A daren 9 ga Yuli, 1958, Lituya Bay na Alaska ya sha wahala daya daga cikin abubuwan ban mamaki a cikin ƙwaƙwalwar rayuwa. Girgizar kasa mai karfin awo 7,9 a ma'aunin Richter ta afku a gabar tekun baki daya. Matsalar ba ita ce girgizar kasa kadai ba, har ma da raƙuman ruwa da ta haifar, sama da rabin kilomita. Guguwar ruwa mafi girma a tarihin da aka rubuta. An kafa ni tsunami mafi girma a duniya sani har yau.
A cikin wannan labarin, za mu gaya muku duk abin da kuke buƙatar sani game da tsunami mafi girma a duniya, halayensa da barnar da ya haifar.
Tsunami mafi girma a duniya
Fault na Fairweather yana kusa da Lituya Bay a Alaska. Don haka, yanki ne na ayyukan girgizar ƙasa, inda ɗaya ko wata girgizar ƙasa mai girman gaske ke faruwa a cikin 'yan shekarun da suka gabata. Koyaya, wanda daga 1958 yana da girma musamman. Ban da haka, an ƙara wani muhimmin abu: dutsen da ya ƙare a cikin ruwa kuma ya haifar da raƙuman ruwa da ba a taɓa gani ba.
An kiyasta cewa mita 30 na dutsen ya fado daga tsayin kusan mita 900. Wannan mahaukacin dutsen bai yi komai ba sai haifar da manyan raƙuman ruwa. Kodayake babu fayilolin hoto na wannan lokacin ko kayan aikin da za su iya yin rikodin shi, akwai shaida daga baya. Shekaru goma bayan haka, lokacin da ragowar lalacewar igiyar ruwa har yanzu ana iya gani, muna samun shaida. Wani bincike da aka yi a shekara ta 2010 na wani tudu da ke kusa ya nuna canje-canje a cikin ciyayi da aka yi ta. A kusan tsayin mita 500, akwai muhimmin canji na ciyayi masu ƙanana fiye da na sama. Masana ilimin kasa da masu bincike sun yi kiyasin cewa raƙuman ruwa na iya kaiwa tsayin mita 524.
Ƙoƙarin rage cutarwa
Rufewar dangi na Lituya Bay bai taimaka wajen rage bala'i ba. Kamar sarari na ruwa da ke kewaye da ƙasa, igiyar ruwa tana kwashe duk abin da ke kusa da shi, haka kuma, ya sa ya fi tsayi ta hanyar raguwa a gefen. Yana da girma haka ta mamaye ƙasar da ke kewaye kuma a ƙarshe ta zube cikin Tekun Alaska.
Mazauna mafi girma a lokacin ita ce Yakutat, wanda ya sami matsakaicin lalacewa idan aka yi la'akari da girman girgizar kasa da girman raƙuman ruwa. An san cewa jimillar mutane uku ne suka mutu a tsibirin Yakutat mai tazarar kilomita 200 daga gabar tekun, saboda an binne wasu daga cikinsu a cikin teku. Komawa bakin tekun, wasu mutane biyu da ke cikin kwale-kwalen kamun kifi su ma sun tafi da su.
Yankin wani yanki ne na Glacier Bay National Park and Preserve, don haka yankin da ke kewaye ba kowa ba ne, amma kwale-kwalen kamun kifi guda uku ne a cikin tekun lokacin da girgizar kasar ta afku. Jirgin ruwan Vivian da Bill Swanson Badger an kai shi cikin bakin bakin teku ta raƙuman ruwa "yana zamewa a kudancin Alaska" kuma daga ƙarshe ya nutse. An yi sa'a, wani jirgin ruwa ya ceci auren. Howard Uhlrich da ɗansa ɗan shekara 7 sun yi nasarar kauce wa igiyar ruwa tare da jirginsu Edrie, inda suka nufi wajensu. Amma Orville Wagner da matarsa sun mutu sakamakon bangon ruwa a cikin jirgin Somermore.
