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81.
Vladimir Sokolov Takashi Furumura Friedemann Wenzel 《Bulletin of Earthquake Engineering》2010,8(4):767-786
The estimation of strength of shaking at a site from the initial P-wave portion of ground motion is the key problems for shortening
the alert time of the earthquake Early Warning (EEW). The most of the techniques proposed for the purpose utilize (a) ground
motion models based on the estimated magnitude and hypocentral distance, or (b) the interim proxies, such as initial vertical
displacement P
d
. We suggest the instrumental Japan Meteorological Agency (JMA) intensity (JMAI) as a characteristic for fast estimation of damage potential in the EEW systems. We investigated the scaling relations between
JMAI measured using the whole earthquake recordings (overall intensity) and using particular time intervals of various duration
(2.0–8.0 s) starting from the P-wave arrival (preliminary intensity). The dataset included 3,660 records (K-NET and the KiK-net
networks) from 55 events (M
W 4.1–7.4) occurred in 1999–2008 in Japan. We showed that the time interval of 4–5 s from the P-wave arrival can be used for
reliable estimations of the overall intensity with the average standard error of about 0.5 JMA units. The uncertainty in the
prediction may be reduced by consideration of local site conditions or by development of the station-specific models. 相似文献
82.
Koji Kiyosugi Yoshiyuki Horikawa Takashi Nagao Tetsumaru Itaya Charles B. Connor Kazuhiro Tanaka 《Bulletin of Volcanology》2014,76(1):1-14
Scoria cones are common volcanic features and are thought to most commonly develop through the deposition of ballistics produced by gentle Strombolian eruptions and the outward sliding of talus. However, some historic scoria cones have been observed to form with phases of more energetic violent Strombolian eruptions (e.g., the 1943–1952 eruption of Parícutin, central Mexico; the 1975 eruption of Tolbachik, Kamchatka), maintaining volcanic plumes several kilometers in height, sometimes simultaneous with active effusive lava flows. Geologic evidence shows that violent Strombolian eruptions during cone formation may be more common than is generally perceived, and therefore it is important to obtain additional insights about such eruptions to better assess volcanic hazards. We studied Irao Volcano, the largest basaltic monogenetic volcano in the Abu Monogenetic Volcano Group, SW Japan. The geologic features of this volcano are consistent with a violent Strombolian eruption, including voluminous ash and fine lapilli beds (on order of 10?1 km3 DRE) with simultaneous scoria cone formation and lava effusion from the base of the cone. The characteristics of the volcanic products suggest that the rate of magma ascent decreased gradually throughout the eruption and that less explosive Strombolian eruptions increased in frequency during the later stages of activity. During the eruption sequence, the chemical composition of the magma became more differentiated. A new K–Ar age determination for phlogopite crystallized within basalt dates the formation of Irao Volcano at 0.4?±?0.05 Ma. 相似文献
83.
Effects of bottom bracings on torsional dynamic characteristics of horizontally curved twin I-girder bridges with different curvatures 总被引:1,自引:0,他引:1
Curved twin I-girder bridges (CTIGBs) have low torsional stiffness that makes them vulnerable to dynamic loads.This study investigates the effects of bottom bracings on the torsional dynamic characteri... 相似文献
84.
Tomoki Sato Takashi Miyazaki Yoshihiko Tamura James B. Gill Martin Jutzeler Ryoko Senda Jun‐Ichi Kimura 《Island Arc》2020,29(1)
The International Ocean Discovery Program Expedition 350 drilled between two Izu rear‐arc seamount chains at Site U1437 and recovered the first complete succession of rear‐arc rocks. The drilling reached 1806.5 m below seafloor. In situ hyaloclastites, which had erupted before the rear‐arc seamounts came into existence at this site, were recovered in the deepest part of the hole (~15–16 Ma). Here it is found that the composition of the oldest rocks recovered does not have rear‐arc seamount chain geochemical signatures, but instead shows affinities with volcanic front or some of the extensional zone basalts between the present volcanic front and the rear‐arc seamount chains. It is suggested that following the opening of the Shikoku back‐arc Basin, Site U1437 was a volcanic front or a rifting zone just behind the volcanic front, and was followed at ~ 9 Ma by the start of rear‐arc seamount chains volcanism. This geochemical change records variations in the subduction components with time, which might have followed eastward moving of hot fingers in the mantle wedge and deepening of the subducting slab below Site U1437 after the cessation of Shikoku back‐arc Basin opening. 相似文献
85.
