Rịba ama amaokwu a dị n'okpuru ma zaa ajụjụ ahụ mgbe e mesịrị n'otu asụsụ ahụ dị ka amaokwu ahụ:  Ebe e si agafe: A malitere ime nnyocha n'afọ 1946, a malitekwara iwu ya n'afọ 1971. Ka ọ na-erule August 1982, ihe na-erughị mita 700 nke ọwara ahụ ka ga-egwu. Mbụ kọntaktị n'etiti abụọ n'akụkụ bụ na 1983.The Tsugaru Strait nwere ọwụwa anyanwụ na n'ebe ọdịda anyanwụ n'olu, ma ihe dị ka 20 km (12 mi) n'obosara. Nnyocha ndị mbụ e mere na 1946 gosiri na ọwụwa anyanwụ nke ọkpụkpụ ahụ ruru mita 200 (656 ụkwụ) nke dị omimi na geology nke ugwu mgbawa. Akụkụ ọdịda anyanwụ nwere oke omimi nke mita 140 (459 ụkwụ) na geology nke mejupụtara ọtụtụ nkume sedimentary nke oge Neogene. A họọrọ ọnụ ọnụ ọdịda anyanwụ, na ọnọdụ ya nke a na-ewere dị ka ihe dị mma maka tunneling. Geology nke akụkụ mmiri nke ọwara ahụ bụ nkume mgbawa, nkume pyroclastic, na nkume sedimentary nke oge Neogene. Mpaghara a na-agbagọ n'ime ihe fọrọ nke nta ka ọ bụrụ nke kwụ ọtọ, nke pụtara na okwute nke kacha bụrụ nwata nọ n'etiti ọwara mmiri ahụ ma zute ikpeazụ. E kewara ihe dị ka ụzọ atọ, akụkụ Honshū nwere okwute mgbawa ugwu (andesite, basalt wdg); akụkụ Hokkaido nwere okwute sedimentary (tuff oge nke atọ, mudstone, wdg); na akụkụ etiti nwere Kuromatsunai strata (oge nke atọ dị ka ájá ájá). Igneous intrusions na mmebi kpatara mkpakọ nke nkume na mgbagwoju anya tunneling usoro. Mbụ geological nnyocha mere si 1946 na 1963, nke gụnyere mkpọpu ala oké osimiri, sonic nnyocha ndị e mere, mmiri n'okpuru osimiri mkpọpu ala, observations iji a mini-n'okpuru osimiri, na seismic na magnetik nnyocha ndị e mere. Iji mee ka a ghọtakwuo ihe, a na-eme ihe ngosi nke ụgbọ mmiri na-aga n'ihu n'ihu n'ihu n'akụkụ nke ọrụ na isi ọwara. E gwuru olulu ahụ n'otu oge site n'ebe ugwu na n'ebe ndịda. E ji usoro ọdịnala nke igwu olulu n'ugwu mee ihe n'akụkụ ala akọrọ, nke nwere nanị otu olulu isi. Otú ọ dị, n'akụkụ nke dị kilomita 23.3 n'okpuru oké osimiri, e gwuru olulu atọ ndị dayameta ha na-arịwanye elu n'otu n'otu: olulu mbụ e ji eme nnyocha, olulu ọrụ, na n'ikpeazụ, olulu isi. A na-ejikọta ọwara ọrụ ahụ na isi...  Ajụjụ: Nkume dị aṅaa dị na Western Neck ka a na-ahụ na nsọtụ ya?
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