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71.
Osamu Fujiwara Kazuomi Hirakawa Toshiaki Irizuki Shiro Hasegawa Yoshitaka Hase Jun‐ichi Uchida Kohei Abe 《Island Arc》2010,19(3):374-388
A flight of Holocene marine terraces on the southwestern coast of Cape Omaezaki of central Japan provides evidence of recurrent millennium‐scale uplift events. We reconstructed the uplift history of these terraces by using facies analysis of drill core and geoslicer samples, environmental analysis of trace fossils, and 14C age determinations. Coastal uplift can be identified by the displacement of beach deposits such as foreshore deposits, which represent the intertidal swash zone of a wave‐dominated sandy coast. Three levels of former beach deposits facing the Nankai Trough were identified near the coast in the Omaezaki area. The highest of these, dated at about 3020–2880 BC, records a maximum of 2.2–2.7 m of emergence. The middle beach surface, of minimum age 370–190 BC, shows 1.6–2.8 m of emergence. The lowest beach surface, which is older than 1300–1370 AD, records 0.4–1.6 m of emergence. Our analysis of vertical crustal deformation data during the Holocene in this region suggests that rapid and strong uplift was restricted to the southwestern coast of the Omaezaki area and was probably caused by high‐angle thrusting on subsidiary faults branching from the underlying plate boundary megathrust. 相似文献
72.
73.
Influence of interaction between small asperities on various types of slow earthquakes in a 3-D simulation for a subduction plate boundary 总被引:3,自引:1,他引:2
Keisuke Ariyoshi Takane Hori Jean-Paul Ampuero Yoshiyuki Kaneda Toru Matsuzawa Ryota Hino Akira Hasegawa 《Gondwana Research》2009,16(3-4):534-544
Recently, the occurrence of slow earthquakes such as low-frequency earthquakes and very low-frequency earthquakes have been recognized at depths of about 30 km in southwest Japan and Cascadia. These slow earthquakes occur sometimes in isolation and sometimes break into chain-reaction, producing tremor that migrates at a speed of about 5–15 km/day and suggesting a strong interaction among nearby small asperities. In this study, we formulate a 3-D subduction plate boundary model with two types of small asperities chained along the trench at the depth of 30 km. Our simulation succeeds in representing various types of slow earthquakes including low-frequency earthquakes and rapid slip velocity in the same asperity, and indicates that interaction between asperities may cause the very low-frequency earthquakes. Our simulation also shows chain reaction along trench with propagation speed that can be made consistent with observations by adjusting model parameters, which suggests that the interactions also explain the observed migration of slow earthquakes. 相似文献
74.
75.
Extinction coefficients were measured for three kind of hydrous silicate minerals, montmorillonite, chlorite and serpentine, from 7 to 140 m. The infrared extinction coefficients of these minerals show (1) a few broad bands in the mid-infrared region and (2) a less steep wavelength-dependence in the far-infrared region, in contrast to those of high-temperature magnesium silicates. In the far-infrared region, montmorillonite shows a –0.8±0.1 dependence (, the wavelength) without any band structure, chlorite has a double maxima structure around 80 m, and serpentine shows a rather steep dependence with a small peak at 77 m.The changes of mid-infrared spectra by heating were measured. Change in chlorite spectrum is the most significant. Many fine features appear by heating and then they disappear. Above 900°C one broad feature remains around 10 m. Fine features of the montmorillonite spectrum disappear by heating. For serpentine, many new peaks appear and the spectrum resembles the spectrum of olivin. In near-infrared a band around 2.72 m disappears by heating.Extinction coefficients at very low temperatures were measured in the far-infrared region. For montmorillonite and serpentine, the spectrum is the same as that at room temperature. The double peaks of chlorite around 80 m become higher. 相似文献
76.
Jun Fan Tian-Chang Chen Wei-Bin Han Jian Zeng Si-Hua Zheng Akira Hasegawa Shigeki Horiuchi 《地震学报(英文版)》1998,11(3):375-379
Conclusions The real-time processing system of CTSN performs following: A/D conversion; automatic event detection; event data saving;
automatic measure of P and S arrivals; event location and print out the calculated results. It is corrected at ny moment by
using the off-line system. Since December 1993, this system has been operating normally in the CTSN. More than 4 000 earthquakes
have been recorded in the system. It has high accuracy in automatic picking P and S arrivals. The location of the earthquakes
determined by on-line system are close to those given in published catalogues which are determined by manual procedure. This
system can finish locate event in three minutes. It also gives satisfactory epicenter locations for distant events by inputting
manually S arrivals in the off-line system. The operation of this system had brought the technical superiority of the CTSN.
