基于MOST传播模型的中国边缘海近岸水域海啸强度评估研究

发布时间：2018-01-07 19:05

本文关键词：基于MOST传播模型的中国边缘海近岸水域海啸强度评估研究　出处：《中国海洋大学》2015年博士论文　论文类型：学位论文

【摘要】：海啸是造成人员伤亡和经济损失最严重的自然灾害之一。基于Method of Splitting Tsunami (MOST)数值模型的海啸淹没预报系统能够模拟海啸的产生、传播和淹没过程,实时地进行海啸的预报预警工作。多次历史海啸的实测值与数值模拟值的比较结果证明了该模型的有效性和准确性。该预报系统整合了三个关键组分：海啸的实时深海观测、基于深海观测和海啸传播数据库的海啸源反演、高精度淹没模型计算爬坡。本文基于此模型研究了海啸波信号波的实时提取、全球海啸传播数据库的构建及中国边缘海近岸水域海啸振幅强度评估三个问题。海啸事件发生过程中,海啸探测仪DART(?)记录的海面高度信号中包含潮汐信号、海啸波信号和背景噪声,实时预报系统需要在最短的时间内分离出海啸波信号从而反演海啸源,进而数值模拟海啸数值传播及上岸过程。本文采用经验模态分解(Empirical Mode Decomposition, EMD)方法解决这个问题,此方法适于分解非线性非平稳信号。首先基于经典EMD方法提出了线性算子EMD (LO-EMD)算法,即在高阶导数空间中给出本征模态函数(Intrinsic Mode Functions, IMFs)的定义并转化为优化问题,利用线性算子表示出IMFs。相比于经典EMD方法,此方法在分辨率、模态混淆及抗噪性问题方面有所改进。将LO-EMD方法应用到从海面高度模拟信号分离海啸波信号问题,相比调和分析等方法,此方法采用较短的数据序列就能够达到较高的分解准确度。分离得到的海啸波信号与海啸传播数据库中的海啸源函数结合反演出海啸源,从而为进一步的海啸上岸数值模拟提供初始和边界条件。目前的海啸传播数据库分别覆盖太平洋、大西洋以及印度洋,模拟的海啸传播时间在24 h-36 h。本文基于MOST海啸传播模型,采用全球地形网格以及不同于构建太平洋海啸传播数据库时采用的边界条件,提出全球海啸传播数据库的构建。通过比较一维、二维数值模型的解析解与数值解验证了边界条件的有效性。以2011年3月11日发生的日本海啸为实例,DART(?)实测值与采用数据库计算得到的结果比较表明：计算网格的更新使得对于远离海啸源的一些DART(?)站及验潮站处初始海啸波数值计算结果有改善,边界条件的改变对于提高后续波的模拟结果有影响。同时模拟结果验证了海啸振幅和传播速度在深海中的传播是线性的;采用新边界条件时,MOST模型的数值耗散更少。收集Global CMT地震目录中对中国沿海存在海啸威胁的历史地震,根据记录的地震参数计算MOST模型的输入参数。采用MOST模型模拟五次有实测海啸记录的历史地震产生的海啸,实测记录与数值模拟结果的比较说明,采用历史地震记录计算的作为MOST模型的输入参数,并据此数值模拟历史海啸,该方法是可行性的。MOST模型与Boussinesq模型的比较结果确定了使用MOST模型模拟历史地震引发的海啸增水时在中国附近海域采用1 arc min的计算网格,并采用50 m水深处的海啸振幅对中国边缘海近岸水域海啸振幅强度进行评估。对中国边缘海近岸水域海啸振幅进行统计分析并计算长期重现值,给出长期重现期下中国沿海容易遭受海啸危害的海域。广义Pareto分布(GPD)的阈值选择方法验证了采用7级及以上的历史地震作为研究对象是合理的。7级及以上历史地震的发生频次采用Poisson分布拟合,历史地震矩震级和离岸海啸振幅的一维概率分布分别采用Poisson-GPD和Poisson-Lognormal分布拟合。在假设2011年3月11日日本海啸的重现期为500年的条件下,计算了中国边缘海近岸水域海啸振幅的长期重现值。当重现期为1000年时,广东省东北部海域、福建省西南部海域、台湾除邻接台湾海峡的海域、浙江省东北部海域和上海市附近海域的离岸海啸振幅超过20 cm；特别当重现期为2500年时,广东省东北部海域、福建省西南部海域及台湾高雄南部和东部海域的离岸海啸振幅达到50 cm。采用Gumbel Copula函数构造地震矩震级和中国边缘海近岸水域海啸振幅的联合概率分布并计算联合重现值。当联合重现期为1000年时,海啸振幅超过20 cm的海域在广东省、福建省、台湾、浙江省与上海市附近海域。
[Abstract]:Tsunami is one of the casualties and economic losses of the most serious natural disasters. Method of Splitting Tsunami (MOST) based on the numerical model of tsunami inundation forecasting system can simulate tsunami generation, propagation and inundation process, real-time prediction of the tsunami. And numerical value comparison results prove the validity of the model and the accuracy of multiple historical tsunami observations. The forecast system integrates three key components: real-time ocean observing tsunami, tsunami and tsunami propagation source inversion deep-sea Observation Database Based on high precision submerged climbing. Based on this model calculation model to study the real-time extraction of tsunami wave signal wave, a global tsunami propagation database construction and Chinese Marginal Sea coastal waters tsunami amplitude strength assessment three. During the tsunami, tsunami detectors (DART?) record of the sea Contains the surface height of tidal signal in the signal, the tsunami wave signal and background noise, the real-time forecasting system to isolate tsunami wave signal to inversion of tsunami source in the shortest time, and then the numerical simulation numerical tsunami propagation and landing process. In this paper using empirical mode decomposition (Empirical Mode, Decomposition, EMD) method to solve this problem, this method suitable for the decomposition of nonlinear and non-stationary signal. Based on the classical EMD method is proposed for the linear operator EMD (LO-EMD) algorithm, which is given in the derivative space the intrinsic mode function (Intrinsic Mode, Functions, IMFs) is defined and transformed into an optimization problem, using linear operator expressed IMFs. compared to the classical EMD method, this method in resolution of mode confusion and anti noise problems improved. The LO-EMD method is applied to the simulation of signal separation from sea level tsunami wave signal, compared to adjusted And the analysis method, this method uses short data sequences can achieve high accuracy. The source function decomposition of tsunami tsunami wave signal