台湾恒春海外地震的P波震相特征分析与探讨
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摘要
本文分析了台湾恒春海外的一次地震的记录波形的P波的主要特征。首先对其首波PN进行分析 ,结果表明其线性关系较好 ,计算出的速度值与华南地区近震走时表中所用的地壳模型中的速度值一致。其次对其PN波的续至波进行分析 ,发现该处的地震其射线穿过台湾岛后的地震记录波形明显与没有穿过台湾岛的不同 ,即没有穿过台湾岛的地震记录波形中首波震相之后明显存在有另一组震相 ,而穿过台湾岛后的地震记录波形则没有或不明显。该组震相最明显特征是它与首波的到时差随震中距的加大而减小 ,据此 ,作者认为它可能是一组波 ,即地壳内的双程反射波 ,表明该处有低速层存在。分析结果表明 ,台湾海峡南部即福建省的东山海外地区及泉州、漳州、永安地区的下方有一低速层存在。
This paper analyze mostly the character of P-wave in one earthquake in the overseas of Henchun Taiwan(O∶2003-2-8,15∶21,MS 5.2,n-lat∶21.1o,e-lon:121.44o).First,we analyze the head wave PN, it shows that it's good in linearity relation,and the value of PN velocity counted out is same to the crust model using in the list of pass time of HuaNan seism.Then we analyze the succedent wave,found that the wave recorded exist evidence different phenomenon whether the earthquake radial traverse the island of Taiwan, that it will be recorded a other phase after the head wave when the radial does not traverse the island of Taiwan,and it will do not exist or not evidence when the radial traverses the island of Taiwan.The evidence character in this succedent wave phase is that the gap of arrive-time to the head wave would minish by the increase of distance of epicenter.According this,the author thinks it may be the wave of,it is the reflect wave of double-range in the earth's crust.And it will show the existing of the low velocity layer.The low velocity layer exist evidence under the station which the wave of recorded clear.The area where the low velocity layer existed more evidence,the more earthquakes would occur. The result analyzed shows that there may be a low velocity layer existed under the south channel of TaiWan and the oversea of Dongshang,Qunzhou, Zhangahou and YongAn of Fujian province. Some history huge earthquakes in Fujian province occurred just in these areas.
This paper analyze mostly the character of P-wave in one earthquake in the overseas of Henchun Taiwan(O∶2003-2-8,15∶21,MS 5.2,n-lat∶21.1o,e-lon:121.44o).First,we analyze the head wave PN, it shows that it's good in linearity relation,and the value of PN velocity counted out is same to the crust model using in the list of pass time of HuaNan seism.Then we analyze the succedent wave,found that the wave recorded exist evidence different phenomenon whether the earthquake radial traverse the island of Taiwan, that it will be recorded a other phase after the head wave when the radial does not traverse the island of Taiwan,and it will do not exist or not evidence when the radial traverses the island of Taiwan.The evidence character in this succedent wave phase is that the gap of arrive-time to the head wave would minish by the increase of distance of epicenter.According this,the author thinks it may be the wave of,it is the reflect wave of double-range in the earth's crust.And it will show the existing of the low velocity layer.The low velocity layer exist evidence under the station which the wave of recorded clear.The area where the low velocity layer existed more evidence,the more earthquakes would occur. The result analyzed shows that there may be a low velocity layer existed under the south channel of TaiWan and the oversea of Dongshang,Qunzhou, Zhangahou and YongAn of Fujian province. Some history huge earthquakes in Fujian province occurred just in these areas.
引文
[1]刘序俨、林继华、王志鹏、郭逢英,福建沿海地球动力学特征浅析,地壳形变与地震,19(增刊1),1999。
[2]孟晓春等,地震观测与分析技术,地震出版社。
[3]陈步云、高文海,贾家湾-沙园剖面地壳上地幔的深部结构,中国大陆深部构造的研究与进展。
[4]廖其林、王振明等,泉州-汕头地区地壳及上地幔速度结构的初步研究,中国大陆深部构造的研究与进展。
[5]王洪涛、陈箴,城市化防震减灾经济研究,福建地震,14(4),1998。
[2]孟晓春等,地震观测与分析技术,地震出版社。
[3]陈步云、高文海,贾家湾-沙园剖面地壳上地幔的深部结构,中国大陆深部构造的研究与进展。
[4]廖其林、王振明等,泉州-汕头地区地壳及上地幔速度结构的初步研究,中国大陆深部构造的研究与进展。
[5]王洪涛、陈箴,城市化防震减灾经济研究,福建地震,14(4),1998。
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