Suwanose-jima The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network. Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source. -------------------------------------------------------------------------------- SUWANOSE-JIMA Ryukyu Islands, Japan 29.53°N, 129.72°E; summit elev. 799 m; All times are local (= UTC + 9 hours) Background. The 8-km-long, spindle-shaped island of Suwanose-jima in the northern Ryukyu Islands is occupied by a stratovolcano with two historically active summit craters. Only about 50 persons live on the sparsely populated island. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanose-jima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from On-take, the NE summit crater, that began in 1949 and lasted nearly a half century. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, after which the island was uninhabited for about 70 years. The SW crater produced lava flows that reached the western coast in 1813, and lava flows reached the eastern coast of the island in 1884. Suwanose-jima Information from the Global Volcanism Program -------------------------------------------------------------------------------- 17-23 January 2001 At ~1700 on 19 December 2000, a Suwanose-jima inhabitant reported "smoke" rising NE of the summit crater. During observations from a helicopter, ash-laden smoke and high-temperature gas emissions were seen emanating from new craters. The Sakura-jima Volcano Research Center observed an increase in volcanic earthquakes deeper than 1 km below the summit in comparison to Fall 1999. They also noted an increase in volcanic earthquakes and tremor shallower than 1 km in comparison to early 2000. Researchers will continue to closely monitor the volcano. Sources: New York Times, Washington Post Service -------------------------------------------------------------------------------- 9-15 May 2001 Beginning on the morning of 9 May volcanic activity increased at Suwanose-jima when a tremor event commenced. The tremor increased at 1100 and became more violent at 2100. Around noon on 11 May an eruption produced an ash cloud that rose 1-1.5 km above the crater. The Suwanose-jima Branch of Toshima village, ~4 km NNW of the active On-take (Otake) crater, reported that abundant ash fall was observed in the village on 11 May. Vigorous eruptions on the evening of 12 May and the morning of 13 May deposited up to 3 cm of ash in the village. At 0900 on 14 May the eruption seemed to have stopped. The Sakurajima Volcano Observatory reported that plumes associated with volcanic tremor events have been observed at Suwanose-jima since the new crater was formed during the December 2000 eruption. Sources. Volcano Research Center-Earthquake Research Institute (University of Tokyo), Tokyo VAAC -------------------------------------------------------------------------------- 25-31 July 2001 Volcanic tremor was detected near Suwanose-jima's On-take (Otake) crater beginning on 25 July at 2200 until at least 26 July. JMA reported that an eruption on 26 July at 1430 produced a volcanic plume that rose to 1.3 km above the crater and drifted to the S. That day seismometers ~2 km SW of the crater recorded explosions at 0501, 0558, 0935, and 1055. According to the Suwanose-jima Branch of the Toshima Village Office, ash fell the morning of 26 July. Source. Volcano Research Center-Earthquake Research Institute (University of Tokyo) -------------------------------------------------------------------------------- 17-23 October 2001 On 11 October at 1400 an eruption began at Suwanose-jima. Volcanic tremor associated with the eruption was detected during 11 October through at least 15 October. Up to eleven explosions were counted. Acoustic microphones recorded four shock waves associated with large explosions. Sources: Volcano Research Center- Earthquake Research Institute (University of Tokyo), Japanese Meteorological Agency -------------------------------------------------------------------------------- 12-18 June 2002 Based on information from aircraft reports and JMA, the Tokyo VAAC stated that volcanic ash from Suwanose-jima was reported on 18 June at 1058 at a height of ~6 km drifting E. Ash was not visible on satellite imagery. Source: Tokyo VAAC -------------------------------------------------------------------------------- 14-20 August 2002 Small explosive eruptions occurred at Suwanose-jima on 19 August. JMA reported that on the 19th two periods of continuous acoustic signals were recorded for 20-30 minutes each beginning around 0000 and 0630. The signals were the largest recorded thus far this year. Explosions and rumbling were heard from Toshima village, and