北祁连-河西地区强震地点预测
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摘要
借助弹性块体边界负位错模型,获取了北祁连 河西地区1971～2000年5个时段地壳垂直运动反映的 构造块体及其边界断层运动、变形参量及构造梯度场的时空演化图像,高应变能积累部位和锁定能量强度。研究 了与门源Ms6.4、景泰Ms6.2、永登Ms5.8、景泰Ms5.9、玉门Ms5.9以及2003年10月25日民乐 山丹Ms6.1等 强震孕育有关的背景性前兆特征,初步建立了该区强震地点判定的定量依据:①在较大范围强烈隆起区内及其边 缘、梯度场高值区内及其边缘,尤其是与构造走向较为一致、隆起量5mm/a以上或梯度值8×10-8/a以上能达到 方圆50～100km甚至更大的区域;②强位错(3mm/a以上)锁定区段及其附近,较强负位错应力降或负位错地震 矩(分别为5×103Pa/a和5×1016Nm/a左右甚至更高)区段及其附近;或者显著加强段及其附近,可能发生6级左 右或6级以上地震。对应的异常越突出、项数越多、位置越重合,发震危险性越大。
By studied negative dislocation model of boundaries of elastic blocks,the movement and deformation parameters of the Northern Qilian-Hexi block and its boundaries and time-space evolution patterns of the tectionics gradient field,places of accumulation of high strain energy and intensity of locked energy as shown in the vertical movement in five phases from 1971 to 2000 are obtained,so are the background precursory features related to the generation of the strong earthquakes: Menyuan %M%s6.4, Jingtai %M%s6.2, Minle-Shandan %M%s6.1,etc. The quantitative bases for determining the locations where strong earthquakes will take place is summaried preliminarily as ① larger strongly uplifting region and its margins, region of gradient field and its margings, especially those regions uplifting over 5 mm/a of apophysis or with gradient of 8×10+{-8}/a and their area are 50～100 km (even more) diameter and being consistent with tectonic direction; ②The segment with higher dislocation (over 3 mm/a) and its adjacency; the segment with higher stress drop or seismic moment of negative dislocation (around 5×10+3 Pa/a or 5×10+{16}Nm/a, even more)and its neighborhood,or obvious enhanced segment and its adjacency where the earthquakes about or more than 6 magnitude may take place. The more outstanding are the anomalies, the more are the items of anomaly and the more consistent are the positions, the more possible is the occurrence of earthquakes.
By studied negative dislocation model of boundaries of elastic blocks,the movement and deformation parameters of the Northern Qilian-Hexi block and its boundaries and time-space evolution patterns of the tectionics gradient field,places of accumulation of high strain energy and intensity of locked energy as shown in the vertical movement in five phases from 1971 to 2000 are obtained,so are the background precursory features related to the generation of the strong earthquakes: Menyuan %M%s6.4, Jingtai %M%s6.2, Minle-Shandan %M%s6.1,etc. The quantitative bases for determining the locations where strong earthquakes will take place is summaried preliminarily as ① larger strongly uplifting region and its margins, region of gradient field and its margings, especially those regions uplifting over 5 mm/a of apophysis or with gradient of 8×10+{-8}/a and their area are 50～100 km (even more) diameter and being consistent with tectonic direction; ②The segment with higher dislocation (over 3 mm/a) and its adjacency; the segment with higher stress drop or seismic moment of negative dislocation (around 5×10+3 Pa/a or 5×10+{16}Nm/a, even more)and its neighborhood,or obvious enhanced segment and its adjacency where the earthquakes about or more than 6 magnitude may take place. The more outstanding are the anomalies, the more are the items of anomaly and the more consistent are the positions, the more possible is the occurrence of earthquakes.
引文
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6 张希,张四新,王双绪.昆仑8.1级地震前后地壳垂直运动的负位错模型[J].地震研究,2004,27(2):153～158.
6 ZhangXi,ZhangSixinandWangShuangxu.Negativedis locationmodelforverticalcrustalmovementbeforeandaf terKunlunMs8.1earthquake[J].J.ofSeismologicalRe search,2004,27(2):153-158.(inChinese)
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7 ZhangYongzhiandWangShuangxu.Thechangeoffractal dimensioninverticaldeformationduringseveralstrong earthquakesinHexiarea[J].InlandEarthquake,1993,7(3):257-263.(inChinese)
8 王庆良.河西祁连山地区近期形变场演化特征与孕震构造模式[J].地震,1994(3):64～71.
8 WangQingliang.Evolutionalcharacteristicsofrecentde formationfieldandseismogenictectonicmodelinHexiQilianshanarea[J],Earthquake,1994(3):64-71.(inChinese)
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9 CuiDuxin,JiangZaisenandWangShuangxu.Indexsystem decidingstrongearthquakeriskareabygeodeticdeforma tiondataandevolutionofverticaldeformationfieldinHexi region[J].NorthwesternSeismologicalJournal,1998,20(2):43-51.(inChinese)
10 张四新,江在森,王双绪,等.北祁连河西地区垂直形变场演化与地震活动关系研究[J].地壳形变与地震,2001,21(2):70～76.
