Effects of the 2011 Tohoku-oki tsunami and human activities on long-term coastal geomorphic development in northeastern Tohoku,Japan     

Haruki Imura  Kazuhisa Goto  Kenta Minamidate  Naoto Koiwa 《地球表面变化过程与地形》2024,49(2):949-963

The 2011 Tohoku-oki tsunami caused large-scale topographic changes along the Pacific coast of northeastern Japan. More than 10 years have passed since the tsunami waves struck the area. Today, because of reconstruction work, very few places exist where natural post-tsunami topographic changes can be monitored continuously. For this study, the authors investigated topographic changes caused not only by the 2011 tsunami but also by natural and artificial activities during the 50 years before and after the tsunami based on aerial photographs, excavations and subsurface explorations using ground-penetrating radar at the Osuka coast in Aomori prefecture, Japan. The site is rare because it is a protected area with few and superficial engineering activities, making it suitable for continuous observation of pre-tsunami, syn-tsunami and post-tsunami topographic changes. The findings indicate that the 2011 tsunami waves generated large topographic changes: depositional and erosional features produced by the tsunami can be recognized, respectively, as tsunami deposits and erosional channels across the sand dunes. During the post-tsunami phase, the sand volume at the coast quickly recovered naturally. Tsunami deposits and the erosional channels were well preserved underground even at 10 years after the event. However, dynamic movement of the dunes started after the tsunami. The shifting was attributable to the artificial clearing of coastal forests rather than the tsunami effects on the coast. Our results first indicate not only that the sedimentary features of paleo-tsunamis but also the erosional features have some probability of being preserved in the subsurface of the beach and sand dunes at tsunami-affected areas. Also, artificial activities such as deforestation are much more crucially undermining of the stability of the coastal geomorphology than the tsunami effects: the coast is now reaching a different status from its pre-tsunami situation.  相似文献   

Influence of the Atmospheric Model on Hanle Diagnostics     

Ryohko Ishikawa  Han Uitenbroek  Motoshi Goto  Yusuke Iida  Saku Tsuneta 《Solar physics》2018,293(5):74

We clarify the uncertainty in the inferred magnetic field vector via the Hanle diagnostics of the hydrogen Lyman-\(\upalpha\) line when the stratification of the underlying atmosphere is unknown. We calculate the anisotropy of the radiation field with plane-parallel semi-empirical models under the nonlocal thermal equilibrium condition and derive linear polarization signals for all possible parameters of magnetic field vectors based on an analytical solution of the atomic polarization and Hanle effect. We find that the semi-empirical models of the inter-network region (FAL-A) and network region (FAL-F) show similar degrees of anisotropy in the radiation field, and this similarity results in an acceptable inversion error (e.g., \({\sim}\, 40~\mbox{G}\) instead of 50 G in field strength and \({\sim}\,100^{\circ}\) instead of \(90^{\circ}\) in inclination) when FAL-A and FAL-F are swapped. However, the semi-empirical models of FAL-C (averaged quiet-Sun model including both inter-network and network regions) and FAL-P (plage regions) yield an atomic polarization that deviates from all other models, which makes it difficult to precisely determine the magnetic field vector if the correct atmospheric model is not known (e.g., the inversion error is much larger than 40% of the field strength; \({>}\,70~\mbox{G}\) instead of \(50~\mbox{G}\)). These results clearly demonstrate that the choice of model atmosphere is important for Hanle diagnostics. As is well known, one way to constrain the average atmospheric stratification is to measure the center-to-limb variation of the linear polarization signals. The dependence of the center-to-limb variations on the atmospheric model is also presented in this paper.  相似文献   

Discriminating Weathering Degree by Integrating Optical Sensor and SAR Satellite Images for Potential Mapping of Groundwater Resources in Basement Aquifers of Semiarid Regions     

Magaia  Luís André  Koike  Katsuaki  Goto  Tada-nori  Masoud  Alaa Ahmed 《Natural Resources Research》2019,28(3):1197-1215

Natural Resources Research - Unlike in coastal and sedimentary basins, regional-scale exploration of groundwater resources using only geophysical methods is costlier in consolidated rocks such as...  相似文献   

