万物简史英文版_比尔·布莱森-第60章

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evacuating　yellowstone　would　never　be　easy。　the　park　gets　some　three　million　visitors　ayear；　mostly　in　the　three　peak　months　of　summer。　the　park鈥檚　roads　are　paratively　few　andthey　are　kept　intentionally　narrow；　partly　to　slow　traffic；　partly　to　preserve　an　air　ofpicturesqueness；　and　partly　because　of　topographical　constraints。　at　the　height　of　summer；　itcan　easily　take　half　a　day　to　cross　the　park　and　hours　to　get　anywhere　within　it。　鈥渨heneverpeople　see　animals；　they　just　stop；　wherever　they　are；鈥潯�doss　says。　鈥渨e　get　bear　jams。　we　getbison　jams。　we　get　wolf　jams。鈥�

in　the　autumn　of　2000；　representatives　from　the　u。s。　geological　survey　and　national　parkservice；　along　with　some　academics；　met　and　formed　something　called　the　yellowstonevolcanic　observatory。　four　such　bodies　were　in　existence　already鈥攊n　hawaii；　california；alaska；　and　washington鈥攂ut　oddly　none　in　the　largest　volcanic　zone　in　the　world。　the　yvois　not　actually　a　thing；　but　more　an　idea鈥攁n　agreement　to　coordinate　efforts　at　studying　andanalyzing　the　park鈥檚　diverse　geology。　one　of　their　first　tasks；　doss　told　me；　was　to　draw　up　an鈥渆arthquake　and　volcano　hazards　plan鈥濃�攁　plan　of　action　in　the　event　of　a　crisis。

鈥渢here　isn鈥檛　one　already？鈥潯�i　said。

鈥渘o。　afraid　not。　but　there　will　be　soon。鈥�

鈥渋sn鈥檛　that　just　a　little　tardy？鈥�

he　smiled。　鈥渨ell；　let鈥檚　just　say　that　it鈥檚　not　any　too　soon。鈥�

once　it　is　in　place；　the　idea　is　that　three　people鈥攃hristiansen　in　menlo　park；　california；professor　robert　b。　smith　at　the　university　of　utah；　and　doss　in　the　park鈥攚ould　assess　thedegree　of　danger　of　any　potential　cataclysm　and　advise　the　park　superintendent。　thesuperintendent　would　take　the　decision　whether　to　evacuate　the　park。　as　for　surroundingareas；　there　are　no　plans。　if　yellowstone　were　going　to　blow　in　a　really　big　way；　you　would　beon　your　own　once　you　left　the　park　gates。

of　course　it　may　be　tens　of　thousands　of　years　before　that　day　es。　doss　thinks　such　aday　may　not　e　at　all。　鈥渏ust　because　there　was　a　pattern　in　the　past　doesn鈥檛　mean　that　it　stillholds　true；鈥潯�he　says。　鈥渢here　is　some　evidence　to　suggest　that　the　pattern　may　be　a　series　ofcatastrophic　explosions；　then　a　long　period　of　quiet。　we　may　be　in　that　now。　the　evidencenow　is　that　most　of　the　magma　chamber　is　cooling　and　crystallizing。　it　is　releasing　itsvolatiles；　you　need　to　trap　volatiles　for　an　explosive　eruption。鈥�

in　the　meantime　there　are　plenty　of　other　dangers　in　and　around　yellowstone；　as　was　madedevastatingly　evident　on　the　night　of　august　17；　1959；　at　a　place　called　hebgen　lake　justoutside　the　park。　at　twenty　minutes　to　midnight　on　that　date；　hebgen　lake　suffered　acatastrophic　quake。　it　was　magnitude　7。5；　not　vast　as　earthquakes　go；　but　so　abrupt　andwrenching　that　it　collapsed　an　entire　mountainside。　it　was　the　height　of　the　summer　season；though　fortunately　not　so　many　people　went　to　yellowstone　in　those　days　as　now。　eightymillion　tons　of　rock；　moving　at　more　than　one　hundred　miles　an　hour；　just　fell　off　themountain；　traveling　with　such　force　and　momentum　that　the　leading　edge　of　the　landslide　ranfour　hundred　feet　up　a　mountain　on　the　other　side　of　the　valley。　along　its　path　lay　part　of　therock　creek　campground。　twenty…eight　campers　were　killed；　nineteen　of　them　buried　toodeep　ever　to　be　found　again。　the　devastation　was　swift　but　heartbreakingly　fickle。　threebrothers；　sleeping　in　one　tent；　were　spared。　their　parents；　sleeping　in　another　tent　besidethem；　were　swept　away　and　never　seen　again。

鈥渁　big　earthquake鈥攁nd　i　mean　big鈥攚ill　happen　sometime；鈥潯�doss　told　me。　鈥測ou　cancount　on　that。　this　is　a　big　fault　zone　for　earthquakes。鈥�

despite　the　hebgen　lake　quake　and　the　other　known　risks；　yellowstone　didn鈥檛　getpermanent　seismometers　until　the　1970s。

if　you　needed　a　way　to　appreciate　the　grandeur　and　inexorable　nature　of　geologic　processes；you　could　do　worse　than　to　consider　the　tetons；　the　sumptuously　jagged　range　that　stands　justto　the　south　of　yellowstone　national　park。　nine　million　years　ago；　the　tetons　didn鈥檛　exist。

