What constitutes successful participatory disaster risk management? Insights from post-earthquake reconstruction work in rural Gujarat,India     

Subhajyoti Samaddar  Norio Okada  Junho Choi  Hirokazu Tatano 《Natural Hazards》2017,85(1):111-138

Although for decades, public participation in disaster risk management has been strongly advocated for, in reality, it remains elusive. Planners and practitioners are still struggling to find ways to meaningfully involve the local community in disaster management programs; so far, apparently successful projects and initiatives have seldom been scaled up or replicated. The reason for this is that no comprehensive framework for participatory disaster risk management exists, and no systematic evaluation has been made to assess the necessary elements and appropriate paths for meaningful public participation in disaster management. This study attempts to examine the process and identify outcome-based factors that account for successful participatory disaster risk management. To accomplish this, we have evaluated reconstruction projects in earthquake-affected rural Gujarat, India, where the government envisioned a people-centric reconstruction project, but provided no public participation framework or guidelines. As a result, several reconstruction models pursuing different levels and types of public participation ultimately emerged. We selected three dominant reconstruction approaches and examined the extent to which various processes and outcome-based factors were successful in promoting ideal levels of public participation during these reconstruction projects. This study is considered an example of pioneering research in defining factors that account for successful participatory disaster risk management.  相似文献   

Impacts of climate change on growth, migration and recruitment success of Japanese sardine (Sardinops melanostictus) in the western North Pacific     

Takeshi Okunishi  Shin-ichi Ito  Taketo Hashioka  Takashi T. Sakamoto  Naoki Yoshie  Hiroshi Sumata  Yumiko Yara  Naosuke Okada  Yasuhiro Yamanaka 《Climatic change》2012,115(3-4):485-503

We developed a multi-trophic level ecosystem model by coupling physical, biogeochemical-plankton and fish models. An oceanic general circulation model was coupled with a lower trophic level ecosystem model and a Japanese sardine migration model, and applied to the western North Pacific. To investigate the impact of global warming on the pelagic fish ecosystem, such as Japanese sardine, we conducted numerical experiments of growth and migration of Japanese sardine using physical fields for the present day and future with a global warming scenario simulated by a high-resolution climate model. The model results demonstrated possible impacts of global warming on the growth and migration pattern of Japanese sardine. The growths of fish in the current main spawning region under the global warming scenario were significantly slower than those under the present climate scenario. Fish in this region will be at disadvantage for their recruitment under the global warming condition. Prey conditions in the spawning region were projected not to markedly change under global warming condition while water temperature increased. As a result sardine spawning ground was projected to shift towards more north areas. During the feeding migration period in summer, geographical distribution of juveniles fish was projected to shift northwards by one to two degrees latitude under the global warming condition following the change in the distribution of optimal temperature region for feeding. However, this northwards shift of the optimal temperature for feeding was minimized adjacent to the western North Pacific by the cooler water supply by the intensification of the Oyashio.  相似文献   

Tomographic imaging of hydrated crust and mantle in the subducting Pacific slab beneath Hokkaido, Japan: Evidence for dehydration embrittlement as a cause of intraslab earthquakes   总被引：4，自引：3，他引：1  

Junichi Nakajima  Yusuke Tsuji  Akira Hasegawa  Saeko Kita  Tomomi Okada  Toru Matsuzawa 《Gondwana Research》2009,16(3-4):470-481

We estimate detailed three-dimensional seismic velocity structures in the subducting Pacific slab beneath Hokkaido, Japan, using a large number of arrival-time data from 6902 local earthquakes. A remarkable low-velocity layer with a thickness of ~ 10 km is imaged at the uppermost part of the slab and is interpreted as hydrated oceanic crust. The layer gradually disappears at depths of 70–80 km, suggesting the breakdown of hydrous minerals there. We find prominent low-velocity anomalies along the lower plane of the double seismic zone and above the aftershock area of the 1993 Kushiro-oki earthquake (M7.8). Since seismic velocities of unmetamorphosed peridotite are much higher than the observations, hydrous minerals are expected to exist in the lower plane as well as the hypocentral area of the 1993 earthquake. On the other hand, regions between the upper and lower planes, where seismic activity is not so high compared to the both planes, show relatively high velocities comparable to those of unmetamorphosed peridotite. Our observations suggest that intermediate-depth earthquakes occur mainly in regions with hydrous minerals, which support dehydration embrittlement hypothesis as a cause of earthquake in the subducting slab.  相似文献   

Timing and Duration of Hydrothermal in the Oligocene Hamad Cauldron, SW Japan: Evidence from K-Ar Ages of Sericites     