Marine biomarkers deposited on coastal land by the 2011 Tohoku-oki tsunami     

Tetsuya Shinozaki  Shigehiro Fujino  Minoru Ikehara  Yuki Sawai  Toru Tamura  Kazuhisa Goto  Daisuke Sugawara  Tomoya Abe 《Natural Hazards》2015,77(1):445-460

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Expected changes in future agro-climatological conditions in Northeast Thailand and their differences between general circulation models     

Yoshimitsu Masaki  Yasushi Ishigooka  Tsuneo Kuwagata  Shinkichi Goto  Shinji Sawano  Toshihiro Hasegawa 《Theoretical and Applied Climatology》2011,106(3-4):383-401

We have studied future changes in the atmospheric and hydrological environments in Northeast Thailand from the viewpoint of risk assessment of future cultural environments in crop fields. To obtain robust and reliable estimation for future climate, ten general circulation models under three warming scenarios, B1, A1B, and A2, were used in this study. The obtained change trends show that daily maximum air temperature and precipitation will increase by 2.6°C and 4.0%, respectively, whereas soil moisture will decrease by c.a. 1% point in volumetric water content at the end of this century under the A1B scenario. Seasonal contrasts in precipitation will intensify: precipitation increases in the rainy season and precipitation decreases in the dry season. Soil moisture will slightly decrease almost throughout the year. Despite a homogeneous increase in the air temperature over Northeast Thailand, a future decrease in soil water content will show a geographically inhomogeneous distribution: Soil will experience a relative larger decrease in wetness at a shallow depth on the Khorat plateau than in the surrounding mountainous area, reflecting vegetation cover and soil texture. The predicted increase in air temperature is relatively consistent between general circulation models. In contrast, relatively large intermodel differences in precipitation, especially in long-term trends, produce unwanted bias errors in the estimation of other hydrological elements, such as soil moisture and evaporation, and cause uncertainties in projection of the agro-climatological environment. Offline hydrological simulation with a wide precipitation range is one strategy to compensate for such uncertainties and to obtain reliable risk assessment of future cultural conditions in rainfed paddy fields in Northeast Thailand.  相似文献   

Evidence for ocean water invasion into the Chicxulub crater at the Cretaceous/Tertiary boundary     

Kazuhisa Goto  Ryuji Tada  Eiichi Tajika  Timothy J. Bralower  Takashi Hasegawa  Takafumi Matsui 《Meteoritics & planetary science》2004,39(8):1233-1247

Abstract— The possibility of ocean water invasion into the Chicxulub crater following the impact at the Cretaceous/Tertiary boundary was investigated based on examination of an impactite between approximately 794.63 and 894.94 m in the Yaxcopoil‐1 (Yax‐1) core. The presence of cross lamination in the uppermost part of the impactite suggests the influence of an ocean current at least during the sedimentation of this interval. Abundant occurrence of nannofossils of late Campanian to early Maastrichtian age in the matrices of samples from the upper part of the impactite suggests that the carbonate sediments deposited on the inner rim margin and outside the crater were eroded and transported into the crater most likely by ocean water that invaded the crater after its formation. The maximum grain size of limestone lithics and vesicular melt fragments, and grain and bulk chemical compositions show a cyclic variation in the upper part of the impactite. The upward fining grain size and the absence of erosional contact at the base of each cycle suggest that the sediments were derived from resuspension of units elsewhere in the crater, most likely by high energy currents association with ocean water invasion.  相似文献   

The 2011 Tohoku-oki Earthquake Tsunami: Similarities and Differences to the 869 Jogan Tsunami on the Sendai Plain   总被引：1，自引：0，他引：1  

Daisuke Sugawara  Fumihiko Imamura  Kazuhisa Goto  Hideaki Matsumoto  Koji Minoura 《Pure and Applied Geophysics》2013,170(5):831-843

