(09/12/02)
According to the Volcano Observation Report No. 14 on Suwanosejima
volcano issued by JMA at the noon, 13 September 2002, the eruption
activity at the summit (Otake) is high in level. Though the activity
of the volcano had been relatively quiet since 26 August, it became
into a high level in the 12 September morning such that explosive
eruptions frequently occurred. According to the Suwanosejima office
of Toshima village, rumbling had been heard intermittently at the
place about 4 km SSW of the summit and small ash falling was observed
on 12 September. Explosions occurred at 0816, 1246, 1746 and 1754 on
12 September, and 0853, 1016 and 1027 on 13 September.
Information contact: JMA-Fukuoka center, N. Uchida; n-uchida@met.kishou.go.jp
(08/21/02)
JMA issued Volcano Observation Report nos. 9 and 10 on Suwanose-jima
on August 20 and 21 respectively: eruptive activity still continued,
though declined. Volcanic tremor events occurred at 1810-1815 and
1920-1930, on August 19, 0115-0120, August 20, and 0625-0655, August
20. According to the Suwanose-jima office of the Toshima Village,
rumbling became smaller, being sometimes accompanied by large
explosion sounds on August 20. Faint ash falling was observed in the
resident area about 4 km SSW of the summit on August 20 and 21. Ash
falling was recorded in the Naze city, Amami-oshima island, about 140
km S of Suwanose-jima on the August 20 afternoon.
Staffs of the Kagoshima Meteorological Observatory inspected the activity from the air, being supported by the Maritime Self-Defense Force. It is likely that he crater of the December 2000 eruption was smoking. The cloud abundant ash was drifting to S in the height of 1,500 m above the crater.
Information contact: JMA-Fukuoka center, N. Uchida; n-uchida@met.kishou.go.jp
Eruption clouds on Suwanosejima through live camera images
provided by
Satellite
Image Network Group (SiNG), Faculty of Education, Kagoshima
University,
seen from Nakanoshima (about 25 km NE of Suwanosejima)
(08/20/02)
JMA issued Volcano Advisory No. 1 on Suwanosejima volcano on the Aug.
19 morning. Volcanic tremor events associated with continuous
acoustic signals took place during 20-30 minutes around 00 h and 06h
30m (JST) respectively. The acoustic signals were largest for this
one year. According to the Toshima village, they could have heard the
explosion sounds every 2 to 3 seconds and continuous rumbling. The
summit was covered with cloud. Abundant ash was drifted to SW. The
Volcano Observation Report no. 8, successively issued in the
afternoon, said that volcanic tremors with continuous large acoustic
signals occurred also during 0940-0950, 1410-1500. In addition, small
tremor events had occurred. The summit crater was smoking, but the
height was not known. Volcanic ash was being drifted to SE.
Information contact: JMA-Fukuoka center, N. Uchida; n-uchida@met.kishou.go.jp
Eruption clouds on Suwanosejima through live camera images
provided by
Satellite
Image Network Group (SiNG), Faculty of Education, Kagoshima
University,
seen from Nakanoshima (about 25 km NE of Suwanosejima)
(10/20/01)
JMA issued the Volcano Observation Reports Nos. 8-10 on Suwanosejima during October 11-15. Eruption at Otake crater began around 2 p.m. of Oct. 11, following the latest eruptive activity that ended on July 30. Volcanic tremor event of the eruption that started around noon of October 11 had continued as of the afternoon of October 15. Explosions counted up to eleven times. Acoustic microphone installed in the island recorded four times of shock waves associated with large explosions.
Information contact: N. Uchida of JMA, Fukuoka: n-uchida@met.kishou.go.jp
(7/26/01)
Active eruptions had continued at Otake of Suwanosejima. JMA
issued the Observation Reports #6 and 7 on Suwanosejima Volcano on 26
July. According to them, the height of the volcanic plume drifting
southward was 1300 m above the crater at 14:30. The JMA seismometer
installed about 2 km SW of the crater, recorded explosion at05:01,
05:58, 09:35 and 10:55. Volcanic tremor had continued since around 22
h of 25 July. According to the Suwanosejima Branch of the Toshima
Village Office, ash was falling in the 26 July morning.
Information: JMA_Fukuoka, Naokuni Uchida:
n-uchida@redc-fk.eqvol.kishou.go.jp
(May 14, 2001)
According to the Suwanose-jima Branch of Toshima-Village, whose main office is in a different island, reported that falling of abundant ash was observed around 08:45 on 11 May in the village about 4 km NNW of the active crater (Otake), such that cars could not run without dusting the front windows. The eruptions that occurred during the 12 May evening to the 13 May morning were vigorous, and ash deposition was as thick as 3 cm in the village. At 06:30 on 13 May, still erupting but neither sound nor vibration. It seemed not to be erupted at 09:00 on 14 May, and cleaning of ash deposits from the roads started in the village.
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Infromation contact: JMA; n-uchida@met.kishou.go.jp, and
VRC: nakada@eri.u-tokyo.ac.jp
(May 11, 2001)
According to Sakurajima Volcano Research Center (Sakurajima Volcano Observatory) of Disaster Prevention Research Institute, Kyoto University, eruption plumes had been observed in Suwanosejima volcano, being associated with volcanic tremor events, since the eruption of last December that formed new craters. A tremor event started on the May 9 morning, and the number of events increased since 11 a.m. The events moved into more violent activity associated with acoustic signals around 9 p.m. Such the activity is first since June 1999. Compared with a highly active period before 1995, the amplitude of acoustic signals and the number of occurrence are small. SVRC was calling people's attention to the volcanic activity that may become more explosive.
