Regional economic impact analysis of earthquakes in northern Taiwan and its implications for disaster reduction policies

The direct damage caused by earthquakes, such as impaired buildings, may interfere with normal business operations and disrupt the function of the industrial chain. Such economic impacts can be evaluated using the input–output analysis developed by Leontief. In this paper, two scenario earthquakes in northern Taiwan both with a return period of 475 years—the Hsinchu Hsincheng and the Yilan Nan-ao earthquakes—are simulated. The results show that the economic impact caused by the Hsincheng earthquake is greater than that resulting from the Nan-ao earthquake, which should be the major scenario considered for the disaster reduction plan. The industries affected the most are the manufacturing, food services and entertainment, storage and retail trade, and public and construction industries. The Nan-ao earthquake causes relatively more losses in the food services and entertainment industries. Most of the repercussion effects of these industries are in the central and southern parts of Taiwan. The loss to the manufacturing sector and its repercussion effects are enormous. Therefore, the government should make it a first priority to encourage the manufacturing sector to implement earthquake mitigations, such as a seismic retrofit, or to provide a seismic evaluation, which can enable firms to engage in mitigation voluntarily. The measure needed to reduce the loss in agriculture is that the government can purchase agricultural products in central and southern Taiwan following the disaster and offer them to survivors in northern Taiwan.     

高阶统计量在探地雷达数据处理中的应用

用高阶统计量方法对探地雷达数据进行处理,基本思路是采用信号识别与检测中的高阶统计量参数,对不同模型的探地雷达数据记录进行处理与重构,结果表明不同模型具有不同阶数的高阶统计量特征。模型实验与实际应用都表明,高阶统计量对压制背景噪声和多次反射波有较好的效果。     

Assimilation and Simulation of Typhoon Rusa （2002） Using the WRF System

Using the recently developed Weather Research and Forecasting (WRF) 3DVAR and the WRF model, numerical experiments are conducted for the initialization and simulation of typhoon Rusa (2002).The observational data used in the WRF 3DVAR are conventional Global Telecommunications System (GTS) data and Korean Automatic Weather Station (AWS) surface observations. The Background Error Statistics (BES) via the National Meteorological Center (NMC) method has two different resolutions, that is, a 210-km horizontal grid space from the NCEP global model and a 10-km horizontal resolution from Korean operational forecasts. To improve the performance of the WRF simulation initialized from the WRF 3DVAR analyses, the scale-lengths used in the horizontal background error covariances via recursive filter are tuned in terms of the WRF 3DVAR control variables, streamfunction, velocity potential, unbalanced pressure and specific humidity. The experiments with respect to different background error statistics and different observational data indicate that the subsequent 24-h the WRF model forecasts of typhoon Rusa‘s track and precipitation are significantly impacted upon the initial fields. Assimilation of the AWS data with the tuned background error statistics obtains improved predictions of the typhoon track and its precipitation.     

黑潮营养盐输入对东海陆架浮游生态系统影响的模型研究

黑潮是东海陆架主要的外源营养盐来源之一。本文建立了一个物理-生化耦合的三维生态动力学模型,通过敏感性实验分析了黑潮营养盐输入对东海浮游生态系统的影响,分区域、水层和季节对黑潮输入营养盐的贡献进行了统计分析。主要得到如下结论:(1)黑潮对东海陆架营养盐的影响主要集中在整个外陆架和中陆架的中北部,从垂向分布来看,对外陆架影响主要在50m以深的中下层,而对中陆架的影响在次表层(20—50m)和中下层都较为显著,黑潮对东海陆架营养盐输入的总量,冬季略高于夏季。(2)黑潮对东海浮游植物的贡献冬夏两季存在较大差异,冬季叶绿素的增量主要集中在外陆架的中北部和中陆架的中部,分布在表层(0—20m)和次表层;而夏季则主要在外陆架的中部、中陆架的中北部和内陆架的北部,除了内陆架北部以外都以次表层为主。     

Low-frequency acoustic wave-scattering phenomena under ice cover

Studies on low-frequency acoustic wave-scattering phenomena due to under-ice roughness made by utilizing a rough, thin-ice plate model are presented. The model naturally divides the reflected field solution into specular and off-specular components. The model for specular components can give an excellent propagation loss prediction if the combined effects of under-ice roughness scattering, ice absorptions, and ice thickness are taken into account. The model for scattered or off-specular components is evaluated for a point source and point receiver geometry to study various spreading phenomena     

