地震研究

1936年甘肃康乐63/4级地震地表破裂带调查^*

(1.中国地震局兰州地震研究所,甘肃兰州 730000; 2.中国地震局地震预测研究所兰州科技创新基地,甘肃兰州 730000; 3.安徽省地震局,安徽合肥 230031; 4.内蒙古有色地质勘查局,内蒙古自治区呼和浩特 010010)

关键词：地表破裂带; 1936年康乐63/4级地震; 同震位移; 基岩崩塌

Surveys on Surface Rupture Phenomena of Gansu Kangle M63/4 Earthquake in 1936

ZHANG Bo^1,2,HE Wen-gui^1,2,FANG Liang-hao³,PANG Wei^1,2,ZHAO Ze-xian⁴,LIU Xing-wang^1,2

(1. Lanzhou Institute of Seismology,CEA,Lanzhou 730000,Gansu,China)(2. Lanzhou Technology Innovation Base,Institute of Earthquake Science,CEA,Lanzhou 730000,Gansu,China)(3. Earthquake Administration of Anhui Province,Hefei 230031,Anhui,China)(4. Inner Mon

Keywords：surface rupture belt; Kangle M63/4 earthquake in 1936; cosismic displacement; bedrock falls

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参考文献

结合前人研究结果和野外考察,发现1936年甘肃康乐63/4级地震的地表破裂带长14 km,走向NWW,主要由3小段(西段、中段和东段)呈右阶排列而成。地表破裂主要有地震陡坎、地裂缝等。西段长3.7 km,有新鲜的崩塌堆积; 中段长4.4 km,有大规模的基岩崩塌,同震左旋位移和垂直位移分别为2.5 m和0.6 m; 东段长约6 km,同震水平位移和垂直位移分别为1.5 m和0.3 m。同震变形以左旋走滑为主,兼具逆冲分量,最大地表垂直位错量(0.6 m)仅为水平位错量(2.5 m)的1/4。1936年康乐地震时崩落的岩块上零星生长着最大直径仅20～30 mm的丽石黄衣,部分无地衣生长,此次地震由围子山—大夏河断裂向东扩张所致。

Combined with the previous studies and the field surveys of Kangle M63/4 earthquake in 1936,we found that the length of surface rupture is about 14 km,the strikes of it is NWW. The surface rupture is mainly constituted of 3 segments(the western,the middle and the eastern segements)and exhibits a right-stepping arranging,and the rupture phenomena in extreme seismic zone are mainly earthquake scarp and ground fissures etc.. The western segment where the fresh rock falls accumulated extends about 3.7 km; the middle segment where huge scale rock falls extends about 4.4 km,the coseismic left-lateral and uplift displacements in the middle segment is 2.5 m and 0.6 m respectively; the eastern segment extends about 6 km,and the coseismic horizontal and uplift offsets is 1.5 m and 0.3 m respectively. The coseismic deformation caused by the earthquake is mainly left-lateral with thrust components,the maximum surface uplift dislocation(0.6m)is one-fourth of horizonal component(2.5m). The falling rocks caused by Kangle M63/4 earthquake in 1936 have scattered distributed Xanthoria elegans with a maximum diameter about 20～30 mm,some falling rock without any lichens. The Kangle M63/4 earthquake is caused by the eastern-extension activity of Weizishan-Daxiahe Fault.

引言
1 地震构造背景分析
2 地震地表破裂带特征
3 地震次生灾害——基岩崩塌
4 发震构造特征
5 结论

图1 青藏高原东北缘地形特征与主要活动构造(底图来源于SRTM3,分辨率为90 m)(a),西秦岭北缘断裂西段地形特征与几何展布(底图来源于ASTER GDEM,垂直分辨率20 m,水平分辨率30 m)(b)及其附近岩浆岩和上新世—全新世地层分布特征(c)<br/>Fig.1 Topographic characteristic and main active tectonics in northeast margin of Qinghai-Tibet Plateau(base map is from SRTM3 data,the resolution is 90 m)(a),the topographic characteristics and geometric distribution of the western segment of northern margin of west Qinling Fault(base map is from ASTER GDEM data,vertical and horizontal resolution is 20 m and 30 m respectively)(b)and the magmatic rocks and stratigraphy distribution from Pliocene to Holocene(c)around the fanlt

图1 青藏高原东北缘地形特征与主要活动构造(底图来源于SRTM3,分辨率为90 m)(a),西秦岭北缘断裂西段地形特征与几何展布(底图来源于ASTER GDEM,垂直分辨率20 m,水平分辨率30 m)(b)及其附近岩浆岩和上新世—全新世地层分布特征(c)
Fig.1 Topographic characteristic and main active tectonics in northeast margin of Qinghai-Tibet Plateau(base map is from SRTM3 data,the resolution is 90 m)(a),the topographic characteristics and geometric distribution of the western segment of northern margin of west Qinling Fault(base map is from ASTER GDEM data,vertical and horizontal resolution is 20 m and 30 m respectively)(b)and the magmatic rocks and stratigraphy distribution from Pliocene to Holocene(c)around the fanlt

图2 1936年甘肃康乐63/4级地震等震线和极震区范围(a)及极震区地表<br/>破裂现象及分布特征(b)国家地震局兰州地震研究所.1993.西秦岭北缘断裂带1:5万活动断裂地质图说明书.<br/>Fig.1 The range of isoseismal lines and meizoseismal area(a)and surface rupture phenomena and its distribution characteristic in meizoseismal area(b)of Gansu Kangle M63/4 earthquake in 1936①

图2 1936年甘肃康乐63/4级地震等震线和极震区范围(a)及极震区地表
破裂现象及分布特征(b)国家地震局兰州地震研究所.1993.西秦岭北缘断裂带1:5万活动断裂地质图说明书.
Fig.1 The range of isoseismal lines and meizoseismal area(a)and surface rupture phenomena and its distribution characteristic in meizoseismal area(b)of Gansu Kangle M63/4 earthquake in 1936①

