Strong historical earthquakes and their relationships with the Tan-Lu fault system and modern seismicity in eastern China
Strong historical earthquakes and their relationships with the Tan-Lu fault system and modern seismicity in eastern China
复制标题
DOI：
10.1007/s11069-022-05565-8
复制
发表时间：
2022-08
期刊：
影响因子：
3.7
通讯作者：
Jian Wang;I. Main
中科院分区：
文献类型：
--
作者：
Jian Wang;I. Main
中国东部最大的地震（8.5级）发生在1668年的郯城附近。该地区历史上曾发生6次以上地震。我们重新检查了该地区的原始历史档案，添加了独立的约束条件，如活动断层图、当地地形、中国的强度衰减规律以及存档数据的相关行政实践，以重新评估震源参数（震中、震级或最大强度）。我们使用地震密度指数——一种对震源震级加权的地震活动聚类的测量——来确定当前地震活动聚类的候选带，这些候选带可能代表了板内环境中过去历史事件的长期记忆。我们为七个事件中的四个更新至少一个源参数。1668-1672Ms8 / 2郯城地震序列的主震和两次余震位于郯庐断裂带走向，每次地震都伴有显著的连续地震密度异常，其椭圆轮廓沿其走向拉长。在这个序列中，第三次主要余震（Ms≈6）位于离断裂带约200公里的地方。7个历史事件中有6个具有不能用现代地震活动余震解释的地震密度异常（ML≤5.3），因此是长寿命余震序列的候选带。宿迁以南郯庐断裂带段地震密度未见明显异常，但在公元前6280年左右有ams8.5地震的古地震证据，为该地区大地震的长期记忆提供了上限。
The largest earthquake(Ms8½) in eastern China occurred near Tancheng in 1668. SixM≥ 6 earthquakes occurred in this region in historical time. We re-examine the primary historical archives from this region, adding independent constraints such as maps of active faults, local topography, intensity attenuation laws for China, and relevant administrative practices in archiving data, to reassess source parameters (epicenter, magnitude, or maximum intensity). We use the seismic density index—a measure of the clustering of seismicity weighted by source magnitude—to identify candidate zones of present-day clustering of seismicity than may represent a long-term memory of past historical events in an intraplate setting. We update at least one of the source parameters for four of the seven events. The main shock and two aftershocks of the 1668–1672Ms8½ Tancheng earthquake sequence locate along the strike of the Tan-Lu fault zone, each associated with significant and contiguous seismic density anomalies whose elliptical contours are elongated along its strike. A third major aftershock (Ms≈ 6) in this sequence locates some 200 km away from the fault zone. Six of the seven historical events have seismic density anomalies that cannot be explained by aftershocks of modern seismicity (ML≤ 5.3), and hence are candidate zones for long-lived aftershock sequences. In contrast, there are no significant seismic density anomalies along the section of Tan-Lu fault south of Suqian, despite palaeo-seismic evidence for aMs8½ earthquake around 6280 B.C., providing an upper bound to long-term memory of great earthquakes in this region.