花东海盆综合地震探测及其重要的构造意义          下载免费PDF全文

赵明辉  王强  杨富东  张佳政  高红芳  孙龙涛  刘思青  张光学 《地球科学》2021,46(1):359-368

花东海盆位于欧亚板块与菲律宾海板块交汇处,是现今西太平洋俯冲体系中唯一遗留的早白垩纪洋盆,是研究西太平洋俯冲构造演化与动力学机制的一个关键区域.前期研究发现,关于花东海盆的基础科学问题迫切需要解决:花东海盆的性质、年龄及形成演化历史如何?南北走向的加瓜海脊是花东海盆的东部边界吗?其隆升机制和构造属性如何?花东海盆的西部边界是马尼拉俯冲带吗?其各构造单元流体作用及其与花东海盆的构造关系如何?为了解决上述科学问题,在花东海盆开展主动源与被动源的综合地球物理探测和地质采样是非常必要的.一方面,可以采用纵/横波联合反演方法获取花东海盆及其东/西边界的深达地幔的精细速度结构,为构建西太平洋俯冲构造体系跨圈层的构造演化模式提供重要的地质地球物理证据,另一方面,为中国未来在花东海盆大洋钻探计划提供重要的基础数据.   相似文献   

浙江沿海潜在区域地震海啸风险分析   总被引：3，自引：2，他引：1  

毛献忠  祝倩  Wei Yong 《海洋学报》2015,37(3):37-45

采用COMCOT海啸模型建立三重网格模型模拟了2011年3月11日日本东北部9.0级地震引发的海啸发生、发展以及在我国东南沿海传播过程。震源附近浮标站以及浙江沿海的潮位站实测资料验证结果显示,大部分监测站首波到达时间和海啸波的计算值相差在15%以内,表明模型可较好的模拟海啸在计算域内的传播过程。研究表明日本南海海槽、冲绳海槽以及琉球海沟南部是影响浙江沿海主要的区域潜在震源,通过情景计算分别模拟3个潜在震源9.1级、8.0级和8.7级地震引发的海啸对浙江沿海的海啸风险,计算结果表明,海啸波产生后可在3~8h内传至浙江省沿岸,海啸波达1~3m,最大可达4m,此时浙江沿岸面临Ⅲ~Ⅳ级海啸风险,达到淹没至严重淹没等级。  相似文献   

东海海啸反问题预报模式研究——以日本“3·11”海啸为例     

应超  于普兵  穆锦斌  周华民 《海洋预报》2015,32(3):36-42

采用COMCOT数值模式,将日本东海岸划分为18个单位震源,建立了日本东海岸海啸数据库并用非负约束的最小二乘法建立反问题预报模式。将本模式应用于日本"3·11"海啸,计算所得的海啸初始水位有10 m的抬高与3 m的降低,与前人研究结果基本一致,预报的浮标水位与实测资料符合良好。对比浙江省近岸潮位站实测海啸波高,预报值与实测值偏差较大。若采用反问题反演的震源,通过COMCOT非线性模式求解近岸水位,可以大幅提高预报精度。  相似文献   

Propagation of the Storegga tsunami into ice‐free lakes along the southern shores of the Barents Sea     

Anders Romundset  Stein Bondevik 《第四纪科学杂志》2011,26(5):457-462

Deposits in coastal lakes in northernmost Norway reveal that the Storegga tsunami propagated well into the Barents Sea ca. 8100–8200 years ago. A tsunami deposit – found in cores from five coastal lakes located near the North Cape in Finnmark – rests on an erosional unconformity and consists of graded sand layers and re‐deposited organic remains. Rip‐up clasts of lake mud, peat and soil suggest strong erosion of the lake floor and neighbouring land. Inundation reached at least 500 m inland and minimum vertical run‐up has been reconstructed to 3–4 m. In this part of the Arctic coastal lakes are usually covered by >1 m of solid lake ice in winter. The significant erosion and deposition of rip‐up clasts indicate that the lakes were ice free and that the ground was probably not frozen. We suggest that the Storegga slide and ensuing tsunami happened sometime in the summer season, between April and October. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Potential Tsunami Hazard Associated with the Kerepehi Fault,Firth of Thames,New Zealand     

Chick  L. M.  De Lange  W. P.  Healy  T. R. 《Natural Hazards》2001,24(3):309-318

Geophysical data have identified four submarine segments of the Kerepehi Fault, roughly bisecting a back-arc rift (Hauraki Rift). These segments have been traced through the shallow waters of the Firth of Thames, which lies at the southern end of the Hauraki Gulf, New Zealand. No historical or paleotsunami data are available to assess the tsunami hazard of these fault segments.Analysis of the fault geometry, combined with paleoseismic data for three further terrestrial segments of the Fault, suggest Most Credible Earthquake (MCE) moment magnitudes of 6.5–7.1. Due to the presence of thick deposits of soft sediment, and thesemi-confined nature of the Firth, the MCE events are considered capable of generating tsunami or tsunami-like waves. Two numerical models (finite element and finite difference), and an empirical method proposed by Abe (1995), were used to predict maximum tsunami wave heights. The numerical models also modelled the tsunami propagation.The MCE events were found not to represent a major threat to the large metropolitan centre of Auckland City (New Zealand's largest population centre). However, the waves were a threat to small coastal communities around the Firth, including the township of Thames, and 35,000 ha of low-lying land along the southern shores of the Firth of Thames.The Abe method was found to provide a quick and useful method of assessing the regional tsunami height. However, for sources in water depths < 25 m the Abe method predicted heights 2–4 times larger than the numerical models. Since the numerical models were not intended for simulating tsunami generation in such shallow water, the Abe results are probably a good guide to the maximum wave heights.  相似文献   

