Midterm 2 Study Guide

Midterm 2 Study Guide - W El E_E|.I.IIEI:5._ Mrhrle...

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Unformatted text preview: W El E_E|.I.IIEI:5._ Mrhrle {funversilm P to SV. 51’ n:- P -Sil dues nut natJdL' Ctaltwrt Timl internal Reflectiun Requires ii ltm'er stelucit}.I tn higher eelnt'i'r}r n1erliu|11 It is the mechanism by Iwhich SH wax-es are Lrapped in en: crust tu t'unn Lm-‘e WWI-:5. Hutiltes Law — Stress =5train F= 4'0: -x is distance the spring has been compressed or stretched -F' is the restatrirlg farce -l-< is file IJullt nmdulus -u is shear modulus -‘|’ is young’s mudulus E u .331 . 5 -F‘ waves travel dimugh liquid, mild, and gas -Ea rtli’s mean dens it]! is about 5.5 times. that of 1Mater -Distance of seismugraph stations ranges frtilll [II tu liiii degrees from EQ suurce 4'1 waives rln nut 3n tlmmgl‘l liquid -incident p 1Maire produces and reflected and refracted p and s have -Same happens m vertical S wave [EV wave). ._P AND 5"! TURN INTI?) EACH EITHER -Dties not happen for 5H waves a a. VP— K411“ LEE—F p i p —5‘i-‘ and SH waves can travel faster or slower than each timer -S"u" and SH are perpendicular to the ray path —i"‘ waves are parallel -S waves from [tlcSclSltl are best uhsen-ed la]..- hurizuntal scale. -5H not recorded on 1:ertical. 5"»! not recorded on horiauntal Surface Waves —l.nn.'e wiwes mtwe grrmnr] Frnn1 .sicle in side in ii hnrixmmll plane but at right singlets tn the direction of propagation. —;"'I.rri~.-1: Linciure Rayleigh waves —5H waves trapped in low velocity surface layer by total internal refraction -Must be recorded [in hurizuntal seismugraph —Ra}'leigl1 waves are lilte rnlling tat'ean waves. The circle nun-es in ii t'tauntert'lnt'kwifie motion. Materials disturbed move both vertically and horizontally in a vertical plane. -I'L'1|‘IngHdL' elliptical Imninlt -these waves are spread out into trains of cycles. called dispersion. SIJ'RFA CF. WAVES [iIUF l'u'lflFtF. AFITUHATF SIZE MFAS THAN HHUIV WAVFS -Fu-Cus of the EQ is at F. -.‘i}rrnhnl r: is wave reflects-cl nr miter core's surface. -P'CF would be F wave Il'lrougli LliL' mantle reflected at dte core. -SeF is S waw reflected as a P -T designates reflection at inner cure -SF is 5 wave through mantle Reflected at outer surface as P' -J is through the inner core -P]UKF [irne'es inner L'an- is sulid -5 wave in ll'lliE'F core is SH {I EIIIE Emmi-awn Etl'flsil'irilemJ Ine. Interior Ear-1J1 Scrueture -crust is outermost iajrer of rocks. -Sii ic composition —r.Trntinenrs are EE-TI'II inn thic'lu: -ocean it is uniform iIJlt n1 thickness {umpmed ur basalt 45qu crust is in floating equilibrium on the denser mantle below. flceanic cmst floats lower than cooLinental crust heca use it is thinner and rlenser. This is Why means are above ne'er-mic c'ant. -Cnno‘nenta| crust won’t sub-duet, and [meanic goes under illltl’nfitlfii il'l'lI km of surface {including trust] is lithmphere -uncler it at :1 thickness of 4m Inn is the atlteltospltere —Herween crust .illil'l mantlel is I'I1I'Il'lt] -rnant|e extends from base of crust to depth of 2335 ltrrl —Ruelts are Clnse'st Lt] meltingI point between it'll] and 2m: km —en‘ns.ists of dense silicate rnrlcs. -P and 5 waves go tltltiuglt it —aner mantle is or. 