It not only reduces the labor intensity and simplifies the working procedure, but also makes our research facility into the
superior ranks in this field of our country.
In conclusion, the real-time processing system of seismic wave provides technical support for the daily requirements of monitoring
seismic activity as well as a lot of digital waveform data used seismic research in Sichuan area.
This subject is sponsored by the Scientific and Technical Committee of Sichuan Province. 相似文献
77.
Akira Hasegawa 《Solar physics》1976,47(1):325-330
Most of the MHD instabilities originating from the nonuniformity of a plasma excite MHD surface wave. When the excited wave has a frequency s which corresponds to the local shear Alfvén wave resonance (s = k
v
a
(x), where v
a
is the Alfvén speed and k
is the wave number in the direction of the magnetic field), the surface wave resonantly mode converts to the kinetic Alfvén wave, the Alfvén wave having a perpendicular wavelength comparable to the ion gyroradius and being able to propagate across the magnetic field. We discuss various linear and nonlinear effects of this kinetic Alfvén wave on the plasma including particle acceleration and heating. A specific example for the case of a MHD Kelvin-Helmholtz instability is given. 相似文献
78.
Mid-infrared extinction coefficients of five natural amorphous silicates and seven synthetic glasses were measured. Three bands at about 10, 12, and 20 μm were seen for all the measured samples. The quantities of these bands are found to have good correlations with the SiO2 content of the samples. The correlations are the most remarkable for the 10 μm band. As the SiO2 content decreases, the peak wavelengthλ m shifts to longer side, the peak heightK m decreases and the full width of half maximumW increases. A quantityλ m K m W is constant within 15%. Empirical formula $$\lambda_m (\mu m) = {11.10-2.30 x 10^-2} {[SiO_2 wt.\%]} \pm 0.15$$ and $$W(\mu m) = {5.14-4.68 x 10^- 2} {[SiO_2 wt.\%]} \pm 0.30$$ are obtained for the measured samples. Therefore, the correlation is present between the 10 μm peak wavelengthλ m and peak widthW for amorphous silicates. The change in peak widthW is remarkable compared the change in peak wavelengthλ m as the SiO2 content varies. For the 12 μm band the correlations with the SiO2 content are not so good. A tendency that theλ m shifts to the red and theK m lowers as the decreasing SiO2 content are found. For the samples with SiO2 content less than 50% the 12 μm band cannot recognized as the peak. For the 20 μm band, theλ m is almost independent on SiO2 content and theK m lowers with decreasing SiO2 content. The results are compared with the observed 10 μm band of the astronomical objects. A method to estimate the SiO2 content of astronomical grain materials is proposed and 48±8% SiO2 wt.% is found corresponding to the peak wavelength of 9.7 μm and the peak width of 2.5–3.0 μm of typical celestial objects. 相似文献
79.
Ikawa Hiroki Kuwagata Tsuneo Haginoya Shigenori Ishigooka Yasushi Ono Keisuke Maruyama Atsushi Sakai Hidemitsu Fukuoka Minehiko Yoshimoto Mayumi Ishida Sachinobu Chen Charles P. Hasegawa Toshihiro Watanabe Tsutomu 《Boundary-Layer Meteorology》2021,179(3):447-476
Boundary-Layer Meteorology - Known as the heat-mitigation effect, irrigated rice-paddy fields distribute a large fraction of their received energy to the latent heat during the growing season. The... 相似文献
80.
We present high resolution CS and CO maps of Cep A region made with the 45m telescope at Nobeyama. The CS map shows that a dense cloud surrounding the proto-star cluster extends in the North-South direction and is probably rotating. The bipolar molecular flow apparent in the CO maps is well-collimated along East-West direction within 0.2 pc from the proto-stars. The dense cloud is gravitationally unstable and appears to be in a contracting phase to form a cluster of massive stars.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.NRO, a branch of the Tokyo Astronomical Observatory, University of Tokyo, is a cosmic radio observing facility open for outside users. 相似文献