地震研究

据历史资料记载,云南宜良地区曾于公元1500年发生过一次M>7地震,该地震发生在小江断裂带上,但对其具体发震断层及其地表破裂分布的确定,仍存有较大分歧。在高分辨率遥感影像解译基础上,沿宜良盆地西缘断裂进行了翔实的地质地貌调查,获得了该断裂晚第四纪活动的一些地质地貌证据。店房探槽和打挂村探槽组开挖结果揭示:宜良盆地西缘断裂断错了全新世地层,最新一次活动断错了(2 460±30)a BP的地层。结合断错地貌和地震破坏记录的分析,其最新事件可能对应于1500年宜良地震。

The Xiaojiang Fault Zone forms the southeastern boundary of the Sichuan-Yunnan Block.As one of the most seismically active zones in Yunnan Province,many historical strong earthquakes(M>7),such as the 1833 M8 Songming earthquake,occurred in it.Along the western margin of the Yiliang Basin and in the eastern branch of the Xiaojiang Fault Zone,there is a secondary fault zone which is composed of the Xiaoxinjie-Yiliang Fault,the Yiliang-Xujiadu Fault,and the Majie-Nanyangjie Fault.The M>7 Yiliang earthquake in 1500 had produced a long surface rupture distributing discontinuously along the western margin of the Yiliang Basin.The remote sensing image shows that the secondary fault zone has a remarkable linear feature.There are a lot of dislocation landforms such as fault trough and fault scarps along its strike.Based on interpretation of high-resolution remote sensing images,and through detailed geological and geomorphological investigation,we obtained geological evidences of the late Quaternary activity of the secondary fault.The trench in Dianfang village revealed that the secondary fault had dislocated the Holocene stratum and behaved as a normal fault.Two trenches in Dagua village reveal that the 2460 a BP strata had been dislocated by the fault along the western margin of the Yiliang Basin.We analyzed dislocation landform and the historical recordings,and found that the Yiliang earthquake in 1500 may be the latest event.

引言
1 研究背景
2 宜良盆地西缘断裂晚第四纪活动的地表形迹
3 探槽剖面特征
4 讨论
5 结论

图1 小江断裂带及周边活动断裂构造背景与M≥6.0历史地震分布<br/>Fig.1 Tectonic background of the active faults and M≥6.0 earthquakes in the Xiaojiang Fault Zone and its vicinity

图1 小江断裂带及周边活动断裂构造背景与M≥6.0历史地震分布
Fig.1 Tectonic background of the active faults and M≥6.0 earthquakes in the Xiaojiang Fault Zone and its vicinity

图2 宜良盆地西缘断裂几何展布(a),店房断错地貌(b),分水岭至下米户一带断层陡坎与水系位错(c)及柏子村西侧水系左旋位错(d)<br/>Fig.2 Geometric distribution of the fault along the western margin of the Yiliang Basin(a),offset landforms of Dianfang(b),fault scarps and offset streams from Fenshuiling village to Xiamihu village(c),and left-laterally offset streams in Bozicun village(d)

图2 宜良盆地西缘断裂几何展布(a),店房断错地貌(b),分水岭至下米户一带断层陡坎与水系位错(c)及柏子村西侧水系左旋位错(d)
Fig.2 Geometric distribution of the fault along the western margin of the Yiliang Basin(a),offset landforms of Dianfang(b),fault scarps and offset streams from Fenshuiling village to Xiamihu village(c),and left-laterally offset streams in Bozicun village(d)

图3 七江村至腊介村断错地貌<br/>Fig.3 Offset landforms from Qijiang village to Lajie village

图3 七江村至腊介村断错地貌
Fig.3 Offset landforms from Qijiang village to Lajie village

图4 宜良盆地西缘断裂断层剖面及地质解译图
Fig.4 Fault profile along the western margin of the Yiliang Basin:geological profile and interpretation in Fenshuiling village(a),Shiba village(b),Lajie village(c),and Qijiang village(d)

图5 店房探槽南壁剖面拼接图(a)及地质解译图(b)<br/>Fig.5 Collage photographs(a)and geological section(b)of the southern wall of Trench Dianfang

图5 店房探槽南壁剖面拼接图(a)及地质解译图(b)
Fig.5 Collage photographs(a)and geological section(b)of the southern wall of Trench Dianfang

图6 打挂村探槽全貌<br/>Fig.6 A field photo showing the location of two trenches in Daguacun village

图6 打挂村探槽全貌
Fig.6 A field photo showing the location of two trenches in Daguacun village

图7 打挂村探槽TC1北壁剖面拼接图(a)及地质解译图(b)<br/>Fig.7 Collage photographs(a)and geological section(b)of the northern wall of trench Daguacun

图7 打挂村探槽TC1北壁剖面拼接图(a)及地质解译图(b)
Fig.7 Collage photographs(a)and geological section(b)of the northern wall of trench Daguacun

图8 打挂村探槽TC2南壁剖面拼接图(a)及地质解译图(b)<br/>Fig.8 Collage Photographs(a)and geological section(b)of the southern wall of Trench Daguacun

图8 打挂村探槽TC2南壁剖面拼接图(a)及地质解译图(b)
Fig.8 Collage Photographs(a)and geological section(b)of the southern wall of Trench Daguacun

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备注

引言

1 研究背景

2 宜良盆地西缘断裂晚第四纪活动的地表形迹

3 探槽剖面特征

4 讨论

5 结论

期刊信息