Numerical simulation of the 1992 Flores tsunami: Interpretation of tsunami phenomena in northeastern Flores Island and damage at Babi Island   总被引：2，自引：0，他引：2  

Fumihiko Imamura  Edison Gica  Tomoyuki Takahashi  Nobuo Shuto 《Pure and Applied Geophysics》1995,144(3-4):555-568

Numerical analysis of the 1992 Flores Island, Indonesia earthquake tsunami is carried out with the composite fault model consisting of two different slip values. Computed results show good agreement with the measured runup heights in the northeastern part of Flores Island, except for those in the southern shore of Hading Bay and at Riangkroko. The landslides in the southern part of Hading Bay could generate local tsunamis of more than 10 m. The circular-arc slip model proposed in this study for wave generation due to landslides shows better results than the subsidence model, It is, however, difficult to reproduce the tsunami runup height of 26.2 m at Riangkroko, which was extraordinarily high compared to other places. The wave propagation process on a sea bottom with a steep slope, as well as landslides, may be the cause of the amplification of tsunami at Riangkroko. The simulation model demonstrates that the reflected wave along the northeastern shore of Flores Island, accompanying a high hydraulic pressure, could be the main cause of severe damage in the southern coast of Babi Island.  相似文献   

Tsunami deposits from the 1993 Southwest Hokkaido earthquake and the 1640 Hokkaido Komagatake eruption,northern Japan   总被引：1，自引：0，他引：1  

Yuichi Nishimura  Naomichi Miyaji 《Pure and Applied Geophysics》1995,144(3-4):719-733

The southwest Hokkaido tsunami of July 12th, 1993, left continuous onshore sand deposits along the west coast of Oshima Peninsuka, Hokkaido, northern Japan. We investigated spatial distribution and lithofacies of the new tsunami deposits for its identification of ancient tsunami deposits. An eyewitness acount and bent plants helped our interpretation of the onshore tsunami behavior. We regard the following properties as typical of the coastal tsunami sand deposits: (1) The deposits cover the surface almost continuously on gentle topography. (2) Deposit thicknesses and mean grain sizes descrease with distance from the sea. (3) Deposit thicknesses and lithofacies vary greatly across local surface undulation. (4) Graded bedding reflecting tsunami runup and backwash is present in thick deposits. (5) The deposits are widely distributed along the coast and extend inland several tens of meters to 100 m. We examined a candidate for the paleo-tsunami deposits associated with the 1640 Komagatake eruption, and confirmed that the similar patterns are typical of ancient tsunami deposits.  相似文献   

Magnitude scale for the Central American tsunamis     

Tokutaro Hatori 《Pure and Applied Geophysics》1995,144(3-4):471-479

Based on the tsunami data in the Central American region, the regional characteristic of tsunami magnitude scales is discussed in relation to earthquake magnitudes during the period from 1900 to 1993. Tsunami magnitudes on the Imamura-Iida scale of the 1985 Mexico and 1992 Nicaragua tsunamis are determined to bem=2.5, judging from the tsunami height-distance diagram. The magnitude values of the Central American tsunamis are relatively small compared to earthquakes with similar size in other regions. However, there are a few large tsunamis generated by low-frequency earthquakes such as the 1992 Nicaragua earthquake. Inundation heights of these unusual tsunamis are about 10 times higher than those of normal tsunamis for the same earthquake magnitude (M _s =6.9–7.2). The Central American tsunamis having magnitudem>1 have been observed by the Japanese tide stations, but the effect of directivity toward Japan is very small compared to that of the South American tsunamis.  相似文献   

Finite element modeling of the July 12, 1993 Hokkaido Nansei-Oki tsunami   总被引：1，自引：0，他引：1  

Edward P. Myers  António M. Baptista 《Pure and Applied Geophysics》1995,144(3-4):769-801

A fault plane model and a finite element hydrodynamic model are applied to the simulation of the Hokkaido Nansei-Oki tsunami of July 12, 1993. The joint performance of the models is assessed based on the overall ability to reproduce observed tsunami waveforms and to preserve mass and energy during tsunami propagation. While a number of observed characteristics of the waveforms are satisfactorily reproduced (in particular, amplitudes and arrival times at tidal gauges relatively close to the source, and general patterns of energy concentration), others are only marginally so (notably, wave periods at the same gauges, and wave heights along Okushiri); differences between observations and simulations are traceable to both the fault plane and the hydrodynamic models. Nonnegligible losses of energy occur throughout the simulated tsunami propagation. These losses seem to be due to a combination of factors, including numerical damping and possible deficiencies of the shallow water equations in preserving energy.  相似文献   

菲律宾大马尼拉地区海水入侵研究分析     

王晖 《安徽地质》1995,(1)

本文阐述了菲律宾大马尼拉地区的地貌、气候、水文、地质等背景情况；介绍区内的地下水质水介质类型及含水层发育情况、富水性和导水性、地下水水力性质、水化学特征和补排条件以及地下水的开采情况和需求量，从而分析了大马尼拉地区海水的机理。  相似文献