Ngobusuku bangoJulayi 9, 1958, iLituya Bay yase-Alaska yabhekana nesinye sezenzakalo ezimangalisayo enkumbulo ephilayo. Ukuzamazama komhlaba okulinganiselwa ku-7,9 esikalini sikaRichter kwazamazamisa yonke indawo ethekwini. Inkinga kwakungeyona nje ukuzamazama komhlaba ngokwako, kodwa amagagasi owakhiqiza, ubude obungaphezu kwengxenye yekhilomitha. Igagasi elikhulu kunawo wonke emlandweni orekhodiwe. Ngabunjwa ngu i-tsunami enkulu kunazo zonke emhlabeni eyaziwa kuze kube namuhla.
Kulesi sihloko sizokutshela konke okudingeka ukwazi mayelana ne-tsunami enkulu kunazo zonke emhlabeni, izici zayo kanye nomonakalo eyawubangela.
I-tsunami enkulu kunazo zonke emhlabeni
I-Fairweather Fault itholakala eduze kwaseLituya Bay e-Alaska. Ngakho-ke, kuyindawo yomsebenzi wokuzamazama komhlaba, lapho ukuzamazama komhlaba okukodwa noma okunye okukhulu kwenzeka njalo emashumini ambalwa eminyaka. Kodwa-ke, kusukela ngo-1958 kuphezulu kakhulu. Ngaphezu kwalokho, kwanezelwa esinye isici esibalulekile: idwala eliwela emanzini futhi ladala amagagasi angakaze abonwe ngaphambili.
Kulinganiselwa ukuthi ama-cubic metres ayizigidi ezingu-30 zamatshe awe ukusuka ekuphakameni okungamamitha angu-900. Leli dwala elihlanyayo alikwenzi lutho kodwa libangela amagagasi amakhulu. Yize engekho amafayela ayingcaca walesi sikhathi noma amathuluzi angawaqopha, kunobufakazi bakamuva. Emashumini eminyaka kamuva, lapho izinsalela zomonakalo wamagagasi zisabonakala, sithola ubufakazi. Ukuhlaziywa kuka-2010 kwegquma eliseduze kwembula izinguquko ezitshalweni eyake yaba nazo. Cishe ngamamitha angu-500 ukuphakama, kunoshintsho olubalulekile lwezitshalo ezincane kunaphezulu. Izazi zokuma komhlaba nabacwaningi balinganisela ukuthi amagagasi angafinyelela ubude obungamamitha angu-524.
Umzamo wokunciphisa ukulimala
Ukuvalwa okuhlobene kweLituya Bay akuzange kusize ekunciphiseni izinhlekelele. Njengesikhala samanzi esizungezwe izwe, igagasi likhukhula yonke into eseduze futhi, ngendlela efanayo, lenza ibe yinde ngokuncipha indawo esemaceleni. Lalilikhulu kakhulu yashanela izwe elizungezile futhi ekugcineni yachithekela eGulf of Alaska.
Indawo enkulu kunazo zonke ngaleso sikhathi kwakuyi-Yakutat, eyalimala kancane uma kucatshangelwa ubukhulu bokuzamazama komhlaba nobukhulu bamagagasi. Kuyaziwa ukuthi ingqikithi yabantu abathathu bafa esiqhingini saseYakutat, esiqhele ngamakhilomitha angu-200 ukusuka echwebeni, ngoba abanye babo bangcwatshwa olwandle. Emuva ethekwini, abantu ababili ababesesikebheni sokudoba nabo bakhukhulwa.
Le ndawo iyingxenye yeGlacier Bay National Park and Preserve, ngakho indawo ezungezile ayinamuntu, kodwa izikebhe ezintathu zokudoba zazingaphakathi ethekwini lapho kuzamazama umhlaba. Umkhumbi kaVivian noBill Swanson u-Badger wathwalwa wayiswa emlonyeni wetheku ngamagagasi "eshelela enqamula eningizimu ye-Alaska" futhi ekugcineni wacwila. Ngenhlanhla umshado wahlengwa ngesinye isikebhe. U-Howard Uhlrich kanye nendodana yakhe eneminyaka engu-7 ubudala bakwazile ukugwema amagagasi ngesikebhe sabo i-Edrie, belibangise ngakubo. Kodwa u-Orville Wagner nomkakhe bagxojwa udonga lwamanzi eSomermore bafa.
E-Yakutat, okuwukuphela kwendawo yokuhlala unomphela eduze nesizinda ngaleso sikhathi, ingqalasizinda enjengamabhuloho, amadokhu namapayipi ayonakele. Kwabhidlika umbhoshongo nendlu yangasese yalimala kangangokuthi yayingenakulungiseka. Amathumba esihlabathi nemifantu kwavela ogwini oluseningizimu-mpumalanga, futhi izintambo ezisekela isimiso sokuxhumana sase-Alaska zanqanyulwa.