This study is intended to evaluate the influence of dynamic bridge-train interaction (BTI) on the seismic response of the
Shinkansen system in Japan under moderate earthquakes. An analytical approach to simulate the seismic response of the BTI
system is developed. In this approach, the behavior of the bridge structure is assumed to be within the elastic range under
moderate ground motions. A bullet train car model idealized as a sprung-mass system is established. The viaduct is modeled
with 3D finite elements. The BTI analysis algorithm is verified by comparing the analytical and experimental results. The
seismic analysis is validated through comparison with a general program. Then, the seismic responses of the BTI system are
simulated and evaluated. Some useful conclusions are drawn, indicating the importance of a proper consideration of the dynamic
BTI in seismic design. 相似文献
86.
To determine the existence of p-nitrophenol (PNP)-lowering bacteria in intestine of Japanese coastal fish, the gastro-intestinal contents were incubated in Brain Heart Infusion (BHI) broth and minimal medium (MM) broths containing 1 mmol/L PNP at 30 °C for 7 days. Among 26 samples of 19 fish species, 17 samples showed a decrease in PNP of 0.5-0.8 mmol/L in BHI broth, but no decrease was shown in MM broth. Eighteen PNP-lowering bacterial strains were isolated from four fishes. All of the strains were identified as Lactococcus lactis subsp. lactis. Three L. lactis strains JS1-3 isolated from Japanese seabass Lateolabrax japonicus showed the highest PNP-lowering activity (0.44 mmol/L). Optimum temperature and pH for the growth and PNP decreasing corresponded with the marine environment. These results suggested that marine fishes have PNP decreasing bacteria in their intestine. These bacteria might protect host fish from toxicities of PNP and PNP related compounds. 相似文献
87.
88.
Taku Tada Yoshinobu Tsuji Masahito Tsukamoto Yoshikazu Ueno Masayuki Kawashima Takashi Egawa Yasuhiro Yamazaki 《Pure and Applied Geophysics》1992,138(2):309-322
We carried out observations of sea-level fluctuations simultaneously at three stations on the coast of Heda Bay, Honshu, Japan, using supersonic-type water level gauges controlled by a personal computer. Analyses of the obtained data showed predominant spectral peaks at periods of 7.6, 2.0 and 1.3 minutes for all three stations. Comparison of the observed data with numerically calculated normal oscillation modes of the bay indicates that these three spectral peaks correspond to the theoretical first, third and seventh normal modes of the basin respectively, judging from the results of cross-spectral analyses. The reason for the absence of the remaining normal modes, especially of the second or the lateral first mode of the basin, is briefly considered. 相似文献
89.
Street and garden trees in urban areas are often exposed to advection of strong vapour pressure deficit (VPD) air that can raise the whole‐tree transpiration rate (ET), known as the oasis effect. However, urban trees tend to have small soil volume compared with natural conditions, and so they are believed to strongly regulate stomata. ET characteristics of such urban trees have not been well understood because of a lack of reliable measurement methods. Therefore, we propose a novel weighing lysimeter method and investigate the whole‐tree water balance of an isolated container‐grown Zelkova serrata to examine (a) which biotic and abiotic factors determine ET and (b) which spatial and temporal information is needed to predict ET under urban conditions. Whole‐tree water balance and environmental conditions were measured from 2010 to 2012. Although leaf area substantially increased in the study period, daily ET did not vary much. ET increased with VPD almost linearly in 2010 but showed saturation in 2011 and 2012. Root water uptake lagged ET by 40 min in 2012. These results suggest that the small planter box interfered with root growth and that hydraulic supply capacities did not increase sufficiently to support leaf area increase. From analysis of water balance, we believe that neglecting soil drought effects on street trees without irrigation in Japan will overestimate ET over 4–5 sunny days at the longest. This is unlike previous studies of forest. 相似文献
90.