Lectures 5 & 6 Earthquakes 2011

Lectures 5 & 6 Earthquakes 2011 - EARTH SC/ENVIR SC...

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Unformatted text preview: EARTH SC/ENVIR SC 1G03 Earth & the Environment Announcements! Labs start: this week! First lab: meet in your assigned Lab room Fieldtrip: Friday, Sept. 30: 1 5 pm Saturday, Oct 1: 9 am -1 pm (Friday preferred as Saturday is almost full) Midterm: Friday Oct 14: in class !"#$%&'(")&*"+,&-)& & !"#$%&'(")&*"+,&-)& & !"#$%&'(")&*"+,&-)& *#$#./&/0#&%1/#&234& 5"$$&1//#,%& Things you Have to Do! Complete the Student Responsibility Contract on Avenue By Fri. Sept 23rd at 4:30pm Should take less than 10min! Grades will not be released on Avenue if not complete Complete the Academic Integrity Quiz on Avenue By Fri. Sept 23rd at 4:30pm Should take less than 10min! Receive a grade of zero on Lab 1 if not complete These quizzes are not graded you just need to complete them & Things you Have to Do! MacRocks Bonus Quiz! Take a walk through campus and learn about the campus geology Bonus quiz that could add up to 1% on your final grade Posted on Avenue Open until Fri. Oct 14th at 4:30pm !"#$%&'()$"*+)(,%'-.*/%,0+'1*23)4** #6/#,%#%&/3&'4#7%12&1/&89:;<&&& Things you had to do! Read Chapter 2 and 4 in Plummer et al. Think about this question9& Why do we need to know about the plate tectonic history of North America?& & !"+4(#&=<=& !"+4(#&=<>& Envir Sc/Earth Sc 1G03 On Shaky Ground EARTHQUAKES * Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC ?1)1,&517&7/(4.@&A2&1&B1+,"/4%#&C<;&#1(/0D41@#&3EE&"/7&,3(/0#17/#(,& .317/&!("%12<&&'0"7&"7&3,#&3E&/0#&$1(+#7/&#1(/0D41@#7&/01/&?1)1,&017& #F#(&#6)#("#,.#%<& & L,&%35,/35,&'3@23H&$1(+#&A4"$%",+7&7033@&F"3$#,/$2&1,%&/0#(#&"7&7#F#(#& <&&& E$33%",+&%4#&/3&1&/74,1B"&+#,#(1/#%&A2&/0#&#1(/0D41@#<& G1(/&3E&0347#7& 751$$35#%&A2& /74,1B"&A4(,&",& *#,%1"H&I"21+"& G(#E#./4(#&J7/1/#K& 1E/#(&?1)1,&517& 7/(4.@&A2&1&7/(3,+& #1(/0D41@#&3EE&"/7& ,3(/0#17/#(,&.317/& !("%12H&I1(.0&>>H& =;>><& & &%&'$()*+$,-.&/$ !"#"$ * Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC '74,1B"&51F#7&75#)/&1512& 0347#7&1,%&.1(7&",&,3(/0#(,& ?1)1,&1,%&)470#%&70")7& 1+(34,%<&& & '0#&/74,1B"&51F#7&/(1F#$#%&E1(& ",$1,%H&/0#&51F#&3E&%#A("7& (1.",+&1.(377&/0#&E1(B$1,%H& .1((2",+&A31/7&1,%&0347#7&5"/0& "/<&& '0#&/74,1B"H&7##,&.(170",+&",/3&& 03B#7&",&N1/3("H&I"21+"&)(#E#./4(#<&01$ M347#7&5#(#&5170#%& 1512&A2&/74,1B"&",& *#,%1"H&I"21+"&G(#E#./4(#& ",&#17/#(,&?1)1,H&1E/#(& ?1)1,&517&7/(4.@&A2&1& B1+,"/4%#&C<;& #1(/0D41@#&3EE&/0#& ,3(/0#17/#(,&.317/<&& & %&'$()*+$,-.&/$ * Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at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agnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC '0#&B1)&3,&/0#&("+0/&70357&0"7/3(".& #1(/0D41@#&1./"F"/2&,#1(&/0#&#)".#,/#(& J7/1(K&E(3B&>CC;&/3&)(#7#,/<&& & S7&7035,&3,&/0#&.(377&7#./"3,H& #1(/0D41@#7&1(#&701$$35&J3(1,+#&%3/7K&1/& /0#&?1)1,&'(#,.0&1,%&",.