alaska united_states miles anchorage located comprises land mass island small glaciers northwest southeast volcano miles miles base possessing southern crater far greater size feet wide attributed failure southern wall northern crater enclosed discovery accessibility prominent sailor russia successful expeditions sent explore area pacific soon settled started settlement built additional vessels dubbed company started north_america stalled storm delayed forced land storm coast storm proved powerful ships turned way charting including barely studied resulting knowledge possibly episodes managed geography geology northernmost volcano composed older covered lava flows running northwest southern coasts northern crater small feature suggesting dome collapse northwest flank southern flank higher considerably larger contains activity created eruption runs southern summit volcano steep sea cliffs southwest island cut older masses offshore island produced debris flows volcano lava flows origin main episodes contributed creation lava deposits mountain vary feet feet thickness extend external volcano suggesting activity pleistocene took place large lava valleys island southwest shaped oldest flows pleistocene age composed smaller amounts rock rock makes volcano estimated pleistocene age factors contribute mainly presence glaciers failure landslide debris rock comprises lava flows masses shaped glacial retreat began years past newly formed rocks landslides generated north east flanks volcano mapping alaska volcano observatory proceeded map volcano surrounding area addition implementing seismic monitors june history extensive history dating occurred summit accompanied lava flows typically characterized central vent eruption followed explosive eruption explosion index occurred april january august january september august uncertain occurred underwent major explosive eruption generated lava flows volcanic glass red tone thirteen located contributed episode likely eruption flows convened suggested deposits streamed summit 1980s 1990s august erupted time records sending ash feet atmosphere precursor earthquakes occurred august west seismic network similar episode took place ash cloud exceeding feet appeared satellite images january marked milestone history flow likely volcanic origin observed commercial airplane pilot mass extended feet volcano steam reportedly volcano unable verify eruption employee fish wildlife service spotted ash covering climbing feet summit august minor eruption occurred september reported nearby anchorage consisting ash steam rose feet volcano summit threat volcanic hazards pose significant threat human life near unexpectedly ash clouds falling volcanic ash flows debris easily span deadly hazards volcanic ash induce engine failure puts commercial particular high risk volcanic ash known creates respiratory eye flows eruption destroy wildlife volcano historically produced flows travel extremely fast future flows travel island pacific_ocean large fall ocean generate unlikely
Gareloi Volcano