图3 极震区范围及地表破裂现象<br/>Fig.3 The range of extreme seismic zone and its surface rupture phenomena of Gansu Kangle M63/4 earthquake in 1936

图3 极震区范围及地表破裂现象
Fig.3 The range of extreme seismic zone and its surface rupture phenomena of Gansu Kangle M63/4 earthquake in 1936

图4 地表破裂带中段地表破裂现象<br/>(a)部分充填的地震裂缝(镜向E);(b)高3.5 m的正向陡坎(镜向N);(c)山坡上断层地貌(镜向NW);(d)观察<br/>点P1处冲沟左旋及最新地震陡坎(镜向N);(e)1936年康乐M63/4地震形成的高60 cm的新鲜陡坎(镜向N)<br/>Fig.4 Surface rupture phenomenoa in the middle segment of surface rupture belt(a)earthquake fissures partly filled with deluvium(mirror at E);(b)normal fault scarp with a height of 3.5 m(mirror at N); (c)landform of fault extends through the mountain slope(mirror at NW);(d)left-lateral gullies and most recent earthquake scarp at P1 observation point(mirror at N);(e)a 60 cm high scarp caused by Kangle M63/4 earthquake in 1936(mirror at N)

图4 地表破裂带中段地表破裂现象
(a)部分充填的地震裂缝(镜向E);(b)高3.5 m的正向陡坎(镜向N);(c)山坡上断层地貌(镜向NW);(d)观察
点P1处冲沟左旋及最新地震陡坎(镜向N);(e)1936年康乐M63/4地震形成的高60 cm的新鲜陡坎(镜向N)
Fig.4 Surface rupture phenomenoa in the middle segment of surface rupture belt(a)earthquake fissures partly filled with deluvium(mirror at E);(b)normal fault scarp with a height of 3.5 m(mirror at N); (c)landform of fault extends through the mountain slope(mirror at NW);(d)left-lateral gullies and most recent earthquake scarp at P1 observation point(mirror at N);(e)a 60 cm high scarp caused by Kangle M63/4 earthquake in 1936(mirror at N)

表1 中国西部地区走滑断裂震级—地表破裂参数经验关系<br/>Tab.1 Empirical relationships between magnitude and surface rupture parameters for strike-slip faults in western China

表1 中国西部地区走滑断裂震级—地表破裂参数经验关系
Tab.1 Empirical relationships between magnitude and surface rupture parameters for strike-slip faults in western China

图5 地震破裂带东段地表破裂现象(a)高20～50 m的断层崖(镜向NW);(b)观察点P2处的剖面;(c)观察点P3处冲沟左旋位错1.5 m和7 m(镜向S);(d)1936年康乐地震形成的30 cm高的新鲜陡坎(镜向W);(e)图5d的几何分析
Fig.5 Surface ruptures phenomena in eastern segment of surface rupture belt(a)fault scarp of 20～50 m(mirror at NW);(b)fault profile at P2 observation point;(c)left-lateral offset of gullies of 1.5 m and 7 m at P3 observation point(mirror at S);(d)a scarp of 30 cm caused by Kangle M63/4 earthquake in 1936(mirror at W);(e)geometrical analysis of Fig.5d

图6 1936年康乐地震造成的基岩崩塌(a)热德纳山下基岩断层崖及崩塌堆积物(镜向NE);(b)最新崩塌堆积物(镜向NW); (c)高大的基岩断层崖和崖底崩积物(镜向NE)<br/>Fig.6 Bedrock falls caused by Kangle M63/4 earthquake in 1936(a)bedrock fault scarp and distribution of colluvial deposit under the Redena Moutain(mirror at NE);(b)the newest colluvial deposits(mirror at NW);(c)huge scale bedrock fault cliff and colluvial deposits under it(mirror at NE)

图6 1936年康乐地震造成的基岩崩塌(a)热德纳山下基岩断层崖及崩塌堆积物(镜向NE);(b)最新崩塌堆积物(镜向NW); (c)高大的基岩断层崖和崖底崩积物(镜向NE)
Fig.6 Bedrock falls caused by Kangle M63/4 earthquake in 1936(a)bedrock fault scarp and distribution of colluvial deposit under the Redena Moutain(mirror at NE);(b)the newest colluvial deposits(mirror at NW);(c)huge scale bedrock fault cliff and colluvial deposits under it(mirror at NE)

图7 崩积物上生长的地衣<br/>(a)1936年地震崩积物上生长最大直径为20～30 mm的丽石黄衣,早期地震崩积物上密集生长的<br/>墨绿色地衣和白色死地衣(b)及密集成片的丽石黄衣(c)<br/>Fig.7 Lichens of different kinds and diameter growed on rock falls(a)Xanthoria elegans with the maximum diameter of 20～30 mm growed on the colluvial deposits caused by Kangle M63/4earthquake in 1936; the blackish green lichens and white dead lichens(b)and Xanthoria(c)grow densely elegans on the colluvial deposits caused by earlier earthquakes

图7 崩积物上生长的地衣
(a)1936年地震崩积物上生长最大直径为20～30 mm的丽石黄衣,早期地震崩积物上密集生长的
墨绿色地衣和白色死地衣(b)及密集成片的丽石黄衣(c)
Fig.7 Lichens of different kinds and diameter growed on rock falls(a)Xanthoria elegans with the maximum diameter of 20～30 mm growed on the colluvial deposits caused by Kangle M63/4earthquake in 1936; the blackish green lichens and white dead lichens(b)and Xanthoria(c)grow densely elegans on the colluvial deposits caused by earlier earthquakes