameters whereby an impermeable splay fault adjacent to the main WWF could plausibly have blocked direct pore pressure effects, allowing the poroelastic stress change associated with production to destabilize the WWF, promoting initial failure. This proof-of-concept model can also account for the 98-day delay between the onset of production and the earthquake. While the earthquake clearly released stored tectonic stress, any initial perturbation on or near a major fault system can trigger a larger rupture. Our proposed mechanism provides an explanation for why significant earthquakes are not commonly induced by production in proximity to major faults. 相似文献
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G. Di Giulio S. Marzorati F. Bergamaschi P. Bordoni F. Cara E. D��Alema C. Ladina M. Massa 《Bulletin of Earthquake Engineering》2011,9(3):783-807
The 2009 Mw 6.3 L’Aquila event caused extensive damage in the city of L’Aquila and in some small towns in its vicinity. The
most severe damage was recognized SE of L’Aquila town along the Aterno river valley. Although building vulnerability and near-source
effects are strongly responsible for the high level of destruction, site effects have been invoked to explain the damage heterogeneities
and the similarities between the 2009 macroseismic field with the intensities of historical earthquakes. The small village
of Onna is settled on quaternary alluvium and suffered during the L’Aquila event an extremely heavy damage in the masonry
structures with intensity IX–X on the Mercalli-Cancani-Sieberg (MCS) scale. The village of Monticchio, far less than 1.3 km
from Onna, is mostly situated on Mesozoic limestone and suffered a smaller level of damaging (VI MCS). In the present paper,
we analyze the aftershock recordings at seismic stations deployed in a small area of the middle-Aterno valley including Onna
and Monticchio. The aim is to investigate local amplification effects caused by the near-surface geology. Because the seismological
stations are close together, vulnerability and near-source effects are assumed to be constant. The waveform analysis shows
that the ground motion at Onna is systematically characterized by large high-frequency content. The frequency resonance is
varying from 2 to 3 Hz and it is related to alluvial sediments with a thickness of about 40 m that overlay a stiffer Pleistocene
substrate. The ground motion recordings of Onna are well reproduced by the predictive equation for the Italian territory. 相似文献