an ash plume drifted to the SW. Volcanic tremor with continuous large acoustic signals was also recorded later in the day during 0940-0950 and 1410-1500. Small tremor events also occurred, and ash rose above the summit to an unknown height and drifted SE. Sources: JMA-Fukuoka Center via the Volcano Research Center, Kyodo News, Associated Press -------------------------------------------------------------------------------- 21-27 August 2002 Eruptive activity began to decline at Suwanose-jima in comparison to the previous week. Periods of volcanic tremor occurred on the 19th and 20th. According to the Suwanose-jima office of Toshima Village, rumbling sounds were not as strong as those of the previous week, but were sometimes accompanied by the sounds of large explosions on the 20th. Small amounts of ash fell in inhabited areas about 4 km SSW of the summit on the 20th and 21st. On the afternoon of the 20th ash also fell in Naze city on Amami-Oshima Island, about 140 km S of Suwanose-jima. Aerial inspections conducted during the report period by the staff of Kagoshima Meteorological Observatory revealed that an ash-rich cloud rose 1.5 km above the crater and drifted S. Source: JMA-Fukuoka Center via the Volcano Research Center -------------------------------------------------------------------------------- 11-17 September 2002 Activity at Suwanose-jima was relatively low from 26 August until 12 September. On the 12th explosive eruptions began to occur frequently. According to the Suwanose-jima office of Toshima village, rumbling was intermittently heard about 4 km SSW of the summit and small amounts of ash fell. Explosions continued to occur until at least 13 September. Source: JMA-Fukuoka Center via the Volcano Research Center -------------------------------------------------------------------------------- 10-16 December 2003 Based on information from JMA, the Tokyo VAAC reported that an explosion at Suwanose-jima on 15 December at 1946 produced a plume to an unknown height. Source: Tokyo VAAC -------------------------------------------------------------------------------- 17-23 December 2003 Based on information from the Japanese Meteorological Agency, the Tokyo VAAC reported that an explosion at Suwanose-jima on 21 December at 1828 produced a plume to an unknown height. Source: Tokyo VAAC -------------------------------------------------------------------------------- 24-30 December 2003 Based on information from JMA, the Tokyo VAAC reported that several small ash emissions from Suwanose-jima on 27 and 28 December rose to unknown heights. Ash from an eruption on 28 December at 0820 reached a height of ~1.5 km a.s.l. and drifted E. Source: Tokyo VAAC -------------------------------------------------------------------------------- 31 December 2003- 6 January 2004 Based on information from JMA, the Tokyo VAAC reported that on 2 and 4 January small explosions occurred at Suwanose-jima producing ash plumes to unknown heights. Source: Tokyo VAAC -------------------------------------------------------------------------------- 21-27 January 2004 Based on information from the Japanese Meteorological Agency, the Tokyo VAAC reported that explosions at Suwanose-jima on 21 and 22 January produced ash plumes to unknown heights. Source: Tokyo VAAC -------------------------------------------------------------------------------- 28 April- 4 May 2004 According to the Tokyo VAAC, ash emitted from Suwanose-jima was reported on 28 April at a height of ~3 km a.s.l. extending SE. No ash was visible on satellite imagery. JMA reported that an explosion occurred on 1 May at 0906, but it was not known if an ash cloud was produced. Source: Tokyo VAAC -------------------------------------------------------------------------------- 2-8 June 2004 On 7 June Suwanose-jima erupted, producing a plume to ~2 km a.s.l. that extended E. Eruptions continued through 8 June with at least one explosion producing a gas-and-ash plume to ~2 km a.s.l. that also drifted E. Source: Tokyo VAAC -------------------------------------------------------------------------------- 9-15 June 2004 An eruption at Suwanose-jima on 9 June at 1003 produced an ash plume visible on satellite imagery at a height of ~1.8 km a.s.l., extending E. Another explosion at 1300 that day produced an ash plume that reached an unknown height. Source: Tokyo VAAC -------------------------------------------------------------------------------- 30 June- 6 July 2004 Based on information from JMA, the Tokyo VAAC reported that several explosions occurred at Suwanose-jima during 30 June to 5 July. The highest rising plume reached ~1.9 km a.s.l. Source: Tokyo VAAC