10 ZhangSixin,JiangZaisen,WangShuangxu,etal.Study onevolutionoftheverticaldeformationfieldanditsrela tionshiptoseismicactivityinQilianMountainandHexiCorridor[J].CrustalDeformationandEarthquake,2001,21(2):70-76.(inChinese)
11 刘峡,黄立人,杨国华,等.北祁连河西走廊地区垂直形变与构造应力场的初步研究[J].地震地质,2003,25(2):307～316.
11 LiuXia,HuangLiren,YangGuohua,etal.Therelation shipbetweenverticaldeformationandtectonicstressfield inNorthQilianMountainHexiCorridorregion[J],Seis mologyandGeology,2003,25(2):307-316.(inChinese)
2 何玉梅,姚振兴.中国台湾南部及其周边岛屿现今地壳形变的位错模型[J].地球物理学报,2002,45(5):638～645.
2 HeYumeiandYaoZhenxing.Dislocationmodelforcur rentcrustaldeformationinandaroundsouthernTaiwan,China[J].ChineseJournalofGeophysics.2002,45(5):638-645.(inChinese)
3 高锡铭,伍吉仓.负位错模型与断层运动图像:确定滇西地震预报实验区的潜在震源区[J].地壳形变与地震,1994,14(4):1～8.
3 GaoXimingandWuJicang.Negativedislocationmodeland faultmovementpattern:determinationofpotentialregion inthestudiedareaofearthquakeprediction,westYunnan[J].CrustalDeformationandEarthquakes,1994,14(4):1-8.(inChinese)
4 张希,江在森,王琪,等.1999～2001年青藏块体东北缘地壳水平运动的非震反位错模型及变形分析[J].地震学报,2003,25(4):374～381.
4 ZhangXi,JiangZaisen,WangQi,etal.Aseismicnegative dislocationmodelanddeformationanalysisofcrustalhori zontalmovementduring1999-2001inthenortheastmar ginofQinghaiXizangblock[J].ActaSeismologicaSinica,2003,16(4):395-403.(inChinese)
5 张希,江在森,王琪,等.川滇地区近期地壳水平运动特征与强震关系研究[J].大地测量与地球动力学,2003,23(3):35～41.
5 ZhangXi,JiangZaisen,WangQi,etal.Recentcrustmo tionfeaturesinSichuanYunnanandtheirrelationshipto strongearthquakes[J].J.ofGeodesyandGeodynamics,2003,23(3):35-41.(inChinese)
6 张希,张四新,王双绪.昆仑8.1级地震前后地壳垂直运动的负位错模型[J].地震研究,2004,27(2):153～158.
6 ZhangXi,ZhangSixinandWangShuangxu.Negativedis locationmodelforverticalcrustalmovementbeforeandaf terKunlunMs8.1earthquake[J].J.ofSeismologicalRe search,2004,27(2):153-158.(inChinese)
7 张永志,王双绪.河西地区几次强震前的垂直地形变分维特征[J].内陆地震,1993,7(3):257～263.
7 ZhangYongzhiandWangShuangxu.Thechangeoffractal dimensioninverticaldeformationduringseveralstrong earthquakesinHexiarea[J].InlandEarthquake,1993,7(3):257-263.(inChinese)
8 王庆良.河西祁连山地区近期形变场演化特征与孕震构造模式[J].地震,1994(3):64～71.
8 WangQingliang.Evolutionalcharacteristicsofrecentde formationfieldandseismogenictectonicmodelinHexiQilianshanarea[J],Earthquake,1994(3):64-71.(inChinese)
9 崔笃信,江在森,王双绪.用大地形变判定强震危险区的指标体系及河西地区垂直形变场演化[J].西北地震学报,1998,20(2):43～51.
9 CuiDuxin,JiangZaisenandWangShuangxu.Indexsystem decidingstrongearthquakeriskareabygeodeticdeforma tiondataandevolutionofverticaldeformationfieldinHexi region[J].NorthwesternSeismologicalJournal,1998,20(2):43-51.(inChinese)
10 张四新,江在森,王双绪,等.北祁连河西地区垂直形变场演化与地震活动关系研究[J].地壳形变与地震,2001,21(2):70～76.
10 ZhangSixin,JiangZaisen,WangShuangxu,etal.Study onevolutionoftheverticaldeformationfieldanditsrela tionshiptoseismicactivityinQilianMountainandHexiCorridor[J].CrustalDeformationandEarthquake,2001,21(2):70-76.(inChinese)
11 刘峡,黄立人,杨国华,等.北祁连河西走廊地区垂直形变与构造应力场的初步研究[J].地震地质,2003,25(2):307～316.
11 LiuXia,HuangLiren,YangGuohua,etal.Therelation shipbetweenverticaldeformationandtectonicstressfield inNorthQilianMountainHexiCorridorregion[J],Seis mologyandGeology,2003,25(2):307-316.(inChinese)
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