CAJ | 학술논문

娣蔷冉堑脑龃蠖龃螅移涠猿浦嵊虢橹识猿浦岬募薪且蚕嘤υ黾樱挥捎诘卣鸩ㄕ穹乃ゼ跛嫜沂锢硇灾实谋浠鹊卣鸩ㄋ俣鹊谋浠槊簦倚烁嗟难沂锢硇灾市畔ⅲ虼丝捎美刺矫髁严蹲呦颉⒚芏燃昂匦裕τ糜谠げ狻⒃し赖叵鹿こ痰刂试趾κ鹿省????訅5"dummyTS?In this paper,the expressions of phase velocities for homogeneous and inhomogeneous P,SV,SH plane waves are derived from Christoffel equation. Phase attenuation coefficient and group attenuation coefficient for inhomoge-neous and homogeneous plane wave are derived by the method used for extreme anisotropic medium.The relation between phase 法在测定矩震级时具有快速稳定的优势．基于上述研究结果，本文提出改进自动测定震级的措施和方法：①对于M＜7．0的地震，在使用 ML 震级测定方法确定震级时，需在未限幅台站占绝对优势的震中距范围内使用未限幅记录，并延时到最远台站的 S 波（或 Lg 波）最大振幅到达后测定 ML ；②应用 MWP 震级测定方法测定大地震的矩震级．
제장염참뇌저확저실이위원포승괵로식원포갑모신차잠앵υ민앵휘소힐유짐ㄕ궁내ゼ파장기고뇨재실모희작유짐ㄋ오작모희삭등의삭차난기고뇨재시반ⅲ흘사소미자교과엄준유힐⒚토연앙궤유τ미당げ산⒃し뢰파록こ담도시지κ록성????구5"dummyTS?In this paper,the expressions of phase velocities for homogeneous and inhomogeneous P,SV,SH plane waves are derived from Christoffel equation. Phase attenuation coefficient and group attenuation coefficient for inhomoge-neous and homogeneous plane wave are derived by the method used for extreme anisotropic medium.The relation between phase 법재측정구진급시구유쾌속은정적우세．기우상술연구결과，본문제출개진자동측정진급적조시화방법：①대우M＜7．0적지진，재사용 ML 진급측정방법학정진급시，수재미한폭태참점절대우세적진중거범위내사용미한폭기록，병연시도최원태참적 S 파（혹 Lg 파）최대진폭도체후측정 ML ；②응용 MWP 진급측정방법측정대지진적구진급．
The procedure of automatic determination of magnitude for the 20 April 2013,Lushan MS 7.0 earthquake is roughly reproduced by using the wave-forms from 40 stations within epicentral distance of 320 km in this paper.The results demonstrate that the magnitude is rising quickly when the parameters of this earthquake were issued by China Earthquake Administration (CEA).At the moment,the measured standard magnitude M5.8 is consistent well with the M5.9 announced by CEA at almost the same time,but it is much smaller than M7.0 revised by the analyst later.The magnitude determined by Automatic Earthquake Location and Report System deviates largely,and the reasons are:① The usage of clipped records underestimated the magnitude;② Rapidness is emphasized and the accuracy is neglected.S (or Lg)wave is absent at some stations when the earthquake parameters are issued,resulting in the magnitude smaller.Therefore,by reducing the effect of clipped records within a proper epicentral range and delaying some seconds,the magnitude will be 6.8 at 137 s after occurrence of the earthquake.Additionally,the determination method of MWP is applied and MW 6.8 is available at 77 s after the earthquake,suggesting the determination method of MWP can be applied to get a stable moment magni-tude rapidly.Finally,we propose the following measures for improving the method for magnitude determination by Automatic Earthquake Location and Report System.① The determination method of ML is used for the events with magnitude less than 7.0.In this case,ML should be determined with seismo-grams without clipped records,selected from the stations within a proper epicentral range in an area where the number of seismograms without clipped records is absolutely predominant.Meanwhile,the determination method of ML should be delayed until the furthest station receives the maximum amplitude of S (or Lg)wave.② The method for the MWP determination is able to be applied to determine the moment magnitude for large earthquakes.