A garin Yakutat, matsugunin dindindin na dindindin da ke kusa da cibiyar a lokacin, an lalata ababen more rayuwa kamar gadoji, tashar jiragen ruwa da bututun mai. Wata hasumiya ta ruguje kuma wani katafaren gida ya lalace ba a iya gyara shi ba. Yashin yashi da fissure sun bayyana a gabar tekun kudu maso gabas, kuma igiyoyin karkashin teku da ke goyon bayan tsarin sadarwar Alaska sun katse.
Guguwar igiyar ruwan tsunami mafi girma a duniya ta haifar da illa ga ciyayi da ke kewayen yankin da dutsen ya fado mai tsayin mita 520, da kuma bakin tekun.
seismic geology
Abin da ya faru a Lituya wani abu ne na abin da ake kira giant tsunami. Raƙuman ruwa sama da mita 100 ne kawai ke shiga cikin wannan rukunin. Yankin Alaska inda girgizar kasar ta faru yana kan layin kuskure wanda motsi ya haifar da girgizar kasa mai girma. Yankin Lituya Bay yana da tarihin abubuwan da suka faru na tsunami, amma eLamarin na 1958 shine na farko da aka yi rikodin tare da isassun bayanai.
Duk da yake har yanzu ana muhawara game da menene haɗuwa da abubuwan da suka haifar da irin wannan matakin, a bayyane yake cewa Girgizar kasar ce ta yi sanadin karyewar glacir mita miliyan 30 na abubuwa. Har ila yau, hanyar shiga bakin ruwa kadan ne, wanda ke nufin cewa a zahiri an rufe wani babban ruwa a tsakanin tsaunuka. Wannan filin yana da dabi'a ta asali don haifar da manyan raƙuman ruwa, ko dai ta hanyar zaftarewar ƙasa ko girgizar ƙasa.
Wani bincike da aka gudanar a shekara ta 2010 ya tabbatar da cewa wani lamari na “slide biyu” ya fi yuwuwa: zaftarewar dutse ta afka kusa da kan glacier na Lituya, wanda ya haifar da wasu cubic mita 400 na kankara ya karye yatsan gaban glacier, kuma mai yiwuwa an yi babbar allura. na ruwa a karkashin glacier. Gilashin da aka haska yana tasowa kafin ya nutse, kuma babban adadin da aka kama (subglacial da preglacial sediments) wanda aka makale a ƙarƙashin glacier kuma girgizar ƙasa ta saki kusan nan da nan an sake shi a matsayin canji na biyu mafi girma.
Tsunami mafi girma a duniya da glaciers mai narkewa
Masana kimiyya sun bayyana sakamakon narkewa. Alaska na da wasu manyan glaciers a duniya, wanda kauri zai iya kai fiye da kilomita daya kuma ya mamaye daruruwan kilomita murabba'i. Nauyin ƙanƙara yana sa ƙasar ta nutse, kuma idan dusar ƙanƙara ta narke, ƙasa ta sake tashi, kamar babu soso mai matsi. Haka ya faru cewa dumamar yanayi yana haifar da asarar kankara, don haka tasowar duniya wani lamari ne da ya zama ruwan dare fiye da a shekarun da suka gabata kafin juyin juya halin masana'antu.
Hawan filin yana da abubuwa biyu. A gefe guda kuma, akwai abin da masana ke kira "Elastic Effect", wanda ke faruwa a lokacin da ƙasa ta sake tashi nan da nan bayan wani shingen ƙanƙara da ke dannawa da nauyinsa ya ɓace. A gefe guda kuma, akwai abin da ake kira terrestrial "mantle effect", wanda sai ya koma cikin yankin don samar da sarari.
Masu bincike sun gano wata alaƙa tsakanin alkyabbar yaɗa motsi da kuma wata babbar girgizar ƙasa a kudu maso gabashin Alaska, inda glaciers suna narkewa sama da shekaru 200. Kudancin Alaska yana a mahadar farantin nahiyoyin Arewacin Amurka da farantin Pacific. Wadannan faranti suna tafiya da juna a kusan santimita biyar a kowace shekara, suna haifar da girgizar kasa akai-akai.
Ina fatan da wannan bayanin zaku iya ƙarin koyo game da tsunami mafi girma a duniya da halayensa.