Source parameters of large African earthquakes: implications for crustal rheology and regional kinematics
Source parameters of large African earthquakes: implications for crustal rheology and regional kinematics
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DOI：
10.1046/j.1365-246x.1998.00568.x
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发表时间：
1998-08
影响因子：
2.8
通讯作者：
A. Foster;J. Jackson
中科院分区：
文献类型：
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作者：
A. Foster;J. Jackson
利用模拟和数字波形的P和SH体波形反演确定了38次非洲地震的震源参数。该模型的结果与其他15个地震的震源参数也很好地约束体波形反演相结合。该数据集显示，东非部分地区的孕震厚度高达1.35公里，地震活动发生在整个上地壳和下地壳。一维热流计算表明，在太古代和元古代地壳35公里深处的温度为325-475 ° C，这要求下地壳具有干燥的镁铁质整体成分，以便产生地震变形。与这53个地震的滑动矢量相结合，从哈佛CMT目录的额外的28个解决方案，以调查板块运动学。在红海/亚喀巴湾，滑动矢量与Jestin、Huchon和Gaulier（1994）目前最佳板块模型预测的非洲-阿拉伯伸展方向非常一致。在南部东非裂谷系运动分为东南方向在赞比亚和东北方向在马拉加和鲁夸河，这联合收割机，以实现预测的非洲-索马里东西延伸。因此，Jestin等人（1994年）目前的最佳拟合板块模型充分描述了非洲的活跃运动学。
Summary Source parameters for 38 African earthquakes have been determined using P and SH body-waveform inversion of analogue and digital waveforms. The results of this modelling are combined with 15 other earthquakes whose source parameters are also well constrained by body-waveform inversion. This data set shows that parts of East Africa have a seismogenic thickness of up to ∼ 35 km, and that seismicity occurs throughout the upper and lower crust. 1-D heat-flow calculations suggest temperatures of ∼ 325–475 ° C at 35 km depth in the Archaean and Proterozoic crust, requiring that the lower crust has a dry, mafic bulk composition in order to deform seismogenically. The slip vectors associated with these 53 earthquakes are combined with an additional 28 solutions from the Harvard CMT catalogue in order to investigate plate kinematics. In the Red Sea/Gulf of Aqaba the slip vectors agree closely with the Africa–Arabia extension direction predicted by the current best-fit plate model of Jestin, Huchon & Gaulier (1994). In the southern East African Rift System motion is split between a southeast direction in Zambia and a northeast direction in Malaŵ i and Rukwa, which combine to achieve the predicted Africa–Somalia east–west extension. Thus the current best-fit plate model of Jestin et al. (1994) adequately describes the active kinematics of Africa.