SHōWA-SHINZAN (昭和新山, Shōwa-shinzan) is a volcanic lava dome
Shikotsu-Toya National Park ,
* 1.1 Phase 1, Pre-Eruption Phase (28 December 1943 – 22 June 1944) * 1.2 Phase 2, Eruption Phase (23 June 1944 – 31 October 1944) * 1.3 Phase 3, Post Eruption Phase (1 November 1944 – September 1945)
* 2 See also * 3 References
VOLCANIC ACTIVITY TIMELINE
PHASE 1, PRE-ERUPTION PHASE (28 DECEMBER 1943 – 22 JUNE 1944)
On 28 December 1943, earthquakes starting to occur frequently around Mount Usu, with occurrences of more than 200 times per day on some days. The hypocenter in the early days was located in the vicinity of Lake Tōya. As the year entered 1944, the hypocenter started to move toward the eastern part of the base of Mount Usu and this resulted in the protuberance of the overlying ground. Eventually the protuberance started to spread to the north, reaching up to heights of 50 meters in some areas. The Sōbetsu riverbed also started to rise, and many fissures started to appear in the surrounding farmlands. The longest fissure recorded was about 600 meters long. On 22 June 1944, there were about 250 earthquakes in one day, and accordingly the protuberance of the ground rose by 150 centimeters in one day.
PHASE 2, ERUPTION PHASE (23 JUNE 1944 – 31 OCTOBER 1944)
On 23 June 1944 at 0815 hours, smoke started to come out of the fissures and shortly after a huge eruption followed accompanied by a thunderous roar. On 2 July 1944, the eruption became even more vigorous, and a phreatomagmatic eruption occurred. On 7 July 1944, a pyroclastic surge accompanied the eruption. The surge managed to reach the northern bank of Lake Tōya, burning forests and houses in the process. By the end of October 1944, Masao Mimatsu recorded a total of seven craters, seventeen major eruptions and countless minor ones. Furthermore, centimeters of volcanic ash from the eruption had been found deposited up to one kilometer way from the volcano, while the protuberance of the ground continued. From July 1944 to August 1944, the protuberance grew by two meters on some days.
PHASE 3, POST ERUPTION PHASE (1 NOVEMBER 1944 – SEPTEMBER 1945)
Within this phase all eruption activity stopped completely and a lava
dome began to take shape. The lava dome continued to take shape until
September 1945, when earthquake activity finally seemed to come to a
halt. The birth of
Wikimedia Commons has media related to SHOWASHINZAN .
* ^ A B
Geographical Survey Institute
Global Volcanism Program
* WorldCat Identities * VIAF : 254474705 * NDL