A post-tsunami field survey following the 2011 Tohoku-oki Earthquake Tsunami was carried out to asses inundated area in Sendai Plain, Northeast Japan. The type of inundation was classified into two categories (major and minor) according to the amount of accumulated debris, garbage and sediment. Major and minor inundations were identified up to 4 and 5 km from the coastline, respectively. Many artificial geomorphological features, such as roadway embankments and canals, were believed to have affected the run-up process of the tsunami. The inundation area of the 2011 tsunami on the Sendai Plain is compared with that of the 869 Jogan tsunami, which was reconstructed using numerical modeling based on available historical and geological records. The inundation area of the 2011 Tohoku-oki tsunami is comparable to that of the 869 Jogan tsunami, although a direct comparison is difficult due to differences in geomorphological contexts between the paleo period and the present.  相似文献   

266 E+A galaxies selected from the Sloan Digital Sky Survey Data Release 2: the origin of E+A galaxies   总被引：1，自引：0，他引：1  

Tomotsugu Goto 《Monthly notices of the Royal Astronomical Society》2005,357(3):937-944

E+A galaxies are characterized as galaxies with strong Balmer absorption lines but without any [O  ii ] or Hα emission lines. The existence of strong Balmer absorption lines indicates that E+A galaxies have experienced starburst within the past one gigayear. However, the lack of [O  ii ] and Hα emission lines indicates that E+A galaxies do not have any on-going star formation. Therefore, E+A galaxies are interpreted as post-starburst galaxies. For many years, however, it has been a mystery why E+A galaxies started starburst and why they quenched star formation abruptly. Using one of the largest samples of 266 E+A galaxies carefully selected from the Sloan Digital Sky Survey Data Release 2, we have investigated the environment of E+A galaxies from 50 kpc to 8 Mpc scale, i.e. from a typical distance to satellite galaxies to the scale of large-scale structures. We found that E+A galaxies have an excess of local galaxy density only at a scale of <100 kpc (with a 2σ significance), but not at the cluster scale (∼1.5 Mpc) nor at the scale of large-scale structure (∼8 Mpc). These results indicate that E+A galaxies are not created by the physical mechanisms associated with galaxy clusters or the large-scale structure, but are likely to be created by dynamical interaction with closely accompanying galaxies at a <100 kpc scale. The claim is also supported by the morphology of E+A galaxies. We have found that almost all E+A galaxies have a bright compact core, and that ∼30 per cent of E+A galaxies have dynamically disturbed signatures or tidal tails, which quite strongly suggest the morphological appearance of merger/interaction remnants.  相似文献   

Are passive spiral galaxies truly 'passive' and 'spiral'? A near-infrared perspective     

Chisato Yamauchi  Tomotsugu Goto 《Monthly notices of the Royal Astronomical Society》2004,352(3):815-822

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Japan’s <Emphasis Type="Italic">Jishu-bosai-soshiki</Emphasis> community activities: analysis of its role in participatory community disaster risk management     

Robert Bajek  Yoko Matsuda  Norio Okada 《Natural Hazards》2008,44(2):281-292

Jishu-bosai-soshiki, or Jishubo for short, with a literal meaning of “autonomous organization for disaster reduction”, is a neighborhood association for disaster preparedness and rescue activity. In this paper, the role of Jishubo in the context of participatory disaster management in Japan is discussed. Although the formation of Jishubo is not legally mandated, local governments exercise a great deal of persuasion on the inhabitants of their community to organize and participate in disaster management activities. Therefore, participants in Jishubo activities tend to be guided and mobilized with a soft touch by local governments rather than being truly self-motivated, with the objective of reducing disaster risks in their residential areas. There have been several studies on community participatory management conducted in a number of countries, including New Zealand, the USA and Europe, which will serve as a reference in our study. However interesting, the cultural comparison of the “Western” and “Japanese” approaches to community disaster management, is beyond the scope of this paper, the aim of which is to determine a case of community disaster management in Japan. This paper addresses the background behind the development of Jishubo and discusses the uniqueness and limits of this softly mobilized participatory movement in Japan. Based on a case study in Kishiwada City, Osaka, the motivations driving people to participate in disaster management activities organized for Jishubo members is examined. In conclusion, we derive some policy implications and suggest possible approaches for improving the effectiveness of Jishubo and increasing the motivation of people to participate. We also propose that the roles of administrative bodies in Japan, such as non-profit organizations, be better incorporated into community’s participatory disaster reduction activities.  相似文献