Uncertain ash plume reported by a pilot on 6 July 2013

Vigorous ash plumes from Izu-Torishima (also Torishima) were noted during mid-August 2002 that reached an approximate altitude of 1.2-1.5 km (BGVN 27:07 and 27:10). The volcano apparently remained quiet until 6 July 2013, when a pilot observed an ash plume drifting about 74 km N of the volcano at an altitude of 2.1 km. However, the Tokyo Volcanic Ash Advisory Center did not detect ash in satellite images. The Japan Meteorological Agency (JMA) has no information about this uncertain activity available online.

According to a news account quoting the JMA, a M 6.7 earthquake occurred near Izu-Torishima around 21 April 2013, but there is no evidence this event triggered any explosion.

Information Contacts: Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/).

Information is preliminary and subject to change. All times are local (unless otherwise noted)

January 1977 (NSEB 02:01) Cite this Report

Possible submarine eruption in October 1975

[A table of possible submarine eruptions based on aerial observations of water discoloration by the Japanese Maritime Safety Agency included an entry for 30.38°N, 140.32°E, in October 1975. This location is ~11 km S of Tori-shima.]

Information Contacts: AFP; U.S. Defense Mapping Agency.

July 2002 (BGVN 27:07) Cite this Report

Ash plumes during August 2002 indicate first activity since 1975

Around 1530 on 11 August 2002, a ship sailing near Tori-shima reported white smoke rising from the summit of the island. The Japanese Coast Guard inspected the island from the air during 1738-1818 and confirmed that the plume was rising 200-300 m from near the summit crater (Iwo-yama).

During an overflight on 12 August from 1145 to 1245 by the Japanese Meteorological Agency (JMA), an ash-laden plume was rising from the SW wall of the Iwo-yama summit crater. White plumes were also observed rising from the S to SE crater wall (figures 1 and 2). A vigorous ash plume rose 200-300 m above the crater every few minutes and drifted W to ~1 km above sea level. The summit area and the middle slope NNW of the summit were covered with ashfall deposits. The sea surface was discolored in an area up to 20 km W of the island. Izu-Tori-shima island is currently uninhabited.

Figure 1. Photo showing the Iwo-yama crater of Tori-shima volcano, taken around 1200 on 12 August 2002. Courtesy JMA.

Figure 2. Southern view of Tori-shima volcano showing ash plume from the summit crater, taken around 1200 on 12 August 2002. Courtesy JMA.

Information Contacts: Tomonori Kannno and Hitoshi Yamasato, Japanese Meteorological Agency (JMA), Volcanological Division, 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.jma.go.jp/).

October 2002 (BGVN 27:10) Cite this Report

Mid-August 2002 plumes, larger crater, and discolored water

Following ship-based reports of activity at Tori-shima on 11 August 2002, scientists from the Japanese Meterological Agency overflew the area the next day when they observed and photographed ash plumes being erupted from the crater (BGVN 27:07). According to the Japan Coast Guard (via JMA), the activity continued as of 1200 on 14 August; the plume reached ~1.2-1.5 km above sea level on 13 August (figure 3), and ~900 m on 14 August. Emissions were observed from three active areas along the western inner-wall of the summit crater. The crater appeared to have widened. By 21 August, the Japan Coast Guard reported that Izu-Tori-shima no longer "smoked" and only weak steaming was seen in the southern portion of the crater. Faintly discolored sea surface was observed around the island.

Figure 3. Izu-Tori-Shima plume on 13 August 2002. Courtesy Air Force Weather Agency.

Information Contacts: Tomonori Kannno and Hitoshi Yamasato, Japanese Meteorological Agency (JMA), Volcanological Division, 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.jma.go.jp/); Volcano Research Center (VRC), Earthquake Research Institute (ERI), University of Tokyo (URL: http://www.eri.u-tokyo.ac.jp/VRC/index_E.html); U.S. Air Force Weather Agency, Offutt AFB, NE 68113-4039, USA.

August 2015 (BGVN 40:08) Cite this Report

Uncertain ash plume reported by a pilot on 6 July 2013

Vigorous ash plumes from Izu-Torishima (also Torishima) were noted during mid-August 2002 that reached an approximate altitude of 1.2-1.5 km (BGVN 27:07 and 27:10). The volcano apparently remained quiet until 6 July 2013, when a pilot observed an ash plume drifting about 74 km N of the volcano at an altitude of 2.1 km. However, the Tokyo Volcanic Ash Advisory Center did not detect ash in satellite images. The Japan Meteorological Agency (JMA) has no information about this uncertain activity available online.

According to a news account quoting the JMA, a M 6.7 earthquake occurred near Izu-Torishima around 21 April 2013, but there is no evidence this event triggered any explosion.

Information Contacts: Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/).