Seismic isolation of rigid cylindrical tanks using friction pendulum bearings

Storage tanks are vulnerable to earthquakes, as numerous major earthquakes have demonstrated. The trend of recent revisions to make seismic design criteria for large‐scale industrial storage tanks increasingly stringent has made development of cost‐effective earthquake‐resistant design and retrofit techniques for industrial tanks imperative. This study assesses the feasibility of seismic base isolation for making liquid‐filled storage tanks earthquake resistant. The sliding‐type friction pendulum seismic (FPS) bearings are considered rather than the elastomeric bearings because the dynamic characteristics of an FPS‐isolated tank remain unchanged regardless of the storage level. This work has devised a hybrid structural‐hydrodynamic model and solution algorithm, which would permit simple, accurate and efficient assessment of the seismic response of rigid cylindrical storage tanks in the context of seismic isolation. Extensive numerical simulations confirm the effectiveness of seismic base isolation of rigid cylindrical tanks using FPS bearings. Copyright © 2001 John Wiley & Sons, Ltd.     

Gravity change in the Beijing-Tianjin-Tangshan area

A gravity network was established by a crew of gravity measurement in July, 1981, with three LCR gravimeters. The measurement errors are less than 100 nm/s². The detectable changes in gravity with time in the Beijing-Tianjin-Tangshan area are described. The results show that the gravity has increased 1000 nm/s² in Tianjin area where the ground has been subsiding at a rate of 7–8 cm/a and at the center of subsidence gravity has increased. At other stations, such as Baodi, Tangerli, etc., gravity has also increased gradually, but with an amplitude smaller than that of Tianjin. In the area surveyed gravity tendentiously decreases from south-east to north-east.     

Inflow and outflow in a rotating circular container—A laboratory model for the Loop Current of the Gulf of Mexico

The Loop Current of the Gulf of Mexico is simulated in the laboratory. A circular tank is filled with water and is placed off-center on a rotating table and the flow field is generated by injecting and withdrawing water at two openings on the wall. The free surface becomes parabolic due to balance of gravitational and centrifugal forces, simulating the latitudinal change of the Coriolis parameter (-effect) in the ocean. The flow characteristics depend on the influx and the rate of rotation and can be classified according to non-dimensional parameters (Rossby, Ekman and Froude numbers denoted byR ₀,E andF, respectively). When the influx is small and the rotation rate is large (smallR ₀,E andF) the flow will be almost linear, and the fluid flows along the side-wall boundary layer under constraint of the -effect. For a very large influx (largeR ₀ andE) inertial forces become very large compared to the Coriolis force and the flow behaves like a potential flow. The flow studied had characteristics between these two extreme cases and hasR ₀ andF similar to the Gulf circulation, though similarity inE is ambiguous. Photographs of the flow indicate that the inflow penetrates further into the interior when the rotation rate is increased while the influx is kept constant. The numerical analysis of the non-linear vorticity equation confirms this for the parameters corresponding to the experiment. In addition, the photographs reveal eddies embedded on both sides of the main stream, particularly near the inflow region. These eddies are intensified and become uniform in size as the influx increases. It is pointed out that such eddies were actually observed near the Loop Current north of the Yucatan Straits.     

Vortex boundary layer under quadratic surface stress

The influences of the quadratic surface stress on the two-dimensional structure of boundary-layer flows in hurricane-like and tornado-like vortices are investigated by solving the nonlinear boundary-layer equations in the vertical direction through power series expansion and expressing the expansion coefficients in terms of parameters of the vortex profile. It is found that the series solutions converge rapidly and the vertical velocity w_bcreated by the boundary-layer flow is upward everywhere for the hurricane type vortex, with the maximum vertical velocity w_bmoccurring inside the radius of maximum tangential wind. This result is of utmost importance for the hurricane development problem on account of the organizing influence of w_bon cumulus convection and latent heat release in the conditionally unstable tropical atmosphere. On the other hand, the vertical velocity created by the boundary layer of the pure potential vortex with zero absolute vorticity is downward.