2017-09 http://hdl.handle.net/11605/100 2026-03-25T06:48:08Z 2026-03-25T06:48:08Z 村越, 匠 西澤, 航 岩瀨, 康行 江口, 孝雄 http://hdl.handle.net/11605/104 2017-10-27T05:52:05Z 2017-08-31T15:00:00Z

タイトル: MeSO-net を用いたバックプロジェクション法による関東地方の中規模地震の破壊過程の解析 著者名: 村越, 匠; 西澤, 航; 岩瀨, 康行; 江口, 孝雄 抄録: The current study aims to obtain the rupture process of moderate-size earthquakes in space and time by using waveforms in the Metropolitan Seismic Observation Network (MeSO-net). The MeSO-net, in which all stations were established in 2012, is high-density seismograph network in and around the Tokyo metropolitan area, Japan. The average station-to-station distances in MeSO-net are several kilometers. The average intervals are less than a quarter of existing seismic networks in Japan, where the average distances in K-net and KiK-net are about 20 km. Then, we analyze the fault motion of moderate-size earthquakes in and around Kanto area, Japan by applying the back-projection method to seismic waveforms in MeSO-net. We construct detail images of the rupture process of moderate-size earthquakes. As a result, the spatial resolution of the rupture process for M5.1 earthquake is 0.5 km.

2017-08-31T15:00:00Z 川上, 貴士 板野, 稔久 http://hdl.handle.net/11605/103 2017-10-27T05:20:09Z 2017-08-31T15:00:00Z

タイトル: 結晶形状に準拠した座標系による氷晶成長の2 次元数値シミュレーション 著者名: 川上, 貴士; 板野, 稔久 抄録: Ice crystal growth by diffusion of water vapor from supercooled liquid water is simulated with equations written in a surface-following coordinate system. This two-dimensional system, similar to “terrain-following coordinate system” used in meteorology and oceanography, consists of the one axis pointing vertical and the other following the crystal geometry. It facilitates the introduction of the boundary condition on the surface of ice crystal so that simplifies the algorithm for computer programming. By introducing the system, the growth of one branch of snow crystal is simulated smoothly in contrast to the previous simulations adopting the ordinary rectangular coordinate system where it becomes bumpy. Also, while the rectangular coordinate system shows different growth rate and shape of ice crystal with grid resolution, those obtained from the surface-following coordinate system depend little on grid resolution.

2017-08-31T15:00:00Z 岩瀨, 康行 http://hdl.handle.net/11605/102 2017-10-27T05:19:01Z 2017-08-31T15:00:00Z

タイトル: Olami-Feder-Christensen モデルによる浅発地震の再現へ向けて 著者名: 岩瀨, 康行 抄録: Incorporating possible mechanisms in actual faults into the Olami-Feder-Christensen earthquake model (OFC model), we verified the results from the viewpoint of self-organizing critical phenomena. In the model considering size, shape and static heterogeneity of the fault, the power law of the power index -1.2 is found for the energy (or scale) and the number of occurrences of the "earthquake", indicating that these results was not inherently affected by the parameter. However, considering attenuation and dynamic inhomogeneity, the absolute value of the exponent became large, but the power law was still observed. These results suggest that earthquakes based on the OFC model essentially represent self-organized critical phenomena. There were some cases where the statistical distribution of the temporal change of the earthquake energy could be approximated by the q-Gaussian distribution. Further research is required to clarify the criticality of the earthquakes in OFC model.

2017-08-31T15:00:00Z 大石, 碧 渡邉, 恭子 釜谷, 秀幸 http://hdl.handle.net/11605/101 2017-10-27T05:17:02Z 2017-08-31T15:00:00Z

タイトル: 低質量星に対するCME のUV 放射量供給による生命存在領域の拡大 著者名: 大石, 碧; 渡邉, 恭子; 釜谷, 秀幸 抄録: It is very important to consider the amount of UV (ultra-violet) radiation for life existence and evolution because moderate UV radiation is necessary for the synthesis of biological compounds. Recently, life on the low mass stars has been suggested because of their long lifespan. However, these stars are out of ‘‘common region’’ between HZ (habitable zone) and UV-HZ, where the persistent life existence is expected because of lack of UV radiation. Then, this paper considers UV-HZ with the intensive supply of UV radiation from Coronal Mass Ejection (CME) and explores to increase the range of the common region around low mass stars. Then, we find the common region doesn’t always spread so much because CME size is proportion to the distance from a host star and the peak of UV luminosity depends on evolutionary phase of main sequence stars.

2017-08-31T15:00:00Z