A Short History of Nearly Everything-第44章

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his；　measuring　earthquakes　is　not　always　an　exact　science；　particularly　wheninterpreting　readings　from　remote　locations。　at　all　events；　both　quakes　were　whopping。　the1960　quake　not　only　caused　widespread　damage　across　coastal　south　america；　but　also　set　offa　giant　tsunami　that　rolled　six　thousand　miles　across　the　pacific　and　slapped　away　much　ofdowntown　hilo；　hawaii；　destroying　five　hundred　buildings　and　killing　sixty　people。　similarwave　surges　claimed　yet　more　victims　as　far　away　as　japan　and　the　philippines。

for　pure；　focused；　devastation；　however；　probably　the　most　intense　earthquake　in　recordedhistory　was　one　that　struck—and　essentially　shook　to　pieces—lisbon；　portugal；　on　all　saintsday　（november　1）；　1755。　just　before　ten　in　the　morning；　the　city　was　hit　by　a　suddensideways　lurch　now　estimated　at　magnitude　9。0　and　shaken　ferociously　for　seven　full　minutes。

the　convulsive　force　was　so　great　that　the　water　rushed　out　of　the　city’s　harbor　and　returnedin　a　wave　fifty　feet　high；　adding　to　the　destruction。　when　at　last　the　motion　ceased；　survivorsenjoyed　just　three　minutes　of　calm　before　a　second　shock　came；　only　slightly　less　severe　thanthe　first。　a　third　and　final　shock　followed　two　hours　later。　at　the　end　of　it　all；　sixty　thousandpeople　were　dead　and　virtually　every　building　for　miles　reduced　to　rubble。　the　san　franciscoearthquake　of　1906；　for　parison；　measured　an　estimated　7。8　on　the　richter　scale　andlasted　less　than　thirty　seconds。

earthquakes　are　fairly　mon。　every　day　on　average　somewhere　in　the　world　there　aretwo　of　magnitude　2。0　or　greater—that’s　enough　to　give　anyone　nearby　a　pretty　good　jolt。

although　they　tend　to　cluster　in　certain　places—notably　around　the　rim　of　the　pacific—theycan　occur　almost　anywhere。　in　the　united　states；　only　florida；　eastern　texas；　and　the　uppermidwest　seem—so　far—to　be　almost　entirely　immune。　new　england　has　had　two　quakes　ofmagnitude　6。0　or　greater　in　the　last　two　hundred　years。　in　april　2002；　the　region　experienceda　5。1　magnitude　shaking　in　a　quake　near　lake　champlain　on　the　new　york–vermont　border；causing　extensive　local　damage　and　（i　can　attest）　knocking　pictures　from　walls　and　childrenfrom　beds　as　far　away　as　new　hampshire。

the　most　mon　types　of　earthquakes　are　those　where　two　plates　meet；　as　in　californiaalong　the　san　andreas　fault。　as　the　plates　push　against　each　other；　pressures　build　up　untilone　or　the　other　gives　way。　in　general；　the　longer　the　interval　between　quakes；　the　greater　thepent…up　pressure　and　thus　the　greater　the　scope　for　a　really　big　jolt。　this　is　a　particular　worryfor　tokyo；　which　bill　mcguire；　a　hazards　specialist　at　university　college　london；　describesas　“the　city　waiting　to　die”　（not　a　motto　you　will　find　on　many　tourism　leaflets）。　tokyo　standson　the　boundary　of　three　tectonic　plates　in　a　country　already　well　known　for　its　seismicinstability。　in　1995；　as　you　will　remember；　the　city　of　kobe；　three　hundred　miles　to　the　west；was　struck　by　a　magnitude　7。2　quake；　which　killed　6；394　people。　the　damage　was　estimatedat　99　billion。　but　that　was　as　nothing—well；　as　paratively　little—pared　with　whatmay　await　tokyo。

tokyo　has　already　suffered　one　of　the　most　devastating　earthquakes　in　modern　times。　onseptember　1；　1923；　just　before　noon；　the　city　was　hit　by　what　is　known　as　the　great　kantoquake—an　event　more　than　ten　times　more　powerful　than　kobe’s　earthquake。　two　hundredthousand　people　were　killed。　since　that　time；　tokyo　has　been　eerily　quiet；　so　the　strainbeneath　the　surface　has　been　building　for　eighty　years。　eventually　it　is　bound　to　snap。　in　1923；tokyo　had　a　population　of　about　three　million。　today　it　is　approaching　thirty　million。　nobodycares　to　guess　how　many　people　might　die；　but　the　potential　economic　cost　has　been　put　ashigh　as　7　trillion。

even　more　unnerving；　because　they　are　less　well　understood　and　capable　of　occurringanywhere　at　any　time；　are　the　rarer　type　of　shakings　known　as　intraplate　quakes。　thesehappen　away　from　plate　boundaries；　which　makes　them　wholly　unpredictable。　and　becausethey　e　from　a　much　greater　depth；　they　tend　to　propagate　over　much　wider　areas。　themost　notorious　such　quakes　ever　to　hit　the　united　states　were　a　series　of　three　in　newmadrid；　missouri；　in　the　winter　of　1811–12。　the　adventure　started　just　after　midnight　ondecember　16　when　people　were　awakened　first　by　the　noise　of　panicking　farm　animals　（therestiveness　of　animals　before　quakes　is　not　an　old　wives’　tale；　but　is　in　fact　well　established；though　not　at　all　understood）　and　then　by　an　almighty　rupturing　noise　from　deep　within　theearth。　emerging　from　their　houses；　locals　found　the　land　rolling　in　waves　up　to　three　feet　highand　opening　up　in　fissures　several　feet　deep。　a　strong　smell　of　sulfur　filled　the　air。　theshaking　lasted　for　four　minutes　with　the　usual　devastating　effects　to　property。　among　thewitnesses　was　the　artist　john　james　audubon；　who　happened　to　be　in　the　area。　the　quakeradiated　outward　with　such　force　that　it　knocked　down　chimneys　in　cincinnati　four　hundredmiles　away　and；　according　to　at　least　one　account；　“wrecked　boats　in　east　coast　harbors　and　。

