Vietnam has a low-to-moderate seismicity, but the currently available strong ground motion data used as a basis for a seismic-resistant design are insufficient. Generally, to overcome this issue, strong ground motions recorded at other places around the world are used, which have similar seismic, tectonic and physical earthquake characteristics, such as earthquake magnitude, source model, distance to the source, tectonic geological conditions, and soil conditions. However due to different path effects and site effect, if applied to the site-specific studies in Vietnam, the above approach would generate certain errors. Therefore, it is important to obtain strong ground motion data that are applicable for seismic design of constructions in a particular region. Especially, it is important to adhere to strict seismic design requirements for facilities, such as hydropower, thermal, and nuclear power plants. One of the most interesting solutions is the theory of simulating the waveforms of strong earthquakes commonly known as the empirical Green’s function. The empirical Green’s function is a useful tool for estimating the ground motions produced by large earthquakes using small earthquake records. The basic idea of the method is that these small events data already incorporate the information of the propagation path and the local site effects. Ground-motion simulations essentially use these small events as an empirical Green’s function and add them following the scaling law based on the omega-square model. In this article, we simulate design basis ground motion for the Song Tranh 2 hydropower dam as an example. We have applied the empirical Green’s function method to predict broadband ground-motion time histories for several M5.5, one M5.7, and one M5.9 earthquake scenarios at the dam site based on M4.6 observed ground motions without/with considering radiation pattern corrections. The results confirm that strong ground-motion simulations are applicable to seismic hazard assessment in Vietnam. Once we obtain accurate source parameters, the site-specific synthetic ground motions of the earthquake scenarios can be used for seismic design safety in Vietnam.

中文翻译：

---

越南特定地点地面运动预测的经验格林函数模拟

越南具有中低地震活动性，但目前用作抗震设计基础的强地震动数据不足。通常，为了克服这个问题，使用在世界其他地方记录的强地震动，它们具有相似的地震、构造和物理地震特征，例如震级、震源模式、距震源的距离、构造地质条件和土壤使适应。但由于路径效应和场地效应不同，如果应用于越南的特定场地研究，上述方法会产生一定的误差。因此，获取适用于特定区域建筑抗震设计的强地震动数据非常重要。特别是，必须遵守严格的设施抗震设计要求，如水电、火力和核电站。最有趣的解决方案之一是模拟强地震波形的理论，通常称为经验格林函数。经验格林函数是一种有用的工具，可用于使用小地震记录估计大地震产生的地面运动。该方法的基本思想是这些小事件数据已经包含了传播路径和本地站点效应的信息。地面运动模拟本质上使用这些小事件作为经验格林函数，并按照基于欧米茄平方模型的标度定律添加它们。在本文中，我们以 Song Tranh 2 水电站大坝的设计基准地震动为例进行了模拟。我们已经应用经验格林函数方法，基于 M4.6 观测到的地面运动，在没有/有考虑的情况下预测大坝站点的几个 M5.5、一个 M5.7 和一个 M5.9 地震情景的宽带地震动时间历程辐射模式校正。结果证实，强地面运动模拟适用于越南的地震危险性评估。一旦我们获得了准确的震源参数，地震场景中特定地点的合成地面运动就可以用于越南的抗震设计安全。