冰岛全国范围的频率相关地震场地放大模型
Nationwide frequency-dependent seismic site amplification models for Iceland
AI总结：
本研究针对冰岛缺乏本地频率相关地震场地效应研究的问题，构建了基于本地地质单元的全国场地放大模型，证实其性能优于国际通用大规模模型，为冰岛地震危险性评估提供了可靠依据。
摘要：
由局部场地条件导致的地震波放大是区域地震危险性评估的重要方面。由于缺乏对冰岛强震期间频率相关场地效应的系统研究，冰岛一直沿用其他地震区大规模研究中使用的各类局部场地代理指标。近期，研究人员首次对冰岛西南部34个台站的地震场地效应进行了严格量化，并将其与冰岛不同的地质单元（硬岩、岩石、熔岩和沉积土）建立了关联。这些地质单元在冰岛全境广泛分布，因此本文提出：1）可助力更准确估算场地效应的全国范围代理指标（坡度、Vs30、地质单元）地图，以及相关的2）冰岛频率相关场地放大地图。文中给出了各大地质单元在1-30 Hz频段及峰值地面加速度（PGA）下的频率相关场地系数。最后，我们基于其他地震区开发的最新大规模模型（ESRM20）及其采用的各类场地代理指标（基于地质和坡度推断的Vs30、地貌沉积厚度）生成了场地放大地图。我们对比了冰岛本地模型与非冰岛的大规模模型的场地代理指标地图和放大地图。非冰岛大规模研究的代理指标地图和放大地图，无论是空间分布模式还是放大水平，都与本研究呈现的本地定量强震研究观测结果不相符。我们认为这一差异主要源于冰岛年轻的地质条件及其形成历史。此外，我们通过评估模型预测值相对于冰岛南部地震带经验场地放大的偏差，对比了不同频率下的模型性能，残差的台站间变异性分析表明本地放大模型的性能更优。
英文摘要：
Seismic wave amplification due to localized site conditions is an important aspect of regional seismic hazard assessment. Without systematic studies of frequency-dependent site-effects during strong Icelandic earthquakes, various local site proxies of large-scale studies in other seismic regions have been used in Iceland. Recently, earthquake site-effects were rigorously quantified for 34 stations in Southwest Iceland for the first time and correlated to distinct Icelandic geological units of hard rock, rock, lava rock, and sedimentary soil. These units are prevalent throughout Iceland and herein we present 1) nationwide maps of proxies (slope, Vs30, geological units) that may contribute to a better estimation of site effects and associated, 2) frequency-dependent site-amplification maps of Iceland. The frequency-dependent site factors for each geological unit are presented at 1-30 Hz and PGA. Finally, we generate site amplification maps based on recent large-scale models developed in other seismic regions (ESRM20) and various site proxies they are based on (geology- and slope-based inferred Vs30, geomorphological sedimentary thickness). We compare site-proxy maps and amplification maps from both Icelandic and large-scale, non-Icelandic, models. Neither spatial patterns nor amplification levels in either proxy or amplification maps from large-scale non-Icelandic studies resemble those observed from local quantitative strong-motion research as presented in this study. We attribute the discrepancy primarily to the young geology of Iceland and its formation history. Additionally, we compare model performance across frequencies by assessing the bias of model predictions against empirical site amplifications in the South Iceland Seismic Zone, accounting for site-to-site variability of residuals indicating the superior performance of the local amplification model.
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