Amagagasi e-tsunami enkulu kunazo zonke emhlabeni adale umonakalo ezitshalweni ze-promontory ezungeze indawo lapho idwala liwele khona, lifinyelela kumamitha angu-520 ukuphakama, kanye nasogwini lwechweba.
i-geology ye-seismic
Okwenzeka eLituya kuyisici salokho okubizwa ngokuthi ama-tsunami amakhulu. Amagagasi angaphezu kwamamitha angu-100 kuphela angena kulesi sigaba. Indawo yase-Alaska lapho kwenzeke khona ukuzamazama komhlaba isendaweni enephutha ukunyakaza kwayo okubangele ukuzamazama komhlaba okukhulu. Indawo yaseLituya Bay inomlando wezenzakalo ze-tsunami, kodwa i-eUmcimbi wango-1958 wawungowokuqala ukuqoshwa ngedatha eyanele.
Nakuba kusaphikiswana ukuthi yiziphi inhlanganisela yezinto ezikhiqize izinga elinjalo le-ripple, kuyacaca ukuthi kwaba ukuzamazama komhlaba okwabangela ukuba ama-cubic metres ayizigidi ezingu-30 ezinto ezibonakalayo aphule iqhwa. Futhi, indawo yokungena echwebeni incane kakhulu, okusho ukuthi amanzi amaningi empeleni avalelwe phakathi kwezintaba. Le ndawo inomkhuba wemvelo wokubangela amagagasi amakhulu, kungaba ngokudilika kwenhlabathi noma ukuzamazama komhlaba.
Ucwaningo lwango-2010 lwaphetha ngokuthi isenzakalo "se-double slide" sasingenzeka kakhulu: i-rockslide yashaya eduze kwekhanda le-Lituya Glacier, okwenza ukuba cishe ama-cubic metres angu-400 eqhwa aphule umunwe wangaphambili weqhwa, futhi mhlawumbe nomjovo omkhulu. kwamanzi ngaphansi kweqhwa. Iqhwa elikhanyayo liyakhuphuka ngaphambi kokuba licwile, futhi inani elikhulu lokugcwaliswa okuvalelekile (i-subglacial kanye ne-preglacial sediments) elivalelwe ngaphansi kweqhwa futhi laxegiswa ukuzamazama komhlaba licishe likhululwe ngokushesha njengenguquko yesibili, enkulu.
I-tsunami enkulu kunazo zonke emhlabeni nezinguzunga zeqhwa ezincibilikayo
Ososayensi bachaza imiphumela yokuncibilika. I-Alaska inezinguzunga zeqhwa ezinkulu kunazo zonke emhlabeni, ezingaba ugqinsi olungaphezu kwekhilomitha futhi zimboze amakhulu ngamakhulu amakhilomitha-skwele. Isisindo seqhwa sibangela ukuba izwe licwile, futhi lapho izinguzunga zeqhwa zincibilika, umhlabathi uyaphakama futhi, njengesipontshi esingakwazi ukumpintshana. Kwenzeka lokhu nje ukufudumala kwembulunga yonke kubangela ukulahleka kweqhwa, ngakho ukuphakama komhlaba kuyisenzakalo esivame kakhulu kunasemakhulwini eminyaka ngaphambi kweNguquko Yezimboni.
Ukuphakama kwendawo kunezingxenye ezimbili. Ngakolunye uhlangothi, kukhona lokho ochwepheshe abakubiza ngokuthi "umphumela we-elastic", okwenzeka lapho umhlabathi uphakama futhi ngokushesha ngemva kokunyamalala kweqhwa elicindezela ngesisindo salo. Ngakolunye uhlangothi, kukhona lokho okubizwa ngokuthi "umphumela we-mantle", obese ugeleza ubuyele esifundeni ukuze uvule indawo.
Abacwaningi bathole ukuxhumana phakathi kokunyakaza kwengubo yokusabalalisa nokuzamazama komhlaba okukhulu eningizimu-mpumalanga ye-Alaska, lapho Sekuyiminyaka engaphezu kwengu-200 izinguzunga zeqhwa zincibilika. I-Southern Alaska itholakala lapho kuhlangana khona i-continental plate yaseNyakatho Melika kanye ne-Pacific plate. Lezi zingcwecwe zinyakaza ngesilinganiso esingaba amasentimitha amahlanu ngonyaka, okubangela ukuzamazama komhlaba njalo.
Ngithemba ukuthi ngalolu lwazi ungafunda kabanzi mayelana ne-tsunami enkulu kunazo zonke emhlabeni nezici zayo.