。　。　even　collapsed　scaffolding　erected　around　the　capitol　building　in　washington；　d。c。”　onjanuary　23　and　february　4　further　quakes　of　similar　magnitude　followed。　new　madrid　hasbeen　silent　ever　since—but　not　surprisingly；　since　such　episodes　have　never　been　known　tohappen　in　the　same　place　twice。　as　far　as　we　know；　they　are　as　random　as　lightning。　the　nextone　could　be　under　chicago　or　paris　or　kinshasa。　no　one　can　even　begin　to　guess。　and　whatcauses　these　massive　intraplate　rupturings？　something　deep　within　the　earth。　more　than　thatwe　don’t　know。

by　the　1960s　scientists　had　grown　sufficiently　frustrated　by　how　little　they　understood　ofthe　earth’s　interior　that　they　decided　to　try　to　do　something　about　it。　specifically；　they　got　theidea　to　drill　through　the　ocean　floor　（the　continental　crust　was　too　thick）　to　the　mohodiscontinuity　and　to　extract　a　piece　of　the　earth’s　mantle　for　examination　at　leisure。　thethinking　was　that　if　they　could　understand　the　nature　of　the　rocks　inside　the　earth；　they　mightbegin　to　understand　how　they　interacted；　and　thus　possibly　be　able　to　predict　earthquakes　andother　unwele　events。

the　project　became　known；　all　but　inevitably；　as　the　mohole　and　it　was　pretty　welldisastrous。　the　hope　was　to　lower　a　drill　through　14；000　feet　of　pacific　ocean　water　off　thecoast　of　mexico　and　drill　some　17；000　feet　through　relatively　thin　crustal　rock。　drilling　froma　ship　in　open　waters　is；　in　the　words　of　one　oceanographer；　“like　trying　to　drill　a　hole　in　thesidewalks　of　new　york　from　atop　the　empire　state　building　using　a　strand　of　spaghetti。”

every　attempt　ended　in　failure。　the　deepest　they　penetrated　was　only　about　600　feet。　themohole　became　known　as　the　no　hole。　in　1966；　exasperated　with　ever…rising　costs　and　noresults；　congress　killed　the　project。

four　years　later；　soviet　scientists　decided　to　try　their　luck　on　dry　land。　they　chose　a　spot　onrussia’s　kola　peninsula；　near　the　finnish　border；　and　set　to　work　with　the　hope　of　drilling　toa　depth　of　fifteen　kilometers。　the　work　proved　harder　than　expected；　but　the　soviets　weremendably　persistent。　when　at　last　they　gave　up；　nineteen　years　later；　they　had　drilled　to　adepth　of　12；262　meters；　or　about　7。6　miles。　bearing　in　mind　that　the　crust　of　the　earthrepresents　only　about　0。3　percent　of　the　planet’s　volume　and　that　the　kola　hole　had　not　cuteven　one…third　of　the　way　through　the　crust；　we　can　hardly　claim　to　have　conquered　theinterior。

interestingly；　even　though　the　hole　was　modest；　nearly　everything　about　it　was　surprising。

seismic　wave　studies　had　led　the　scientists　to　predict；　and　pretty　confidently；　that　they　wouldencounter　sedimentary　rock　to　a　depth　of　4；700　meters；　followed　by　granite　for　the　next　2；300meters　and　basalt　from　there　on　down。　in　the　event；　the　sedimentary　layer　was　50　percentdeeper　than　expected　and　the　basaltic　layer　was　never　found　at　all。　moreover；　the　world　downthere　was　far　warmer　than　anyone　had　expected；　with　a　temperature　at　10；000　meters　of　180degrees　centigrade；　nearly　twice　the　forecasted　level。　most　surprising　of　all　was　that　the　rockat　that　depth　was　saturated　with　water—something　that　had　not　been　thought　possible。

because　we　can’t　see　into　the　earth；　we　have　to　use　other　techniques；　which　mostly　involvereading　waves　as　they　travel　through　the　interior。　we　also　know　a　little　bit　about　the　mantlefrom　what　are　known　as　kimberlite　pipes；　where　diamonds　are　formed。　what　happens　is　thatdeep　in　the　earth　there　is　an　explosion　that　fires；　in　effect；　a　cannonball　of　magma　to　thesurface　at　supersonic　speeds。　it　is　a　totally　random　event。　a　kimberlite　pipe　could　explode　inyour　backyard　as　you　read　this。　because　they　e　up　from　such　depths—up　to　120　milesdown—kimberlite　pipes　bring　up　all　kinds　of　things　not　normally　found　on　or　near　thesurface：　a　rock　called　peridotite；　crystals　of　olivine；　and—just　occasionally；　in　about　one　pipein　a　hundred—diamonds。　lots　of　carbon　es　up　with　kimberlite　ejecta；　but　most　isvaporized　or　turns　to　graphite。　only　occasionally　does　a　hunk　of　it　shoot　up　at　just　the　rightspeed　and　cool　down　with　the　necessary　swiftness　to　bee　a　diamond。　it　was　such　a　pipet