(#17#&/3&:;;&@B& %#)/0&JA$4#&%3/7K&/351(%7&/0#&5#7/&17& /0#&G1."E".&G$1/#&%"F#7&%##)#(&A#,#1/0& ?1)1,<& "&-/.-5-78$=*)//$"&57-)>$35*)//$7:&$/6?@657-)>$A)>&$ /:)'->4$7:&$*&;37-)>/:-B$?&7'&&>$5);)*$3>@$ &3*7:C63+&$@&B7:D$ 2.34&/$5)6*7&/8$)9$7:&$!"$#&);)4-53;$"6*<&8$ * Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC *#"7B".&51F#7&(#.3(%#%&1(34,%&/0#&53($%<& 0//)9QQ555<"("7<#%4Q%B7Q7#"7B3,<0/B& O1(/0D41@#7&",&T1,1%1&#0U&& O1(/0D41@#7&3E& /0#&$17/&:;&%127& 0//)9QQ#1(/0D41@#7 .1,1%1<,(.1,<+.<.1 Q",%#6V#,+<)0)& & & O1(/0D41@#&",E3(B1/"3,Q7#"7B".&B3,"/3(& 0//)9QQ555<"("7<#%4Q%B7Q7#"7B3,<0/B& 5'%(673'8,*96'8,9*:'()",'3*'%,'* * TWT&N#57&& G37/#%9&*#)&>PH&=;>>&X9=Y&GI&O'&& Z17/&-)%1/#%9&*#)&>PH&=;>>&[9;;&GI&O'&& & & S&7B1$$&#1(/0D41@#&7033@&/0#&+(34,%&",&/0#&\//151&(#+"3,&*4,%12&1E/#(,33,< & O1(/0D41@#7&T1,1%1&71"%&/0#&8<>&B1+,"/4%#&D41@#&517&.#,/(#%&,#1(&]1/",#14H& ^4#<& '0#&/(#B3(H&50".0&0"/&1/&:9>C&)<B<&$3.1$&/"B#&1,%&517&E#$/&A2&73B#&(#7"%#,/7&",& \//151H&.147#%&,3&%1B1+#&1,%&,3A3%2&517&04(/H&/0#&1+#,.2_7&5#A7"/#&71"%< & Z17/&B3,/0H&1,&#1(/0D41@#&.#,/(#%&",&`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`#(B3,/H&N#5& ?#(7#2&1,%&N#5&a3(@<& ?4,#&=:H&=;>;& IX&D41@#& \4/$",#& >< =< :< 8< X< L,/(3%4./"3,& *#"7B".&b1F#7& Z3.1/",+&1,&O1(/0D41@#& O1(/0D41@#&*/(#,+/0& OEE#./7&3E&1,&O1(/0D41@#& & www.seismo.nrcan.gc.ca 0//)9QQ#1(/0D41@#7.1,1%1<,(.1,<+.<.1Q",%#6c#<)0)& 1. Introduction What is an earthquake? Earthquake ! motion or trembling of the ground caused by the sudden displacement of rock Where do most earthquakes occur? At plate margins - Divergent - Convergent - Transform Fig. 3.22 Along (breaks in rocks) surface or buried & & not always associated with m odern plate boundaries A micro earthquake occurred at 03:36:31 (UTC) on Wednesday, September 21, 2005. The magnitude 2.9 event has been located in ONTARIO, CANADA. (This event has been reviewed by a seismologist.) M a g n i t u d e 2.9 D a t e- T i m e W e d n esd a y, Se p t e m b e r 21, 2005 a t 03 : 36 : 31 ( U T C ) = Coordinated Universal Time Tu esd a y, Se p t e m b e r 20, 2005 a t 11 : 36 : 31 P M = local time at epicenter L oc a t ion 46.540°N, 80.980°W D e p t h 0 km (~0 mile) set by location program R egion O N T A R I O , C A N A D A D ist a n c es 5 km (3 miles) NNE (19°) from Su d b u r y, O n t a r io, C a n a d a 11 km (7 miles) SSE (168°) from Va l l e y E ast , O n t a r io, C a n a d a 118 km (74 miles) WNW (282°) from N o r t h B a y, O n t a r io, C a n a d a 319 km (198 miles) NNW (338°) from R i c h mon d H i l l , O n t a r io, C a n a d a 426 km (265 miles) WNW (289°) from O T T A W A , O n t a r io, C a n a d a www.seismo.nrcan.gc.ca Why do earthquakes occur? Stresses acting on rocks & Stress force/unit area Strain deformation or bending in response to stress San Andreas fault - When strain > strength of rock - sudden break or movement Releases energy as SEISMIC WAVES Fig. 3.2 Elastic rebound theory Where