Daxer Christoph, Huang Jyh-Jaan Steven, Weginger Stefan, Hilbe Michael, Strasser Michael, Moernaut Jasper
Institute of Geology, University of Innsbruck, Innrain 52f, 6020, Innsbruck, Austria.
Institute of Oceanography, National Taiwan University, Taipei, Taiwan.
Sci Rep. 2022 Nov 19;12(1):19943. doi: 10.1038/s41598-022-24487-w.
Seismic hazard maps are crucial for earthquake mitigation and mostly rely on probabilistic seismic hazard analysis (PSHA). However, the practise and value of PSHA are under debate because objective testing procedures for seismic hazard maps are scarce. We present a lacustrine turbidite record revealing 44 earthquakes over the last ~ 14 ka and use it to test seismic hazard curves in southern Austria. We derive local seismic intensities for paleo-earthquakes by applying scaling relationships between the sedimentary imprint and seismic intensity of well-documented historical earthquakes. The last ~ 2.8 ka of the record agree with a Poissonian recurrence behaviour and therefore a constant hazard rate, which is the modelling choice for standard PSHA. The lacustrine data are consistent with the intensity-frequency relationship of the local seismic hazard curve, confirming the current PSHA approach for this part of Austria. On longer timescales, distinct phases of enhanced regional seismicity occurred, indicating a potential increase of seismic hazard after large earthquakes-a factor hitherto disregarded in the PSHA of the Eastern Alps. Our new method forms an independent procedure to test hazard maps in any setting where suitable lake systems are available.
地震危险性地图对于减轻地震灾害至关重要，并且主要依赖概率地震危险性分析（PSHA）。然而，由于缺乏用于地震危险性地图的客观测试程序，PSHA的实践和价值一直存在争议。我们展示了一个湖相浊积岩记录，揭示了过去约14000年里的44次地震，并利用它来测试奥地利南部的地震危险性曲线。我们通过应用沉积印记与记录完备的历史地震的地震烈度之间的比例关系，得出古地震的当地地震烈度。该记录的最后约2800年符合泊松复发行为，因此具有恒定的危险率，这是标准PSHA的建模选择。湖相数据与当地地震危险性曲线的烈度-频率关系一致，证实了奥地利这一地区目前的PSHA方法。在更长的时间尺度上，出现了区域地震活动增强的不同阶段，这表明大地震后地震危险性可能增加——这是迄今为止东阿尔卑斯山PSHA中被忽视的一个因素。我们的新方法形成了一个独立的程序，用于在有合适湖泊系统的任何环境中测试危险性地图。
