1303年洪洞地震宏观震中修订的新证据

NEW EVIDENCES FOR AMENDMENT OF MACRO-EPICENTER LOCATION OF 1303AD HONGTONG EARTHQUAKE

1303年9月25日的洪洞地震为依据文献资料确定的中国大陆内部第一个M8. 0地震,因其宏观震中与1695年临汾地震的宏观震中仅相距40km,且2者仅间隔392a而受到持续关注。文中对历史文献进行重新梳理并对震中区同震次生灾害进行系统解译研究,所得结果表明:1) 1303年洪洞地震的极震区包括临汾盆地,也包括太原盆地南部与灵石凸起,后者范围内严重破坏的建筑物的记载数量与临汾盆地相当,说明太原盆地南部与灵石凸起和临汾盆地一样在洪洞地震中遭遇同等或更加严重的破坏,而1695年临汾地震的极震区仅局限在临汾盆地内,且极震区位于洪洞以南; 2)位于灵石凸起上的1. 1万个黄土地震滑坡由1303年洪洞地震触发,基于文献震害记录和地震次生灾害的集中分布特征,建议将1303年洪洞地震的宏观震中从之前的洪洞附近(36. 3°N,111. 7°E)向北移动约60km,这样可以较合理地解释密集黄土地震滑坡与宏观震中的空间对应关系,新的宏观震中(36. 8°N,111. 7°E)位于霍州与灵石之间,同震滑坡加剧了极震区灾情的严重程度; 3)文中为重新认识山西地堑系中部2次重要历史强震的关系提供了新的证据和研究思路。

The Hongtong earthquake occurring on 25 September 1303 in both Linfen Basin(LFB)and Taiyuan Basin(TYB)in Shanxi Graben is the first M 8.0 earthquake based on the Chinese literature in China mainland,392 years later,the Linfen M 7.5 earthquake occurred on 18 May 1695 in Linfen Basin with its macro-epicenter distance of only 40km south of the Hongtong earthquake.Due to their close macro-epicenter distance and shortly interval of 392a,it attracted continuous attention to the geoscientists around Southern Shanxi Graben,southeastern Orods Plate.This paper combines the historical documents and interpreting the coseismic triggered disasters in study area.The results show that:1)the number of building damaged in the southern TYB and Lingshi Uplift(LSU)during 1303 Hongtong earthquake is similar to that of the LFB,indicating that the TYB and LSU maybe suffered the same or even worse earthquake disaster losses during the 1303 Hongtong earthquake.While the 1695 Linfen earthquake is confined within the LFB and south of Hongtong County;2)More than 11￣￣000 loess landslides were triggered by the 1303 Hongtong earthquake event between LFB and TYB,which is consistent with the literature records.We suggested the macro-epicenter of the 1303 Hongtong earthquake should move about 60km northward from the present location(36.3°N,111.7°E)near Hongtong County to the new location(36.8°N,111.7°E)between Huozhou City and Lingshi County,the new macro-epicenter location can reasonably explain the large-scale centralized earthquake-triggered landslides during the event.The landslides had aggravated the severity of the loss;3)Our result helps to understand the spatial distribution of the two strong earthquakes and the relationship between them,especially the distribution map of earthquake-induced loess landslides by 1303 Hongtong earthquake extracted using the Google Earth images,which supports the amendment of the macro-epicenter.