During this eruption 2007 a caldera collapse occurred at the volcano.
en.wikipedia.org The caldera is known to have erupted in 1896, 1906, 1915, 1934, 1946, 1952-1953, 1954, 1955, 1957, 1958, 1959, and 1960.
en.wikipedia.org Violent Pleistocene eruptions produced two ignimbrite fans stretching west to the coast, and a 6 km by 9 km caldera.
en.wikipedia.org After the last caldera-forming eruption 23,000 years ago several smaller vents within and around the caldera have seen eruptive activity.
en.wikipedia.org The volcano was considered to be an irregular shaped of caldera, but evidence about caldera is problematical.
en.wikipedia.org