Teyruyoshi Imaoka    Kazuo Nakashima  Testumaru Itaya  Toshinori Okada 《Resource Geology》2001,51(1):55-62

Abstract: Crystallinity, chemical compositions and K-Ar ages of sericites in highly-sericitized granites and associated fissure-filling veins were examined to delineate the timing and duration of the hydrothermal activity in the Oligocene Hamada cauldron in the San-in district, SW Japan. Sericite separates (>2 μm) from the highly-sericitized granites consist mainly of 2M₁ polytype having high crystallinity and low Kübler indices of 0.22–0.35, while those in the fissure-filling veins have lower 2M₁/1Md ratios and crystallinity, and high Kübler indices of 0.29–0.35. This suggests that the sericites in highlysericitized granites were formed at a higher temperature than the vein sericites.
Sericites from the highly-sericitized granites of the Kumogi pluton give K-Ar ages of 30.0±0.7, 30.4±0.7, 30.6±0.7, 30.6±0.7, 32.1±0.7, 32.3±0.7 and 33.0±0.7 Ma (1), while those of the central plutons, 33.8±0.7 and 33.8±0.7 Ma. Sericites in the fissure-filling veins of the Kumogi granite give K-Ar ages of 31.0±0.7, 31.5±0.7, 31.6±0.7, 31.7±0.7 and 32.3±0.7 Ma. Biotite separates from the fresh Kumogi granite give K-Ar ages of 31.7±0.8, 32.0±0.8, 32.7±0.7 and 33.5±0.7 Ma. The K-Ar age data revealed that the hydrothermal alteration began at about 33 Ma and ended by about 30 Ma and that the period of sericite alteration was nearly synchronous with the cooling of the granite intrusions in the Hamada cauldron.
Despite intense hydrothermal alteration, the Oligocene granitoids have not accompanied with any economic base metal mineralization. The bulk chemical analyses of sericite separates in the veins indicate that the post-magmatic fluids were originally barren in heavy metals.  相似文献   

Optimal operation model of a single reservoir with drought duration explicitly concerned     

H. Tatano  N. Okada  H. Kawai 《Stochastic Environmental Research and Risk Assessment (SERRA)》1992,6(2):123-134

In this paper, a new model for a single reservoir operation optimization is proposed. The proposed model can design the optimal operation policy of a reservoir with explicit consideration of drought duration. The authors model this problem by formulating a single-stage loss function as a function of both the reservoir release and drought duration. Thereby the expected loss per period which is calculated based on the above extended single-stage loss function is minimized in infinite time horizon on the basis of Markov decision process (MDP) theory. The reliability indices are estimated as expected loss per period for specified extended loss functions. Finally, the features of the proposed model are illustrated through numerical analysis.  相似文献   

In situ X-ray observations of the decomposition of brucite and the graphite–diamond conversion in aqueous fluid at high pressure and temperature     

T. Okada  W. Utsumi  H. Kaneko  M. Yamakata  O. Shimomura 《Physics and Chemistry of Minerals》2002,29(7):439-445

 An experimental technique to make real-time observations at high pressure and temperature of the diamond-forming process in candidate material of mantle fluids as a catalyst has been established for the first time. In situ X-ray diffraction experiments using synchrotron radiation have been performed upon a mixture of brucite [Mg(OH)₂] and graphite as starting material. Brucite decomposes into periclase (MgO) and H₂O at 3.6 GPa and 1050 °C while no periclase is formed after the decomposition of brucite at 6.2 GPa and 1150 °C, indicating that the solubility of the MgO component in H₂O greatly increases with increasing pressure. The conversion of graphite to diamond in aqueous fluid has been observed at 7.7 GPa and 1835 °C. Time-dependent X-ray diffraction profiles for this transformation have been successfully obtained. Received: 17 July 2001 / Accepted: 18 February 2002  相似文献   

Tectono-metamorphic evolution of the Okcheon Metamorphic Belt, South Korea: Tectonic implications in East Asia   总被引：9，自引：0，他引：9  

Chang Whan Oh  Sung Won Kim  In-Chang Ryu  Toshinori Okada  Hironobu Hyodo  Tetsumaru Itaya 《Island Arc》2004,13(2):387-402