does an earthquake originate? Focus! ! point of initial movement on a fault, where seismic waves originate Epicentre point on earth's surface directly above the focus Fig. 3.4 2. Seismic Waves Waves of energy produced by an earthquake ! ! Fig. 3.4 Body Waves travel through the Earth P waves (Primary) compressional very fast, 4-7 km/sec rock vibration parallel to the direction of wave propagation *first to be detected by any monitoring system Fig. 3.5 S waves (Secondary) shear - Slower, (2-5 km/sec) rock vibration perpendicular to direction of wave ! & P will pass through waves fluid S waves will NOT pass through fluids Fig. 3.5 How have seismic waves helped us learn interior? - S waves do NOT pass through outer core liquid Fig. 4.8 Surface Waves travel on the surface ! Slow waves, cause most damage Love waves - Horizontal movement - Rock vibration PERPENDICULAR to direction of wave propagation ! & Fig. 3.5 Rayleigh waves rolling waves - very destructive - similar to wave motion in the oceans & Fig. 3.5 3. Locating an earthquake Seismic waves are detected with a seismometer records motion global network ofseismograph stations seismograph & Seismogram paper record where P waves, S waves can be differentiated Fig. 3.6 www.seismo.nrcan.gc.ca & Canadian seismic monitoring stations Which type of seismic wave will arrive first at a seismograph station? P waves arrive first, then S waves > distance travelled > time difference time-travel curve & Fig. 3.8 Finding the epicentre Use travel-time curve - determines distance to epicentre Need Three or more stations to locate epicentre Fig. 3.10 How can we determine the focus? Through further analysis of seismograms ! Shallow focus Intermediate focus Deep focus < 70km 70 - 350km 350 - 670km 4. Earthquake Strength stopped SEPT 20 How do we determine the size of an earthquake? Measure how much damage caused - the intensity of the Earthquake - Modified Mercalli scale (I-XII) Table 3.2 Charleston, Carolina, 1886 Fig. 3.11 T0",1& & & O7/"B1/#%&G3)4$1/"3,&O6)37#%&/3&O1(/0D41@#&*01@",+& G3/#,/"1$&*/(4./4(#&e1B1+#& O7/<&G3)4$1/"3,& O7/<&I3%"E"#%& O6)374(#&J@&d& G#(.#"F#%&*01@",+& I#(.1$$"&L,/#,7"/2& 6>;;;K& f#7"7/1,/& `4$,#(1A$#& g& [;:@& O6/(#B#& `<&M#1F2& `<&M#1F2& Lg& [C=@& `"3$#,/& M#1F2& `<&M#1F2& `LLL& 8H:;>@& *#F#(#& I3%#(1/#QM#1F2& M#1F2& `LL& >=H:C[@& `#(2&*/(3,+& I3%#(1/#& I3%#(1/#QM#1F2& `L& >XH8P8@& */(3,+& Z"+0/& I3%#(1/#& `& PCH8P;@& I3%#(1/#& `<&Z"+0/& Z"+0/& L`& >C=H;>=@h& Z"+0/& N3,#& N3,#& LLVLLL& VVh& b#1@& N3,#& N3,#& L& VVh& N3/&!