El INtaba i-Saint Helena yintaba-mlilo eqhumayo kuMntla Merika, inyuka ngokumangalisayo kumzantsi-ntshona welizwana laseWashington eUnited States. Igama layo lesiNgesi yiSt. Helens, kwaye amaqela oMthonyama waseMelika ayibiza njengeLawetlat'la, Lawalaclough, kunye neTahonelatclah. Igama layo langoku livela ku-Elaine Fitzherbert, u-XNUMXst Baron waseSaint Helena kunye nomhlobo womhloli uGeorge Vancouver, owaphonononga le ndawo xa yayisaziwa kancinci.
Kweli nqaku siza kukuxelela zonke iimpawu, imvelaphi, i-geology kunye nogqabhuko-dubulo lweNtaba i-Saint Helena.
Ubicación
IMount Saint Helens yindawo eyaziwayo yokwakhiwa kwentaba-mlilo ekhoyo kwiScamania County, kwiLizwana laseWashington, kwiPasifiki ekuMntla ntshona woMmandla waseUnited States of America. Malunga neemitha ezingama-2.550 ngaphezu komphakamo wolwandle, kusetyenziswe igama elithi “current” ngenxa yokuba ugqabhuko-dubulo lwalo olubhalwe ngokubanzi lwehlise umphakamo wesi sakhiwo sentaba-mlilo.
Imi malunga neekhilomitha ezili-154 ukusuka eSeattle kwaye malunga neekhilomitha ezingama-85 kumntla-ntshona wePortland, Oregon. Esi sakhiwo sikhulu sentaba-mlilo siyinxalenye yeCascade Range, kwaye indawo yayisaziwa ngegama elithi Louwala-Clough, elithetha "intaba-mlilo eqhumayo okanye intaba," ngolwimi olubizwa ngokuba ngabantu basekhaya abadumileyo, isizwe sasekhaya esibizwa ngokuba yiKlickitat.
I-Saint Helena ifumana igama layo kunozakuzaku u-Erin Fitzherbert, kuba wayeyiBaron yokuqala yaseSaint Helena, umhlobo omkhulu wommi waseGeorge Vancouver, umkhenkethi omkhulu nonomdla owayephethe umsebenzi wokuhlola indawo yenkulungwane yeshumi elinesibhozo eSanta Helena. Intaba-mlilo yaziwa ngogqabhuko-dubulo olukhulu oluqulathe izixa ezikhulu zothuthu kunye nento ebizwa ngokuba yi-pyroclastic flows.
Ukusekwa kweMount Saint Helens
Xa kuthelekiswa nezinye iintaba-mlilo kwiCascade Range, iMount Saint Helens yintaba-mlilo esencinane. Ngokutsho kweUnited States Geological Survey (USGS), ukusekwa kwayo Yenzeka kwizigaba ezi-4 zogqabhuko-dubulo olwaqala malunga nama-275.000 eminyaka eyadlulayo. nangona i-Smithsonian Institution Global Volcanic Activity Programme ibonisa ukuba yaqala ngezigaba ze-9 ezenziwe nge-40.000-50.000 kwiminyaka edlulileyo ngexesha lokuqhuma. Ngayiphi na imeko, ngexesha leHolocene yayiyeyona isebenzayo kuzo zonke iintaba-mlilo zaseCordillera.
INkqubo yeeNgozi zeVolcanic ye-USGS ibonisa ukuba ibekwe kufutshane nendawo yokuthotywa kwepleyiti yeJuan de Fuca kunxweme olusentshona eUnited States kwaye sisiphumo sokushukuma okukhulu koqweqwe loMhlaba.
Kwiminyaka engama-12.800 XNUMX eyadlulayo, ikona yamandulo yeNtaba iSt. Helens. yenziwe kugqabhuko-dubulo lwentaba-mlilo, iidomes ze-lava, kunye nokunye ukuhamba kwe-pyroclastic eyayifikelela kumazwe akude ukusuka ezantsi kwentaba-mlilo. Kwiminyaka engama-3000 edlulileyo, i-cone ifumene isakhiwo sanamhlanje. Ngokwenxalenye yayo, i-Global Volcanism Programme ikhankanya ukuba ikhowuni yenziwa ngokukhutshwa kwelava kunye ne-pyroclastic imathiriyeli ngaphambi kweminyaka engama-2200 eyadlulayo, ngelixa ikhowuni yanamhlanje ikukuqhubeka kwe-andesite, i-dacite, kunye namaqhekeza e-basalt aphuma ekuphumeni.
