排序方式： 共有3条查询结果，搜索用时 0 毫秒
1
1.
Following the recent unexpected earthquake events of 2004 and 2011, it can be cautiously extrapolated that all major subduction zones bearing the capacity to produce mega-earthquake events will eventually do so given enough time, irrespective of the lack of such in the relatively short historical record. This notion has led to an effort of assigning maximum earthquake magnitudes to all major subduction zones, either based on geological constraints or based on size–frequency relations, or a combination of both. In this study, we utilize the proposed maximum magnitudes to assess tsunami hazard in Central California in the very long return periods. We also assessed tsunami hazard following an alternative methodology to calculate maximum magnitudes, which uses scaling relations for subduction zone earthquakes and maximum fault rupture scenarios found in literature. A sensitivity analysis is performed for Central California that is applicable to any coastal site in the Pacific Rim and can readily provide a strong indication for which subduction zones beam the most energy toward a study area. The maximum earthquake scenarios are then narrowed down to a few candidates, for which the initial conditions are examined in more detail. The chosen worst-case scenarios for Central California stem from the Alaska–Aleutian subduction zone that beams more energy and generates the biggest amplitude waves toward the study area. The largest tsunami scenario produces maximum free surface elevations of 15 m and run-up heights greater than 20 m. 相似文献
2.
In this paper, a set of models responsible for hydrodynamics, sediment transport, and morphological evolution are introduced with their theoretical backgrounds, and it is explained how they are fully connected through a two-way coupling to yield an integrated sediment transport model applicable to tsunami cases. In particular, a fully nonlinear Boussinesq model with bottom shear-induced rotational terms is chosen for the hydrodynamic model in order to provide a better physical approximation of tsunami-related, near-bed hydrodynamics in the nearshore. A finite-volume scheme, stable and suitable for phase-resolving model runs longer than 10 simulated hours, is adopted in the numerical discretization. The accuracy and applicability of the developed model are investigated through numerical tests on various sediment problems in the shallow region. Calculated results agree well with existing experimental records. Finally, an ocean-wide, field-scale simulation of the 2011 Tohoku-oki tsunami is attempted, with a focus on the localized effects of tsunami-induced morphological changes at Crescent City Harbor and Santa Cruz Harbor (USA). Consistent with the reported observations, strong and vortical velocity fields are generated through the model and result in significant changes in morphological configurations. Depth variations and areas of scouring and deposition are compared between modelled and observed records, and the results are discussed. © 2019 John Wiley & Sons, Ltd. 相似文献
3.
Subsidence has been affecting many cities around the world, such as Nagoya (Japan), Venice (Italy), San Joaquin Valley and Long Beach (California), and Houston (Texas). This phenomenon can be caused by natural processes and/or human activities, including but not limited to carbonate dissolution, extraction of material from mines, soil compaction, and fluid withdrawal. Surface deformation has been an ongoing problem in the Houston Metropolitan area because of the city’s location in a passive margin where faulting and subsidence are common. Most of the previous studies attributed the causes of the surface deformation to four major mechanisms: faulting, soil compaction, salt tectonics, and fluid withdrawal (groundwater withdrawal and hydrocarbon extraction). This work assessed the surface deformation in the greater Houston area and their possible relationship with fluid withdrawal. To achieve this goal, data from three complimentary remote sensing techniques Global Positioning System (GPS), Light Detection and Ranging (LiDAR), and Interferometric Synthetic Aperture Radar were used. GPS rates for the last 17 years show a change in surface deformation patterns. High rates of subsidence in the northwestern areas (up to ~4 cm/year) and signs of uplift in the southeast are observed (up to 2 mm\year). High rates of subsidence appear to be decreasing. Contrary to previous studies in which the location of subsidence appeared to be expanding toward the northwest, current results show that the area of subsidence is shrinking and migrating toward the northeast. Digital elevation model generated from airborne LiDAR, revealed changes between salt domes and their surrounding areas. The persistent scatterer interferometry was performed using twenty-five (25) European remote sensing-1/2 scenes. Rates of change in groundwater level and hydrocarbon production were calculated using data from 261 observation wells and 658 hydrocarbon wells. A water level decline of 4 m/year was found in area of highest subsidence, this area also show ~70 million m3/year of hydrocarbon extraction. This study found strong correlation between fluid withdrawals and subsidence. Therefore, both groundwater and hydrocarbon withdrawal in northwest Harris County are considered to be the major drivers of the surface deformation. 相似文献
1