'I-‘t'il'il km -Sei5n1ic low velocityr woe is in the arflteoosphem {lUfl-lmkmi -Po11.rroo1'ohic phase boundaries at 4GB and 650 km in mantle -t‘.luter core ls a shell composed of liquid -composerl of iron. oxygen. silicon. -S waves don't go d'uoogh it. {how we know its liquid) —Rel'let.'l'|t:|tls of El and P waves take place we" I]1ere vlnoer core is a solid boundary —Iir_'i[|!1‘.'1' than outer eon.- _ ’s w small U1 It; sin 32 1'12 Til +1 waves angle frnm CENTER LTN'F. is always smaller -lncident SH has NO mnde ctmyersittn Waltzes Fat-thrntalte retarding instruments are called seismngraphs EQ recnrds are called selsmugrants {TI-IE WAVI'NG LINES} device that tramfunns gruumi cnuLiun into electrical signal is Seismmneter -Ft'ttm a seismugt'am ynu can find us: hyfflk‘elllel' lncatitm, magnithle, and suurce Tirttperties ttf an Fl}. -mict'trseistns are lncal disturbances in the earth {tt'aft'ic. wind, etc) —lu‘."i].llt]l.1 til E0 is fuutltl by n'teasur'ttlg distance [rum laws 1“ setstntlgranh. Clggter B: — Size at an EQ -isuseisma| lines are lines ut' nuints where there is equal damage nr intensity. —han:ler rnclt currelates tn less damage In structures. —Trttensities ttf Fle rlii'Fer FrtJrn plat-e trt- 'I1lilt'l-‘l in an area het'mtse ttf nn-t'lt strttt'ttlre anrl snil pmpetties. -st:lt lmils slip ianrl lnse their t'nhesiye strength. —lntensity is net larger at the epieenter -In the Richter scale. when magnitude gees up by une unit, the amplitude increases in titnes Magnitude is used in Fl- ways' -Flet11gni'ced by nettnle as a measure nf relative size. and penple DIJITI'ElEIIE n'tagnltude Willi the severity tfl' an EQ —Use-rl tn rnttnitttr t'nrnprehensiye |1l1t'll-'-ilr tests, and tn rllfil‘lliEillfil'l hetweuen undergt'nuntl explnsinn and an El uf natural ca uses. —Magnilud.es Elf previtrus Et'ls art.- uSed In appttrsitnale I'IututL' EQ and design stmt‘tures that can withstand Fl 2:. -EQ is t'attltet' away ft'nm statintt clues NOT mean smaller mag. w 1 1 I - -Measute distance tn the fucus using S-P —Meias1tre height ttf rrtait wave mntinn -Fincl appmpt'iate pnint -Deep Ens have small trains at surface waves. -Measut'ing unifnt'm magnitude mat clues nnt depend u-n presence at absence nf surface waves is the seismic rntJrnt-Irtt. -Descriliing nyetall siae ut' the snu rce is by measuring the seismic energy radiated thruugh the waves at the melts. —5eismit mument yields a tnnstant scale at earthquake size -Has greater reliability at attsnlute size and is limit: mhust —5trnng mutiun seismttgraj'l hs are called accelugraplts sfititne peaks ui' high frequency was-es reach acceleratimts equal lt] gravity -Generally. the vertical at‘teleratinn is less than the peak hnriznntal acceleratinn. -".-'et'tica| mntintt is P wayes. Itnrianntal is 5 KI'IIZIW that mantle is nlitrine because: Ju'n. “Us. and D match seisnnc eelttcittes —ttent:tlitl1s frnm ynlt'nnnes -has 't"[llL"fll.'I[H.‘5 — cllamnnds -t:|1hislite stlits = plat-e where mnlm is e'tpnse-rl -t'a rbtmat‘etnas meteurites are nlivine -uceattic crust is at Iu-Ipcer eleyatinn than ctmtinental crust cIUe tn isnstacy ...
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Midterm 2 Study Guide - W El E_E|.I.IIEI:5._ Mrhrle...

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