Ugqabhuko-dubulo lweNtaba iSaint Helens
Ugqabhuko-dubulo lowe-1980 lwalulolona gqabhuko-dubulo lwenkulungwane yama-2340, kodwa iintaba-mlilo zinembali ende yogqabhuko-dubulo. Isiganeko esidala esiqinisekisiweyo senzeke ngo-1860 BC. C. Olunye ugqabhuko-dubulo lwenzeka ngowe-1180a. C, 1110. C, 100a. C, 420 BC C, AD 1831 C, ngoAgasti 26, Matshi 1847, 27, Matshi 1980, 5, Novemba 1990, 1, no-Oktobha 2004, XNUMX.
Itotali yokuqhuma kwe-40 kuye kwaqinisekiswa ngokuhamba kwexesha, kunye nokungaqiniseki okuthile. Kwabakho inyikima phantsi kwentaba-mlilo ngoMatshi 20, 1980, kwaza kwabakho ezinye iinyikima ezazingamandla kangako phakathi komhla wama-20 nowama-27 kwaloo nyanga inye. Kanye emini emaqanda ngomhla wama-27, intsika yothuthu nomphunga yaphuma entabeni, yafikelela kubude obuziimitha ezili-1.829. Kodwa eyona nto imbi kakhulu ayizange yenzeke.
Ngentsasa ye-18 kaMeyi, inyikima ye-5.1 yenzeke kwaye inxalenye esemantla yentaba-mlilo yaqala ukuwa. kwenzeka ntoni ukudilika komhlaba kunye nokudubula kwePliny iiyure ezili-9. Ikholamu yokuqhuma yayiziikhilomitha ezingama-24 ukuphakama kwaye uthuthu lwachukumisa iindawo ze-11 zase-US. Ibhalansi i-57 ifile (kuquka umfoti kunye nejografi) kunye nezigidi zeedola kumonakalo wezoqoqosho.
ugqabhuko-dubulo lokugqibela
Kunokuthiwa yonke into yaqala ngokuthe ngqo ngo-Matshi 16, ngakumbi ngo-1980, yayinesiqalo esikhethekileyo, mhlawumbi uthotho lweenyikima, imvelaphi yayo ibonakala ikwintshukumo enkulu ye-magma equlethwe kwintaba yaseSanta Elena. Iinyikima ezinzulu ezihambelana nesenzeko sobukhulu be-4,2 kwisikali se-Richter sinokubhaliswa ngolu hlobo ngo-Matshi 20, ukugcina ummandla wexesha elifanelekileyo kunye nomgangatho, njengalowo we-Pacific Ocean, ephawulwe ngo-15:47.
Konke oku kulele ngaphantsi komphezulu wentaba ekhankanywe ngasentla yeNtaba yaseSt. umsebenzi wale ntaba-mlilo inkulu emva kweminyaka engaphezu kwe-123 ingasebenzi.
Kuthiwa emva kolu ngcelele lweenyikima ezincinane zongezwa yaye ngandlel’ ithile zonke ii<em>seismometers ezifakwe ngokuchanekileyo zahluzwa ngexesha lokusasazwa kwendawo yonke, de kwafikelela umlinganiselo omkhulu phakathi koMatshi 25 kunye neentsuku ezimbini kamva, ebudeni bezi ntsuku zimbini zixakeke kakhulu.
Inani elikhulu leenyikima ze-174 zabhalwa kwiinyikima ezidumileyo ze-2,6 kwisikali sikaRichter okanye ngaphezulu. Kwakusemva koku iinyikima zanda ngomlinganiselo we-3.2 degrees yaye zazisanda phakathi kuka-Aprili noMeyi, ekuqaleni kuka-Aprili, ngenxa yesizathu esithile, kwakukho umlinganiselo weenyikima zomhlaba ezi-5 ezimalunga nesi-4 okanye ngaphezulu suku ngalunye.
Kodwa kwiveki engaphambi koko, nge-18 kaMeyi, umyinge wawujikeleza kudederhu lweenyikima ezingama-55 ngosuku, ekuqaleni kungekho ngqiqweni okanye ubungqina obuthe ngqo bogqabhuko-dubulo lwexesha elizayo, kodwa uhlobo oluthile lwenyikima encinane ebangela enkulu. Njengoko kubonisiwe ngasentla, ikhephu kunye nomkhenkce eziqokelelweyo eziqatshelweyo emoyeni. Ngentsimbi ye-12:36 emva kwemini ngoMatshi 27, kwabakho ugqabhuko-dubulo olwehlayo, yaye abantu abaninzi bathi lwenzeka kabini ngaxeshanye.
Ndiyathemba ukuba ngolu lwazi unokufunda ngakumbi malunga neNtaba iSaint Helena kunye neempawu zayo.