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101.
A method of body-wave inversion is developed in an attempt to extract the information about asperities or barriers in a fault zone. A sequence of point sources, each being characterized with the seismic moment, the onset time and the location, are iteratively derived from observed records at multi-stations, where the two-dimensional extent of the source location is taken into account. A modification is made of the iterative method of Kikuchi and Kanamori on the formulation of inversion procedure to facilitate the computation.Using this method, we analyse long period P waves of the Tokachi-Oki earthquake of 1968 (Mw = 8.2) and obtain several significant subevents with time durations of ~ 10 s. Their spatio-temporal distribution shows that the rupture process consists of three characteristic stages: (A) a stage of introductory rupture, (B) a stage of main rupture and (C) a stage of aftershocks. The main rupture takes place in the form of clustering around a few sites of the fault plane. The largest subevent occurs in the northwestern corner. The stress drop associated with this event is estimated to be ~ 200 bars, one order of magnitude higher than the stress drop averaged over the entire fault plane. The sum of the seismic moments of the individual subevents amounts to 2.3 × 1028 dyn. cm which approximately coincides with the one estimated from the analysis of long-period surface waves. This implies that the source of the Tokachi-Oki earthquake consists of several major subevents with time durations of ~ 10 s in addition to other minor subevents. 相似文献
102.
The interaction of the isotropic stellar wind with the rotating isothermal cloud surrounding the young star is investigated. The density distribution of the cloud is taken as that for the equilibrium state of the rotating isothermal cloud modified by adding the rarefied interstellar gas in the polar region. The development of the shock envelope and the structure of the shell induced by the stellar wind are obtained. It is shown that the envelope of the shock front elongates and opens to the polar direction with half opening angle of about 20 degrees resulting the bipolar flow which is able to reproduce well the observed properties for the outflow in the bipolar sources. 相似文献
103.
Assessing the impacts of climate change on rice yields in the main rice areas of China 总被引:8,自引:1,他引:8
Fengmei Yao Yinglong Xu Erda Lin Masayuki Yokozawa Jiahua Zhang 《Climatic change》2007,80(3-4):395-409
This paper assesses the impact of climate change on irrigated rice yield using B2 climate change scenario from the Regional
Climate Model (RCM) and CERES-rice model during 2071--2090. Eight typical rice stations ranging in latitude, longitude, and
elevation that are located in the main rice ecological zones of China are selected for impact assessment. First, Crop Estimation
through Resource and Environment Synthesis (CERES)-rice model is validated using farm experiment data in selected stations.
The simulated results represent satisfactorily the trend of flowering duration and yields. The deviation of simulation within
± 10% of observed flowering duration and ± 15% of observed yield. Second, the errors of the outputs of RCM due to the difference
of topography between station point and grid point is corrected. The corrected output of the RCM used for simulating rice
flowering duration and yield is more reliable than the not corrected. Without CO2 direct effect on crop, the results from the assessment explore that B2 climate change scenario would have a negative impact
on rice yield at most rice stations and have little impacts at Fuzhou and Kunming. To find the change of inter-annual rice
yield, a preliminary assessment is made based on comparative cumulative probability at low and high yield and the coefficient
variable of yield between the B2 scenario and baseline. Without the CO2 direct effect on rice yield, the result indicates that frequency for low yield would increase and it reverses for high yield,
and the variance for rice yield would increase. It is concluded that high frequency at low yield and high variances of rice
yield could pose a threat to rice yield at most selected stations in the main rice areas of China. With the CO2 direct effect on rice yield, rice yield increase in all selected stations. 相似文献
104.
Acta Geotechnica - Gas production by depressurization can significantly increase the effective stress in hydrate-bearing sediments. Therefore, strength and deformation characteristics of sediments... 相似文献
105.
Shin Oya Hiroshi Terada Yutaka Hayano Makoto Watanabe Masayuki Hattori Yosuke Minowa 《Experimental Astronomy》2016,42(1):85-98
Stellar images have been obtained under natural seeing at visible and near-infrared wavelengths simultaneously through the Subaru Telescope at Mauna Kea. The image quality is evaluated by the full-width at the half-maximum (FWHM) of the stellar images. The observed ratio of FWHM in the V-band to the K-band is 1.54 ± 0.17 on average. The ratio shows tendency to decrease toward bad seeing as expected from the outer scale influence, though the number of the samples is still limited. The ratio is important for simulations to evaluate the performance of a ground-layer adaptive optics system at near-infrared wavelengths based on optical seeing statistics. The observed optical seeing is also compared with outside seeing to estimate the dome seeing of the Subaru Telescope. 相似文献
106.