the　land　around　jackson　hole　was　just　a　high　grassy　plain。　but　then　a　forty…mile…long　faultopened　within　the　earth；　and　since　then；　about　once　every　nine　hundred　years；　the　tetonsexperience　a　really　big　earthquake；　enough　to　jerk　them　another　six　feet　higher。　it　is　theserepeated　jerks　over　eons　that　have　raised　them　to　their　present　majestic　heights　of　seventhousand　feet。

that　nine　hundred　years　is　an　average鈥攁nd　a　somewhat　misleading　one。　according　torobert　b。　smith　and　lee　j。　siegel　in　windows　into　the　earth　；　a　geological　history　of　theregion；　the　last　major　teton　quake　was　somewhere　between　about　five　and　seven　thousandyears　ago。　the　tetons；　in　short；　are　about　the　most　overdue　earthquake　zone　on　the　planet。

hydrothermal　explosions　are　also　a　significant　risk。　they　can　happen　anytime；　pretty　muchanywhere；　and　without　any　predictability。　鈥測ou　know；　by　design　we　funnel　visitors　intothermal　basins；鈥潯�doss　told　me　after　we　had　watched　old　faithful　blow。　鈥渋t鈥檚　what　they　eto　see。　did　you　know　there　are　more　geysers　and　hot　springs　at　yellowstone　than　in　all　therest　of　the　world　bined？鈥�

鈥渋　didn鈥檛　know　that。鈥�

he　nodded。　鈥渢en　thousand　of　them；　and　nobody　knows　when　a　new　vent　might　open。鈥潯�wedrove　to　a　place　called　duck　lake；　a　body　of　water　a　couple　of　hundred　yards　across。　鈥渋t　lookspletely　innocuous；鈥潯�he　said。　鈥渋t鈥檚　just　a　big　pond。　but　this　big　hole　didn鈥檛　used　to　be　here。

at　some　time　in　the　last　fifteen　thousand　years　this　blew　in　a　really　big　way。　you鈥檇　have　hadseveral　tens　of　millions　of　tons　of　earth　and　rock　and　superheated　water　blowing　out　athypersonic　speeds。　you　can　imagine　what　it　would　be　like　if　this　happened　under；　say；　theparking　lot　at　old　faithful　or　one　of　the　visitors鈥櫋�centers。鈥潯�he　made　an　unhappy　face。

鈥渨ould　there　be　any　warning？鈥�

鈥減robably　not。　the　last　significant　explosion　in　the　park　was　at　a　place　called　pork　chopgeyser　in　1989。　that　left　a　crater　about　five　meters　across鈥攏ot　huge　by　any　means；　but　bigenough　if　you　happened　to　be　standing　there　at　the　time。　fortunately；　nobody　was　around　sonobody　was　hurt；　but　that　happened　without　warning。　in　the　very　ancient　past　there　have　beenexplosions　that　have　made　holes　a　mile　across。　and　nobody　can　tell　you　where　or　when　thatmight　happen　again。　you　just　have　to　hope　that　you鈥檙e　not　standing　there　when　it　does。鈥�

big　rockfalls　are　also　a　danger。　there　was　a　big　one　at　gardiner　canyon　in　1999；　but　againfortunately　no　one　was　hurt。　late　in　the　afternoon；　doss　and　i　stopped　at　a　place　where　therewas　a　rock　overhang　poised　above　a　busy　park　road。　cracks　were　clearly　visible。　鈥渋t　could　goat　any　time；鈥潯�doss　said　thoughtfully。

鈥測ou鈥檙e　kidding；鈥潯�i　said。　there　wasn鈥檛　a　moment　when　there　weren鈥檛　two　cars　passingbeneath　it；　all　filled　with；　in　the　most　literal　sense；　happy　campers。

鈥渙h；　it鈥檚　not　likely；鈥潯�he　added。　鈥渋鈥檓　just　saying　it　could。　equally　it　could　stay　like　that　fordecades。　there鈥檚　just　no　telling。　people　have　to　accept　that　there　is　risk　in　ing　here。　that鈥檚all　there　is　to　it。鈥�

as　we　walked　back　to　his　vehicle　to　head　back　to　mammoth　hot　springs；　doss　added：　鈥渂utthe　thing　is；　most　of　the　time　bad　things　don鈥檛　happen。　rocks　don鈥檛　fall。　earthquakes　don鈥檛occur。　new　vents　don鈥檛　suddenly　open　up。　for　all　the　instability；　it鈥檚　mostly　remarkably　andamazingly　tranquil。鈥�

鈥渓ike　earth　itself；鈥潯�i　remarked。

鈥減recisely；鈥潯�he　agreed。

the　risks　at　yellowstone　apply　to　park　employees　as　much　as　to　visitors。　doss　got　ahorrific　sense　of　that　in　his　first　week　on　the　job　five　years　earlier。　late　one　night；　three　youngsummer　employees　engaged　in　an　illicit　activity　known　as　鈥渉ot…potting鈥濃�攕wimming　orbasking　in　warm　pools。　though　the　park；　for　obvious　reasons；　doesn鈥檛　publicize　it；　not　all　thepools　in　yellowstone　are　dangerously　hot。　some　are　extremely　agreeable　to　lie　in；　and　it　wasthe　habit　of　some　of　the　summer　employees　to　have　a　dip　late　at　night　even　though　it　wasagainst　the　rules　to　do　so。　foolishly　the　threesome　had　failed　to　take　a　flashlight；　which　wasextremely　dangerous　because　much　of　the　soil　around　the　war