Yini i-megatsunami

Un i-megatsunami igagasi elikhulu kakhulu elidalwe ukunyakaza okukhulu nokuzumayo kwempahla emzimbeni wamanzi. Ososayensi bayesaba ukwenzeka kwalolu hlobo lwesimo ngenxa yomthamo omkhulu wokucekela phansi izindawo ezisogwini.

Ngalesi sizathu, sizonikezela lesi sihloko ukuze sikutshele ukuthi iyini i-megatsunami, yiziphi izici zayo, imiphumela kanye namathuba okuba ivele.

Yini i-megatsunami

I-Megatsunami inezici ezihluke ngokuphelele kunezinye izinhlobo ezivame kakhulu zama-tsunami. Ama-tsunami amaningi endabuko abangelwa umsebenzi we-tectonic waphansi olwandle (ukunyakaza kwezingcwecwe zomhlaba) futhi ngaleyo ndlela enzeka emngceleni wamapuleti futhi awumphumela wokuzamazama komhlaba kanye nokuphakama noma ukwehla komhlaba wolwandle, okubangela ukususwa kwamanzi.

Ama-tsunami avamile abonisa amagagasi angashoni olwandle, futhi njengoba ulwandle luba mnyama futhi lusondela emhlabathini, amanzi aqala "ukuhlanganisana" abe ukuphakama kwamagagasi afinyelela kumamitha angaba ngu-10. Esikhundleni salokho, ama-tsunami amakhulu enzeka lapho inani elikhulu lempahla liwela ngokuzumayo emanzini noma eduze namanzi (isibonelo, kusuka kumthelela we-meteorite noma umsebenzi wentaba-mlilo).

Bangaba nokuphakama kwamagagasi amakhulu kakhulu, kusukela kumakhulu amamitha futhi ngokunokwenzeka izinkulungwane zamamitha, ezedlula kude noma iyiphi i-tsunami evamile. Lezi zindawo eziphakeme zamagagasi zenzeka lapho amanzi "efafazwa" futhi eshaywa umthelela noma ukususwa.

Izibonelo zama-tsunami ama-mega esimanje zifaka lawo ahlotshaniswa nokuqhuma kwe-Krakatoa yango-1883 (ukuqhuma kwentaba-mlilo), i-Lituya Bay mega tsunami yango-1958 (imfucumfucu igelezela echwebeni), namagagasi abangwe ukudilika kwedamu. de Ouyote (umsebenzi womuntu uphazamise izinhlangothi zombili izinga lolwandle (isigodi). Izibonelo zangaphambi komlando zifaka ukudilika komhlaba kwe-Storegga (ukudilika komhlaba) kanye nomthelela we-Chicxulub, Chesapeake Bay, kanye ne-Eltanin meteorite.

Yenzeka kanjani i-megatsunami?

I-tsunami enkulu iyi-tsunami ene-amplitude yokuqala (ubude) elinganiswa ngamashumi, amakhulu, noma izinkulungwane zamamitha. Ama-tsunami amakhulu ayizigaba ezahlukene zezenzakalo kunama-tsunami endabuko futhi abangelwa izindlela ezahlukene.

Ama-tsunami avamile awumphumela wokunyakaza kwephansi lolwandle ngenxa ye-plate tectonics.. Ukuzamazama komhlaba okunamandla kungabangela ukuba indawo engaphansi kolwandle inyakaze amashumi amamitha, okusenganyakazisa insika yamanzi ngaphezulu, kubangele ukuba kwakheke ama-tsunami. Ama-tsunami endabuko anobude obuncane begagasi olwandle futhi ngokuvamile awabonwa olwandle, anokuvuvukala okuncane kuphela ngohlelo lwama-30 cm (12 in) ngaphezu kwendawo evamile yolwandle.

emanzini ajulile, i-tsunami ingadlula ngaphansi komkhumbi ngaphandle kokuthi abasebenzi babone. Lapho ifika ezweni, ukuphakama kwegagasi kwe-tsunami yendabuko kukhula kakhulu njengoba indawo engaphansi olwandle itshekela phezulu futhi ingaphansi legagasi liphushela ikholomu yamanzi phezulu. Ama-tsunami endabuko, ngisho nalawo ahlotshaniswa nokuzamazama komhlaba okunamandla kakhulu, awafinyeleli ubude obungaphezu kwamamitha angama-30.

