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Development of a country-wide seismic site-response zonation map for the Netherlands
Natural Hazards and Earth System Sciences ( IF 4.2 ) Pub Date : 2021-08-26 , DOI: 10.5194/nhess-2021-252
Janneke van Ginkel , Elmer Ruigrok , Jan Stafleu , Rien Herber

Abstract. Earthquake site-response is an essential part of seismic hazard assessment, especially in densely populated areas. The shallow geology of the Netherlands consists of a very heterogeneous soft sediment cover, which has a strong effect on seismic wave propagation and in particular on the amplitude of ground shaking, resulting in significant damage on structures despite the fact that the events are of small magnitude. Even though it is a low-to-moderate seismicity area, the seismic risk cannot be neglected, in particular, because shallow induced earthquakes occur. The aim of this study is to establish a nationwide site-response zonation by using the lithostratigraphy, earthquake- and ambient vibration recordings. In the first step, we constrain the parameters (velocity contrast and shear-wave velocity) that are indicative of ground-motion amplification in the Groningen area. For this, we combine ambient vibration and earthquake recordings using resp. the horizontal-to-vertical spectral ratio method (HVSR), borehole empirical transfer functions (ETFs) and amplification factors (AFs). This enables us to define an empirical relationship between measured earthquake amplification from the ETF and AF, and amplification estimated with the HVSR derived from the ambient seismic field. Therewith, we show that the HVSR can be used as a first proxy for amplification. Subsequently, HVSR curves throughout the Netherlands are estimated. The resulting peak amplitudes largely coincide with the in-situ lithostratigraphic sequences and the presence of a strong velocity contrast in the near-surface. Next, sediment profiles representing the Dutch shallow subsurface are categorized into five classes, where each class is representing a level of expected amplification. The mean amplification for each class, and its variability, is quantified using 66 sites with measured earthquake amplification (ETF and AF) and 115 sites with HVSR curves. The site-response (amplification) zonation map for the Netherlands is designed by transforming published geological 3D grid cell models into the five classes and an AF is assigned to most of the classes. This presented site-response assessment on a national scale is important for a first identification of regions with increased seismic hazard potential, for example at locations with mining or geothermal energy activities.

中文翻译:

为荷兰开发全国地震现场响应分区图

摘要。地震场地响应是地震危险性评估的重要组成部分,尤其是在人口稠密地区。荷兰的浅层地质由非常不均匀的软沉积覆盖层组成,这对地震波的传播,特别是对地面震动的幅度有很强的影响,尽管事件的震级很小,但对结构造成了严重的破坏. 即使是中低地震活动区,地震风险也不容忽视,尤其是发生浅层诱发地震。本研究的目的是通过使用岩石地层学、地震和环境振动记录建立全国性的场地响应分区。在第一步中,我们限制了表示格罗宁根地区地面运动放大的参数(速度对比和横波速度)。为此,我们使用 resp 将环境振动和地震记录结合起来。水平垂直光谱比法 (HVSR)、钻孔经验传递函数 (ETF) 和放大系数 (AF)。这使我们能够定义从 ETF 和 AF 测得的地震放大率与从环境地震场导出的 HVSR 估计的放大率之间的经验关系。因此,我们表明 HVSR 可以用作放大的第一个代理。随后,估计了整个荷兰的 HVSR 曲线。由此产生的峰值振幅在很大程度上与原位岩石地层序列和近地表存在强烈的速度对比一致。接下来,代表荷兰浅层地下的沉积物剖面被分为五类,其中每一类代表一个预期的放大水平。每个类别的平均放大率及其可变性使用 66 个具有测量地震放大率(ETF 和 AF)的站点和 115 个具有 HVSR 曲线的站点进行量化。荷兰的场地响应(放大)分区图是通过将已发布的地质 3D 网格单元模型转换为五个类别而设计的,并且为大多数类别分配了 AF。这种在全国范围内进行的场址响应评估对于首次识别地震危险性增加的区域很重要,
更新日期:2021-08-26
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