Nnyocha ndị mbụ e mere na 1946 gosiri na ọwụwa anyanwụ nwere ihe ruru mita 200 (656 ụkwụ) miri emi na geology nke ugwu mgbawa. Ọdịda anyanwụ nwere oke omimi nke mita 140 (459 ụkwụ) na geology nke mejupụtara ọtụtụ nkume sedimentary nke oge Neogene. A họọrọ ọwụwa anyanwụ, na ọnọdụ ya dị mma maka tunneling. Geology nke akụkụ ala nke ọwara ahụ gụnyere ugwu mgbawa, nkume pyroclastic, na nkume sedimentary nke oge ahụ. Mpaghara mbụ dị n'okpuru Tsugaru Strait nwere ọwụwa anyanwụ na ọdịda anyanwụ, ha abụọ dị ihe dị ka kilomita 20 (12 mi). Nnyocha mbụ e mere na 1946 gosiri na ọwara ọwụwa anyanwụ ruru mita 200 (656 ụkwụ) miri emi na geology nke ugwu mgbawa.
Ihe dị ka 200