Ngokuphambene, ama-tsunami amakhulu abangelwa ukudilika komhlaba okukhulu nezinye izenzakalo ezithinta amanzi amaningi. Lokhu kuhlanganisa nendaba yama-meteor ashaya olwandle. Ukuzamazama komhlaba ngaphansi kolwandle noma ukuqhuma kwentaba-mlilo akuvamisile ukukhiqiza ama-tsunami amakhulu kangako, kodwa ukudilika kwenhlabathi okubangelwa ukuzamazama komhlaba eduze nemithombo yamanzi kwenza ngoba kubangela ukufuduka okukhulu. Uma ukudilika komhlaba noma ukushaqeka kwenzeka emanzini alinganiselwe, njengoba kwenzeka e-Vajont Dam (1963) nase-Lituya Bay (1958), amanzi angase angahlakazeki futhi igagasi elilodwa noma ngaphezulu angase abe makhulu kakhulu.

Enye indlela yokubona umehluko ukuthi ama-tsunami avamile abangelwa izinguquko olwandle., njengokuphusha phansi kwebhakede elikhulu lamanzi lize ligcwale, okwenza amanzi "ashelele" nhlangothi zombili. Kulo mfanekiso, i-tsunami enkulu ifana nokuwisa itshe elikhulu kwelinye icala likabhavu lisuka endaweni ephakeme kakhulu, libangele ukuthi amanzi agcwale futhi aphuphume ngakolunye uhlangothi.

Ngezinye izikhathi ama-tsunami amakhulu abizwa ngokuthi izindawo ezimbili eziphakeme: ukuphakama kwegagasi ngokwalo (emanzini avulekile) nokuphakama kokukhuphuka kwalo lapho lifika emhlabeni, okungaba phezulu izikhathi eziningana kuye ngendawo.

Imiphumela kanye nengozi

Ocwaningweni olwethulwa yi-Tsunami Society ngo-1999, kwahlaziywa izindlela ezadala i-tsunami enkulu yomcimbi we-Litua Bay. Imodeli yathuthukiswa kakhulu futhi yashintshwa ocwaningweni lwesibili ngo-2010.

Nakuba ukuzamazama komhlaba okubangele i-tsunami enkulu kukholakala ukuthi bekunamandla amakhulu, kungase kungabi ukuphela komnikeli ngokusekelwe ekulinganisweni kokuphakama kwamagagasi. Ukugeleza kwamanzi echibini, ukudilika kwenhlabathi, noma ukuzamazama komhlaba ngokwako akuzange kubangele i-tsunami enkulu eyabonwa, nakuba lezi kungenzeka zaziyimbangela.

Kunalokho, ama-tsunami amakhulu abangelwa inhlanganisela yezenzakalo ezilandelanayo ngokushesha. Isehlakalo esikhulu size ngendlela yokushaqeka okukhulu okuvele kungazelelwe, lapho ama-cubicyards ayizigidi ezingama-40 edwala elingamakhulu amamitha ngaphezu kwetheku ephihlizwa ukuzamazama komhlaba futhi "cishe ngokuphelele" asuswa ethambekeni. I-rockfall iphinde yabangela ukuthi umoya "ungene" ngenxa yemiphumela ye-viscous, eyandisa inani lokufuduka futhi yaphinde yathinta i-sediments engaphansi kwe-bay, okwenza i-crater enkulu. Ucwaningo luphethe ngokuthi:

• Igagasi elingamamitha angu-524 (amamitha angu-1,720) ekhanda lechweba ngoJulayi 9, 1958., namagagasi alandelayo ahambisana nengxenye enkulu ye-Lituya Bay, ngokuyinhloko ayebangelwa ukushelela kwedwala okukhulu. Amatshe e-Gilbert Bay enhloko ye-Lituya Bay, ebangelwa ukunyakaza komhlaba okuguquguqukayo eduze kwe-Fairweather Fault.

Ngithemba ukuthi ngalolu lwazi ungafunda kabanzi mayelana ne-megatsunami nezici zayo.