澜沧江流域水电工程地区的环境剪应力及震源参数
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摘要
使用昆明数字地震台网记录的地震波形资料,研究了1999年1月至2003年12月澜沧江流域地区的震源参数和环境应力τ0值,重点讨论了小湾、漫湾和大朝山三个电站高坝水库地区的应力状态及震源参数,结果表明地面运动峰值速度(r·v)符合M1/20τ0的标度关系,较适合澜沧江流域地区中小地震活动规律;水利枢纽工程地区的环境剪应力τ0平均值为36MPa,明显低于澜沧江流域北东和南西地区,属于低应力地区;发生于该区的地震震源深度多小于10km,震级大部分小于3级。分析认为发生于该区的低应力、浅源、低强度地震,可能与该区库区蓄水压力增加有关。
Using the data recorded by the Kunming Digital Seismic Network, the source parameters and ambient stress τ_0 along the Lancangjiang River valley from January of 1999 to December of 2003 are studied. The stress state and source parameters in the Xiaowan,Manwan and Dachaoshan reservoir regions are discussed on emphases. The results show that the peak value velocity (r·v) of ground motion is accorded with the scale relation of M~1/2 _0τ_0, which is suitable to the seismicity pattern along the Lancangjiang River valley. The mean value of the ambient shear stress τ_0 in the key engineering of water conservancy is 3.6 MPa, which is obviously lower than that in NE and SW parts of the Lancangjiang River valley,belonging to the areas of low stress. Most of the source depths in this region are less than 10 km and most of the magnitudes are less than 3.0. It is considered after analysis that the low stress, shallow source depth and low magnitude in this region are possibly related to the increase of the pressure from water storage.
Using the data recorded by the Kunming Digital Seismic Network, the source parameters and ambient stress τ_0 along the Lancangjiang River valley from January of 1999 to December of 2003 are studied. The stress state and source parameters in the Xiaowan,Manwan and Dachaoshan reservoir regions are discussed on emphases. The results show that the peak value velocity (r·v) of ground motion is accorded with the scale relation of M~1/2 _0τ_0, which is suitable to the seismicity pattern along the Lancangjiang River valley. The mean value of the ambient shear stress τ_0 in the key engineering of water conservancy is 3.6 MPa, which is obviously lower than that in NE and SW parts of the Lancangjiang River valley,belonging to the areas of low stress. Most of the source depths in this region are less than 10 km and most of the magnitudes are less than 3.0. It is considered after analysis that the low stress, shallow source depth and low magnitude in this region are possibly related to the increase of the pressure from water storage.
引文
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[5]陈培善,DudaSJ .峰值速度和加速度对环境应力的依赖性[J].地球物理学报,1993,36(2):185-194.
[6]秦嘉政,邬成栋,钱晓东.2001年永胜M60余震序列的地震应力降[J].地震研究,2004,27(2):146-152.
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