The December 26, 2004, off the west coast of northern Sumatra, Indonesia, M_W=9.0, earthquake and the critical-point-like model of earthquake preparation

Introduction The unexpected December 26, 2004, off the west coast of northern Sumatra, Indonesia, MW=9.0 earthquake, which caused devastating tsunami around the Indian Ocean, reminds seis-mologists of the difficulty of earthquake forecast and/or prediction. For seismologists this earth-quake is almost completely unexpected, because there was neither forecasting (which means the estimation of the future earthquake rate as a function of location, time, and magnitude) nor predic-tion (forecasti…     

基于MapXtreme的大庆供水管网系统的设计与实现

该文介绍了基于MapXtremeforNT的WebGIS应用专题系统———大庆供水管网信息系统的设计与实现 ,阐述该系统的体系结构、功能设计 ,并对MapXtreme的实现机理进行分析 ,同时研究客户端和服务器端通讯技术及智能关阀等功能的实现方法。     

基于·NET的MapXtreme2004矢量地图符号扩展

MapInfo软件是应用十分广泛的主流GIS软件之一,MapXtreme2004是MapInfo公司最新推出的面向网络地理信息发布的优秀组件。但是MapXtreme2004组件本身符号库功能相对薄弱,且矢量符号库的扩展比较困难,从而在一定程度上限制了其应用。对此,本文提出了一种基于.NET的MapXtreme2004矢量地图符号扩展新思路,即算法绘制、图元合并以及图层存储相结合的方法,详细讨论了该方法的关键技术点、实现思路和步骤,给出了实际应用效果示例。     

基于.NET和MapXtreme的公交查询系统的设计与实现

本文详细介绍了基于.NET框架、利用MapXtreme二次开发组件,设计和实现多种情况下的公交换乘查询算法的过程,提出了公交查询系统的解决方案。其中,在数据表的设计上建立了路段与站点的一种一一对应关系的拓扑关系,简化了站点和线路查询的实现过程。在最优换乘方案的设计上采用的是一种基于树形结构的遍历算法,具有较强的实用价值。     

Numerical Simulation of Tsunamis on the Tamil Nadu Coast of India

The State of Tamil Nadu was the most affected region in India during the tsunami of December 26, 2004, in the Indian Ocean, in terms of loss of life and damage. Numerical simulation was made for three tsunamis, the December 26, 2004, event, the Sumatra tsunami of 1833, and a hypothetical tsunami originating in the Andaman-Nicobar region. Since inundation is not included in these simulations, the tsunami amplitudes were deduced at the 10m depth contour in the ocean, off several locations on the coast of Tamil Nadu. The computed amplitudes appear reasonable as compared to known tsunami amplitudes from past events.     

Source parameters of the 2004 Kaliningrad earthquakes

An analysis of source parameters of the two unexpected earthquakes from the Kaliningrad (Russia) area is presented. The earthquakes occurred on 21 September 2004 at 11:05:01 and 13:32:31 UT, respectively. The first event was located at the latitude φ = 54.924°N and the longitude λ = 20.120°E, with a depth h = 16 km, and the second event at φ = 54.876°N, λ = 20.120°E and h = 20 km. Magnitudes Mw of the two events were very similar: 5.1 and 5.2. The magnitude values reported by various international data centers have been meaningfully different. The reason is the presence of high-frequency components in Z velocity component of the S wavefield. They were observed along the direction defined by two stations, BLEU in Sweden and SUW in Poland, located in opposite sides of the source. Along the direction perpendicular to it, the effects are relatively very small. The high-frequency waves are understood to mean components in the 6–8 Hz band for event 1 and 2-4 Hz for event 2. The effects in question are also clearly visible on displacement spectrograms. The magnitude values calculated at such stations from S-wave amplitudes or from seismic spectra are clearly overestimated and are close to 6. Therefore, we made a careful selection of channels in order to determine the spectral parameters and, on this basis, the source parameters. The size of the source is relatively small, of about 2 km. The closest seismic station is at 100 source radii from the source. One can clearly see the effect of the TT zone which markedly reduces the seismic moment value for seismic stations laying on the opposite sides of the source. Both events have very similar spatial distributions of the source parameters: magnitude, seismic moment and radius.     

Seismic Records of the 2004 Sumatra and Other Tsunamis: A Quantitative Study

Following the recent reports by Yuan et al. (2005) of recordings of the 2004 Sumatra tsunami on the horizontal components of coastal seismometers in the Indian Ocean basin, we build a much enhanced dataset extending into the Atlantic and Pacific Oceans, as far away as Bermuda and Hawaii, and also expanded to five additional events in the years 1995–2006. In order to interpret these records quantitatively, we propose that the instruments are responding to the combination of horizontal displacement, tilt and perturbation in gravity described by Gilbert (1980), and induced by the passage of the progressive tsunami wave over the ocean basin. In this crude approximation, we simply ignore the island or continent structure, and assume that the seismometer functions de facto as an ocean-bottom instrument. The records can then be interpreted in the framework of tsunami normal mode theory,and lead to acceptable estimates of the seismic moment of the parent earthquakes. We further demonstrate the feasibility of deconvolving the response of the ocean floor in order to reconstruct the time series of the tsunami wave height at the surface of the ocean, suggesting that island or coastal continental seismometers could complement the function of tsunameters.     

基于MapXtreme的校园WebGIS系统实现

万维网地理信息系统(WebGIS)是利用互联网(Internet)来扩展和完善地理信息系统功能的一项新技术，是由地理信息系统和互联网技术相结合而产生的一种新方法。目前，用于开发WebGIS的方法有许多种，文章研究基于MapXtreme的WebGIS实现方法，把MapXtreme与JavaScript及ASP相结合开发WebGIS系统，并将其应用于校园信息查询中。实现基于MapXtreme的校园WebGIS系统。     

基于MapXtreme的水资源管理信息系统研究与开发——以北江流域为例

北江流域是广东省重要的水域之一,随着GIS和网络技术的发展,传统的水资源管理手段和技术正面临着各种挑战.针对当前北江流域的管理现状,在系统分析、设计和开发的实践基础上,从各种技术的实现上多方面探讨地理信息系统、网络技术在水资源管理中的结合与应用问题,为应用系统从传统的单机或Intranet向Internet的跨越积累了经验,同时为水资源管理向可持续发展提供了一套较好方案.