Abstract The tectonic history of the Okcheon Metamorphic Belt (OMB) is a key to understanding the tectonic relationship between South Korea, China and Japan. The petrochemistry of 150 psammitic rocks in the OMB indicates that the depositional environment progressively deepened towards the northwest. These data, combined with the distribution pattern of oxide minerals and the abundance of carbonaceous material, support a half‐graben basin model for the OMB. Biotite and muscovite K–Ar dates from metasediments in the central OMB range from 102 to 277 Ma. K–Ar ages of 142–194 Ma are widespread throughout the area, whereas the older ages of 216–277 Ma are restricted to the metasediments of the middle part of the central OMB. The younger (Cretaceous) ages are only found in metasediments that are situated near the Cretaceous granite intrusions. The 216–277 Ma dates from weakly deformed areas represent cooling ages of M1 intermediate pressure/temperature (P/T) metamorphism. The relationship between age distribution and deformation pattern indicates that the Jurassic muscovite and biotite dates can be interpreted as complete resetting ages, caused by thermal and deformational activities associated with Jurassic granite plutonism. Well‐defined ⁴⁰Ar/³⁹Ar plateau ages of 155–169 Ma for micas from both metasediments and granitic rocks can be correlated with the main Jurassic K–Ar mica ages (149–194 Ma). U–Pb zircon dates for biotite granite from the southwest OMB are 167–169 Ma. On the basis of the predominantly Jurassic igneous and metamorphic ages and the uniformity of d₀₀₂ values for carbonaceous materials in the study area, it is suggested that the OMB has undergone amphibolite facies M2 metamorphism after M1 metamorphism. This low P/T M2 regional thermal metamorphism may have been caused by the regional intrusion of Jurassic granites. The OMB may have undergone tectono‐metamorphic evolution as follows: (i) the OMB was initiated as an intraplate rift in the Neoproterozoic during break‐up of Rodinia, and may represent the extension of Huanan aulacogen within the South China block; (ii) sedimentation continued from the Neoproterozoic to the Ordovician, perhaps with several unconformities; (iii) M1 intermediate P/T metamorphism occurred during the Late Paleozoic due to compression caused by collision between the North and South China blocks in an area peripheral to the collision zone; and (iv) during the Early to Middle Jurassic, north‐westward subduction of the Farallon‐Izanagi Plate under the Asian Plate resulted in widespread intrusion of granites, which triggered M2 low P/T regional thermal metamorphism in the OMB. This event also formed the dextral Honam shear zone at the boundary between the OMB and Precambrian Yeongnam massif.  相似文献   

Imaging the heterogeneous source area of the 2003 M6.4 northern Miyagi earthquake, NE Japan, by double-difference tomography     

Tomomi Okada  Akira Hasegawa  Jun''ichi Suganomata  Norihito Umino  Haijiang Zhang  Clifford H. Thurber 《Tectonophysics》2007,430(1-4):67-81

A shallow M6.4 inland earthquake occurred on 26 July 2003 in the northern part of Miyagi Prefecture, northeastern Japan. This earthquake was a typical inland thrust earthquake, a type that is common in NE Japan. We obtained a detailed seismic velocity structure in the focal area of this earthquake by the double-difference tomography method. Arrival-time data came from temporary seismic stations deployed above the mainshock fault plane. Both the P-wave and S-wave velocities in the hanging wall were lower than those in the footwall. Aftershocks were aligned along a zone where the seismic velocity changes rapidly. This is consistent with the interpretation that the 2003 northern Miyagi earthquake occurred along a fault that acted as a normal fault in the Miocene and has been reactivated as a reverse fault under the present compressional stress regime. The large slip area by the main shock rupture (asperity) corresponds to an area with relatively high P- and S-wave velocities. A zone with low V_p/V_s was detected along the aftershock area. One of the possible causes of this low-V_p/V_s zone is the existence of high-aspect-ratio pores that contain water. Hypocenters of the main shock, largest foreshock, and largest aftershock are also located within the low-V_p/V_s zone.  相似文献   

Empirical Models for Anomalous High-Frequency Arrivals from Deep-Focus Earthquakes in South America     

J. A. Snoke  I. S. Sacks  H. Okada 《Geophysical Journal International》1974,37(1):133-139

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Estimating the spatial distribution of dredged material disposed of at sea using particle-size distributions and metal concentrations     

Tomonari Okada  Claire Mason 《Marine pollution bulletin》2009,58(8):1164-1177

We present a method to estimate the spatial distribution of dredged material disposed of at sea. Using both dredged sediments and samples of sea-bed sediment from near the Rame Head disposal site, Plymouth, UK, we applied entropy analysis to the <63 μm sediment fraction and combined the results with the trace metal data in the same fraction, to form a series of groups. We interpret the distribution of sediments in one group (F1) to approximate the distribution of material affected by the disposal site. This distribution includes locations close to the disposal site, and also locations <4 km to the SE and SW, <6 km to the NW and <2 km to the N. This approach demonstrates the feasibility of using trace metal analysis of particular grain size fractions to reduce uncertainty in interpreting the spatial distribution of impacts of dredge disposal.  相似文献