Distribution,age, and origin of a submarine landslide deposit in the Pleistocene Kiwada Formation,forearc basin fill on the Boso Peninsula,east‐central Japan: Constraints from tephro‐ and biostratigraphy 下载免费PDF全文
Masayuki Utsunomiya 《Island Arc》2018,27(4)
A mass‐transport deposit named MTD1 (up to 100 m in thickness) is intercalated in the upper Kiwada Formation, a Pleistocene forearc basin fill on the Boso Peninsula, east‐central Japan. The present study aims to examine the origin, age, and distribution of MTD1. MTD1 consists mainly of mudstone blocks containing thin very fine‐ to medium‐grained sandstones, and ranges from tens of centimeters to more than tens of meters in length and thickness. Correlation of marker tuff beds and application of the biostratigraphy of calcareous nannofossils suggest that the blocks in MTD1 were derived from the underlying strata. The total thickness of the stratified blocks from the different stratigraphic horizons exceeds 60 m, implying that MTD1 originated from deeply‐excavated slope failure. The slope failure occurred in a short time interval at ca 1.3 Ma. MTD1 provides an estimate of the height of the escarpment on the basis of the stratigraphic origin of the blocks. 相似文献
107.
Masayuki Uesugi Motoo Ito Hikaru Yabuta Hiroshi Naraoka Fumio Kitajima Yoshinori Takano Hajime Mita Yoko Kebukawa Aiko Nakato Yuzuru Karouji 《Meteoritics & planetary science》2019,54(3):638-666
Carbonaceous materials in the sample catcher of the Hayabusa spacecraft were assigned as category 3 particles. We investigated the category 3 particles with a suite of in situ microanalytical methods. Possible contaminants collected from the cleanrooms of the spacecraft assembly and extraterrestrial sample curation center (ESCuC) were also analyzed in the same manner as category 3 particles for comparison. Our data were integrated with those of the preliminary examination team for category 3 particles. Possible origins for the category 3 particles include contamination before and after the operation of the Hayabusa spacecraft. 相似文献
108.
The mechanism of the Q-burst is investigated in the time and frequency domains. Electric fields in the ELF (extremely low frequency) to VLF (very low frequency) range have been observed with a ball antenna since 2003 in Kochi City, Japan (latitude 33.3°north, longitude 133.4°east). Source-to-observer distances (SODs) of Q-bursts are estimated by analyzing the waveforms. It is found as a result that the Q-burst is produced by combination of direct and antipodal pulses from a source lightning stroke occurring all over the world. 相似文献
109.
Caroline van Breukelen Chris Simpson Steve Rawlings Masayuki Akiyama David Bonfield Lee Clewley Matt J. Jarvis Tom Mauch Tony Readhead Ann-Marie Stobbart Mark Swinbank Mike Watson 《Monthly notices of the Royal Astronomical Society》2009,395(1):11-27
We discuss the optical properties, X-ray detections and active galactic nucleus (AGN) populations of four clusters at z ∼ 1 in the Subaru–XMM Deep Field (SXDF). The velocity distribution and plausible extended X-ray detections are examined, as well as the number of X-ray point sources and radio sources associated with the clusters. We find that the two clusters that appear virialized and have an extended X-ray detection contain few, if any, AGN, whereas the two pre-virialized clusters have a large AGN population. This constitutes evidence that the AGN fraction in clusters is linked to the clusters' evolutionary stage. The number of X-ray AGN in the pre-virialized clusters is consistent with an overdensity of a factor of ∼200; the radio AGN appear to be clustered with a factor of 3 to 6 higher. The median K -band luminosities of LK = 1.7 ± 0.7 L * for the X-ray sources and LK = 2.3 ± 0.1 L * for the radio sources support the theory that these AGN are triggered by galaxy interaction and merging events in sub-groups with low internal velocity distributions, which make up the cluster environment in a pre-virialization evolutionary stage. 相似文献
110.
Seismological evidence for compositional variations at the base of the mantle transition zone under Japan Islands 总被引:1,自引:1,他引:0
Akira Yamada Dapeng Zhao Toru Inoue Daisuke Suetsugu Masayuki Obayashi 《Gondwana Research》2009,16(3-4):482-490
Temperature and water content anomalies just above the 660-km discontinuity under the Japan Islands are estimated from seismological observations. Two sets of seismological observations of P-wave velocity perturbations and depth variations of the 660-km discontinuity are used, which are (1) long-wavelength (~ 500 km) variations from seismic tomography based on a grid parameterization and waveform analysis of ScS reverberations and (2) moderate-wavelength (~ 150 km) variations from seismic tomography with a block parameterization and receiver-function analysis. To estimate temperature and water content anomalies, partial derivatives of velocity and depth variations with respect to temperature and water content determined by mineral physics studies are used. Under Southwest Japan, low temperature and high water-content anomalies are obtained from both sets of seismological observations, which have already been found by a previous study. Under Northeast Japan, however, there are discrepancies between the results estimated from the two data sets, possibly due to the different resolution scales. This discrepancy is dismissed when examining distributions of the temperature and water content anomalies. These anomalies can be grouped into two geographical locations, one group under Southwest Japan, the other under Northeast Japan. The two groups are clearly separated and exhibit common features in both sets of the seismological observations. The grouping is interpreted by a compositional difference between the subducting Pacific slab under Southwest Japan and a normal mantle under Northeast Japan. 相似文献