Documentation and Evaluation of Factors Controlling Seismic Slope Stability Using GIS

摘要：地震诱发滑坡是山区地震引发的一种常见现象。1999年9月21日，台湾池池地震及其后的大余震在整个台湾中部山区造成了1800多次山体滑坡。使这些滑坡对后续研究特别有趣的是，地震激活了700多个自由场加速点的仪器。因此，有了这个记录地面运动的大型数据库，我们现在有了一个独特的机会，可以直接将边坡破坏的程度和类型与震动的震级联系起来，并评估我们基于GIS的模型在区域和局部尺度上评估地震边坡稳定性的能力。能够开发基于GIS的准确预测边坡稳定性模型的主要问题之一是基线信息的分辨率，该基线信息由从各种来源收集的多层数据组成。在台湾，这些数据驻留在赤赤地震数据库分析与管理系统（CEDAMS）中，该系统为赤赤地震数据库中的航空照片、SPOT图像、灾区基本数据集、数字地形图和数字地图等约15-20千兆字节的数据提供在线分析和管理功能。主要问题是确保数据库包含正确类型的信息，并具有足够的准确性，以供将来的分析使用。因此，这项为期一年的工作的直接目标是利用这些大量数据，集中精力收集一小部分滑坡的详细现场数据。将使用基于GPS定位的数字野外测绘技术，以便用更准确的地形信息增加现有数据库。这些信息将被用来定义地形中的陡坡，如斜坡的顶部和底部、河岸、道路切割、山脊或其他突然地表变化的位置。此外，还需要对滑坡陡坡、当地地质和强度特征进行准确的测绘。然后，这些数据将与当地地面运动的最佳解释相结合，以便校准模型。

CMS0085298Title: "Documentation and Evaluation of Factors Controlling Seismic Slope Stability Using GIS"PI: N. SitarInstitution: University of California at BerkeleyAbstract:Seismically triggered landslides are a common phenomena associated with earthquakes in mountainous regions. The September 21, 1999, Chi Chi, Taiwan earthquake and subsequent large aftershocks generated more than 1,800 landslides throughout the central mountain region of Taiwan. What makes these landslides particularly interesting for follow up studies is the fact that the earthquake activated instruments at more than 700 free-field acceleration sites. Consequently, with this large database of recorded ground motions we now have a unique opportunity to directly relate the extent and type of slope failure to the magnitude of shaking and to evaluate our capability of GIS based models to assess seismic slope stability on a regional and local scale.One of the principal problems in being able to develop an accurate predictive GIS based slope stability model is the resolution of the baseline information, which consists of many layers of data collected from various sources. In Taiwan, such data resides in CEDAMS (Chi Chi Earthquake Database Analysis & Management Systems), which provides on-line analysis and management functions for about 15-20 Giga Bytes of data available in the form of aerial photos, SPOT images, basic datasets of disaster areas, Digital Terrain Maps and digital maps in the Chi Chi Earthquake database. The main problem is making sure that the database contains the right type of information with sufficient accuracy for future analyses. Thus, the immediate objective of this one-year effort is to take advantage of this large amount of data and to concentrate on the task of collecting detailed field data on a small subset of the landslides. Digital field mapping techniques based on GPS positioning will be used in order to augment the existing database with more accurate topographic information. This information will be used to define sharp breaks in the terrain, such as the top and toe of the slopes, stream banks, road cuts, ridges or other locations of abrupt surface change. Furthermore, accurate mapping of landslide scarps, local geology, and an assessment of strength characteristics will be needed. These data will then be coupled with best interpretation of the local ground motions in order to calibrate the model.