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Additional Reports

Reports are sometimes published that are not related to a Holocene volcano. These might include observations of a Pleistocene volcano, earthquake swarms, or floating pumice. Reports are also sometimes published in which the source of the activity is unknown or the report is determined to be false.

Possible 1988 Eruption Plume

northern Kuril Islands

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11/1988 (SEAN 13:11) Possible eruption cloud seen by airplane pilot

Contents of Monthly Reports

All information contained in these reports is preliminary and subject to change.

11/1988 (SEAN 13:11) Possible eruption cloud seen by airplane pilot

While flying 170 km E of the Kuril Islands on 27 October at 1907, the pilot of Japan Airlines flight 81 (Anchorage, Alaska to Tokyo) observed a spherical blue-white cloud slightly above the WNW horizon. The cloud looked to the pilot like a volcanic plume and was rapidly developing a mushroom head. Visibility was unlimited in moonlight. Airborne radar is generally not able to detect volcanic clouds, and there was no echo from this cloud on the aircraft's radar scope. Winds were blowing from the cloud toward the aircraft at ~55-75 km/hour, and the pilot diverted S to avoid it.

The air route nearest the Kuril Islands (R220) and the neighboring westbound route (R580) were closed to air traffic by Japanese authorities. A third parallel route (A590), normally eastbound, was opened in both directions (at different altitudes) to accommodate aircraft from the two closed routes. Although a reconaissance flight the next day detected what its pilot described as a possible ash cloud below 8.5 km altitude, the closed routes were reopened for their normal use by higher altitude traffic.

At the time of the sighting, the aircraft was at about 48.65 N, 157.45 E, 11 km altitude. The cloud was ~45 to the right of the flight path, prescribed at 238 for that section of the air route (R220). The resultant bearing of 283 to the cloud crosses the northern Kurils near Harimkotan Island, ~170 km from the aircraft. Several recently active volcanoes, including Harimkotan, Chrinokotan, Ekarma, Sinarka, and the Tao Rusyr caldera, are within a few degrees of the 283 bearing from the point of the sighting. However, the IV had no reports of any eruptions in the area at that time, and an October survey of the southern Kurils found only mild fumarolic activity. A strong cold front was passing through the area around the time of the 27 October observation, and might have produced volcanic-like cloud formations.

Information Contacts: N. Krull, FAA; E. Miller, ALPA; Y. Tsukamoto, ALPA of Japan; W. Gould, NOAA/NESDIS; S. Fedotov and B. Ivanov, IV.