and tsunami propagation database isolated in combination with inversion of tsunami source, thus ashore for further numerical simulation of tsunami with initial and boundary conditions. The tsunami propagation database respectively. Covering the Atlantic and the Pacific Ocean, India ocean, the tsunami propagation time simulation at 24 h-36 h. based on the MOST tsunami propagation model, the global terrain grid and use different to the construction of the Pacific Tsunami propagation database when the boundary conditions, the construction of global tsunami propagation database. By comparing the one-dimensional analytical solutions of two-dimensional numerical model validation the boundary conditions and numerical tsunami occurred on March 11, 2011 in Japan. For example, DART (?) measured with the calculation data base Compared the results obtained: the grid update makes for some DART away from the tsunami source (?) station and tide station at the initial tsunami wave numerical results have improved, the effect of boundary conditions change to improve the simulation results. At the same time the subsequent wave simulation results verify the propagation of tsunami amplitude and velocity in the deep sea is linear; the new boundary conditions, the numerical dissipation is less. The MOST model of historical earthquakes on coastal China exist tsunami threat collection Global CMT earthquake catalog, parameters of MOST model according to the seismic parameters recorded. Using MOST model to simulate the five time history of earthquake tsunami recorded tsunami, comparison the simulation results illustrate the recording and numerical measurement, using historical earthquake record calculation as the input parameters of the MOST model, and based on the numerical simulation of historical tsunami, the method is available The comparison results of.MOST model and Boussinesq model of computing grid to determine the use of 1 arc min in the waters near the Chinese using MOST model to simulate historical earthquake triggered a tsunami surge, and the tsunami amplitude 50 m deep water to assess the China Marginal Sea coastal waters tsunami amplitude. Statistical analysis was done on the edge of China the Sea coastal waters tsunami amplitude and calculate the long-term return value, given a long-term return period under the China coastal waters. The tsunami hazard to the generalized Pareto distribution (GPD) threshold selection method is verified by the 7 level and above the historical earthquake as the research object is.7 reasonable and above historical earthquake occurrence frequency by Poisson distribution fitting one dimensional probability distribution of historical earthquakes, moment magnitude and offshore tsunami amplitude respectively by Poisson-GPD and Poisson-Lognormal. On the assumption that the distribution of March 2011 11 Japan tsunami return period of 500 years under the condition of long-term value of Chinese Marginal Sea coastal waters tsunami amplitude re calculated. When the return period of 1000, in the northeast of Guangdong Province, Fujian Province, southwest area, adjacent to the Taiwan Strait in Taiwan waters offshore tsunami amplitude near the sea in Zhejiang province north of the east the sea and the city of Shanghai is more than 20 cm; especially when the return period of 2500, the northeast area of Guangdong Province, offshore tsunami amplitude waters southwest of Fujian and Taiwan in southern Kaohsiung and the Eastern Sea reached 50 cm. using the Gumbel Copula function to construct seismic moment magnitude and Chinese Marginal Sea coastal waters tsunami amplitude of the joint probability distribution and calculate the joint return value. When the joint return period of 1000, tsunami amplitude is more than 20 cm area in Guangdong Province, Fujian Province, Taiwan, near the sea area of Zhejiang province and Shanghai city.

【学位授予单位】：中国海洋大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P731.25

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