JMA issued the Volcano Observation Reports #3 and #4 on this volcano on 10 and 11 May, respectively. They include the reports from the Toshima Village officials; the height of gray-colored eruption column was rising about 1,000 to 1,500 m above the crater around the 11 May noon, and ash falling was observed. No felt earthquake reported.
Figure
of Daily numbers of eruptions, tremor events, B and A earthquakes
(in Japanese) (to the bottom): jump to SVRC site. Here, an eruption
is defined as a volcanic earthquake, associated with an acoustic
signal more than 1 Pa.
Figure
of seismic waves: jump to SVRC site. From the top, up-and-down,
south-north, and east-west components. The bottom is an acoustic wave
by a microphone.
(Jan. 8, 2001)
The following news comes from
the
homepage of DPRI, Kyoto University.
A Suwanose-jima's inhabitant reported that a smoke was rising from NE
of the summit crater around 5 p.m. (JST) of 19 December 2000. The
next day, Prof. Kazuhiro Ishihara of Sakurajima Volcano Research
Center (former Sakurajima Volcano Observatory), Kyoto University
inspected the crater area from a helicopter of the Kagoshima
Prefecture. He observed ash-laden smoke and high-temperature gas
emission from new craters formed on the E to NE outer-slope of the
summit crater. Observation by Sakurajima Volcano Research Center
shows the numbers of volcano quakes deeper than 1 km below the summit
had increased a little since the 1999 fall (3 to 10 times a month).
Those of volcanic quakes and tremor that are shallower than 1 km had
also increased since the early 2000 (20-50 times and 50-300 times a
month). Sakurajima Volcano Research Center suggested a relatively
high activity but not so high activity as the latest active period in
1992-1993.GPS indicates 1-cm elongation of distance between
Suwanose-jima and Nakano-shima, a neighbor island.
Diagram
of seismic activity by Sakurajima Volcano Research Center (former
Sakurajima Volcano Observatory): in Japanese, monthly numbers of
explosion, tremor, and A- and B-type earthquakes from the top.
Prof. Masato Iguchi and Dr. Daisuke Miki of Sakurajima Volcano
Research Center inspected the crater area from a helicopter in the
morning of 24 December 2000, and measured temperatures of there. i)
Two new craters (craters 1 and 2) locates NE of the summit crater
(crater 1); 30-50 m away from the rim of crater 1
(crater
2) and 200 m away
(crater
3)
(map of
the crater area). ii) The dimensions of the craters 2 and 3 are
20-30 m and 10 m across, respectively
(whole
view). iii) Temperature of crater 1 (with white smokes) is about
450 oC, crater 2 (with ash-laden plume) about 100 oC, and crater 3
(with small amount of ash and volcanic gas) about 270 oC. These data
indicate the activity had become high, but there is no possibility of
a large-scale eruption approaching. Researchers should keep
monitoring this activity in these craters.
Geological
information of Suwanose-jima by Taketo Shimano
(June 16, 1997)
Ash-falling was observed before noon of 24 March and in the evening
of the following day (JMA and Kagoshima Prefectural Government). The
heights of ash column were reported to be about 500 and 600 m above
the summit. Ash emission was also observed on 16-17 April, the column
reached 500-700 m above. SVO, Kyoto University, reported that the
B-type earthquakes were abundant in March (ca. 50/mo.), while
volcanic tremors were abundant April (ca. 200/mo.).
Information contact: Sakurajima Volcanological Observatory (SVO),
Kyoto University, e-mail: ishihara@svo.dpri.kyoto-u.ac.jp; Japan
Meteorological Agency (JMA)
(February 10, 1997)
According to JMA and Kagoshima Prefectural Government, explosions at
Suwanose-jima Volcano occurred on 26-28 December 1996. The height of
eruption column reached up to 600 m above. Small amount of ashfall
was observed in a village S of the crater. SVO reported tremors and
earthquakes (A- and B-types) in small numbers these months in
comparison with the preceding several months.
Information contact: Sakurajima Volcanological Observatory (SVO),
Kyoto University; Japan Meteorological Agency (JMA)
(October 2, 1996)
According to JMA and the Kagoshima Prefectural Government, ash falls
were confirmed within the island on 1-2 June, 4 June, and 13-14 July.
The eruption column on June 2 reached 2100 m high. The explosion
earthquakes associated with eruptions in the early June were recorded
by the seismological net of SVO (Sakurajima Volcanological
Observatory, Kyoto University).
(June 1, 1996)
The activity at Suwanose-jima Volcano has continues in the same
levels since 1994, with nearly constant occurrence of A-type
earthquakes, according to SVO (Sakurajima Volcanological Observatory,
Kyoto University). JMA and Kagoshima Prefectural Government reported
ash emissions on 23 February and 5-6 March, and one explosion at
10:58 JST of 14 April. The eruption column in March reached 500 m
above the volcano.
(February 1996)
The activity of Suwanose-jima Volcano has been in a high level since
1950, such that one or two events of ash emition occurred every
month, sometimes Strombolian explosions. Sakurajima Volcanological
Observatory (SVO), which is monitoring the acitivity of volcanoes in
SW Islands, reported 9 explosions at this volcano in 1995. According
to JMA and Kagoshima Prefectural Government, small eruptions took
place during 10-13 January 1996, and the eruption columns reached
300-600 m above the volcano; ash fall in the south.
(left photo) Eruption at Mitake, Suwanose-jima, on
Oct. 23, 1989 (taken by T. Kagiyama).
This volcano island, 8 x 5 km with the peak of about 800 m altitude,
consists of basaltic andesite and andesite. The largest historical
eruption occurred in 1813-14; as a result, thick scoria beds covered
the residential area and lava flow descended to the west to southwest
from new 300 m-diameter crater. After this event no resident in this
island for about 70 years, and, now, around 50 people are living
there. Large eruptions also occurred in 1884-85 and lava flow reached
the eastern coast.