The Summit of Mount Etna Prior to the 1971 Eruptions [and Discussion]

摘要: The summit cone of Mt Etna is cut by an approximately NNE-SSW trending, narrow fissure zone that controls much the terminal activity this volcano. Within central crater, which lies at top cone, there are two main vents alined on zone: chasm, a deep pit; and 1964 crater. Both these were blocked before 1971. NE crater first opened in 1911 lower slopes same zone, has had open conduit from lava been erupted constant rate 1966 to beginning 1971 eruption. In 1968 small gas bocca known as Bocca Nuova near previously lavas 1956. collapsed early 1970 give 100 m wide It suggested collapse resulted movement magma depth into 1956 causing sudden lowering column below Bocca, continued migration eventually lead eruption April 1971, site being line with fissure. A rise temperature fumaroles edge after attributed incursion across