#$/& N3,#& N3,#& Calculate amount of energy released - m easure the amplitude of the seismograph variations -represents the magnitude of the earthquake Richter Scale (logarithmic) for every unit increase - ground displacement increases by 10X - energy released increases by 32X Indonesia, 2004 Fig. 3.12 5. Effects of Earthquakes Why do earthquakes cause damage? Ground Shaking (collapse of buildings) & e.g. Mexico City, 1985 Kobe, 1995 Surface faulting Landslides Liquefaction water gets in between sand particles and cause a sinking effect shaking causes liquification of sediment structures collapse San Francisco, 1906 & Kobe, 1995 Fire Tsunamis & Tsunamis Hit shore as very large, very fast waves Water keeps rising for 5-10 mins Wind-generated wave Tsunami Wavelength 400 m 150 km Speed 90 km/hr 750 km/hr Wave height 3- 5 m 15-30 m ! How do tsunamis form? Displacement of sea floor in Water rushes in and overcorrects Creates long, low waves Hilo, Hawaii, 1946 Indonesia Indonesia Dec 26, 2004 Wave height: 15 30m Speed: 750 km/hr ~300,000 killed I million displaced Dec 26, 2004 6.!!Earthquakes in eastern North America How can we tell if we are at risk of earthquakes in eastern North America? Historical Record: - New Madrid (Missouri) 1811-12, [mag 8-9] - Charleston (S. Carolina) 1886. [Mag 7] - Newfoundland New Madrid, Missouri: Dec. 1811, Jan, Feb, 1812 (3 quakes) Probably M8-9 Changed course of Mississippi, created new lakes Damaged well constructed buildings over an area of 235,000 sq. miles Ground shaking felt over 4 million sq. miles Eastern North American earthquakes affect larger areas than western North American earthquakes why? Charleston, South Carolina: 1886 approximately magnitude 7 city flattened, dams burst 110 people died out of a town of 50,000 felt over an area of 1.5 million sq. miles cracked walls in Chicago over 750 miles away Fig. 3.11 Intraplate earthquakes not at plate margins Intraplate earthquakes occur along old "rifted" margins adjacent to oceans e.g. Charleston - along failed rifts e.g. Mississippi valley, St. Lawrence valley Box 2.4 Seismic gaps - inactive portions of a fault - likely sites of future quakes Earthquake prediction change in rock properties change in water levels increase in radon emission tilt of Earth surface animal behaviour patterns of earthquake occurrence Box 3.4 Earthquakes in Canada eh? Fig. 3.13 A lot of fault lines dissipate the earthquake and energy released which aids in decreasign the area affected dramatically Is Vancouver at risk from an earthquake? Box 3.3 Juan de Fuca plate moving east, collides with north american plate along cascadia subduction zone ! Great earthquakes strike every 500 years; M=7, every 30 yrs Past earthquakes M = 8 to 9.5 Is Toronto at risk from an earthquake? Lies close to old suture zone - CMBBZ - weakness in crust - potential site for earthquakes N.American plate moving westward Box 2.5 - Over 50% chance of M=5 earthquake in next 50 years M=7 could occur Why is this important? VACUUM BUILDING 1 PRESSURE RELIEF DUCT 8 REACTORS PICKERING NUCLEAR GENERATING STATION !!! ...
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This note was uploaded on 11/28/2011 for the course ENV SCI 1G03 taught by Professor Padden during the Fall '11 term at McMaster University.

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