地球物理学基础作业03.doc

地球物理学基础（2013）作业03PAGE\*Arabic\*MERGEFORMAT3/NUMPAGES\*Arabic\*MERGEFORMAT3
地球物理学基础（2013）作业03
布置时间：2013-10-8(周二)交作业时间：2013-10-24（周四）
1、翻译（15分）
将英文教材《FundamentalsofGeophysics》的右边第二段翻译成中文，即以“Reflectionseismologyisdirectedprimarilyatfindingthedepthsto…”开头的那一段。
2、名词解释（15分）
首波反射系数共中心点排列动校正合成地震记录
3.Aseismicsurveyisconductedoverlevelgroundconsistingoftwohorizontallayers.Sketchatravel-timediagramthatshowsthearrivalsofthedirectwave,thereflectedwave,andthedoublyrefractedwave.Howcantheseismicvelocityofeachlayerbedeterminedfromthediagram?(25points)
4.Thefollowingtablegivestwo-waytravel-timesofseismicwavesreflectedfromdifferentreflectinginterfacesinahorizontallylayeredmedium.（30points）

(a)Drawaplotof(travel-time)2against(distance)2.
(b)Determinetheverticaltwo-waytravel-time(“echo-time”)andaveragevelocitytoeachreflectinginterface.
(c)Computethedepthofeachreflectorandthethicknessofeachlayer.
(d)Computethetruevelocity(intervalvelocity)ofeachlayer.
(e)Verifyyourresultsbycomputingthetotalverticaltravel-timeforawavereflectedfromthedeepestinterface.
5.Assumethatthethreehorizontalhomogeneousrocklayersinthepreviousproblemshavedensitiesof1800,2200,and2500kgm-3respectively.Thelowestlayeroverliesbasementwithvelocity5.8kms-1anddensity2700kgm-3.(15points)
(a)ComputethereflectionandtransmissioncoefficientsateachinterfaceforaplaneP-wavetravel-lingverticallydownwards.
(b)Calculatewhatfractionoftheinitialenergyofthewaveistransmittedintothebasement.
(c)Calculatethefractionoftheinitialenergycarriedinthereflectionthatreturnstothesurfacefromthebasement.
6.（附加题）AnincidentP-waveisconvertedintorefractedandreflectedP-andS-wavesataninterface.Calculateallthecriticalanglesinthefollowingthreecases,whereαandβaretheP-waveandS-wavevelocities,respectively:

7.（附加题）Thetablebelowgivesup-dipanddown-diptravel-timesofP-wavearrivalsforrefractionprofilesoveraninclinedinterface.Thegeophonesarelaidoutinastraightlinepassingthroughthealternateshot-pointsAandB,whichare2700mapartontheprofile.
(a)Plotthetravel-timecurvesforeachshot-poi