Ash explosions occurred at 1537 on 27 May and 1000 on 28 May, producing columns 250 m high. Continued ash explosions were observed at a rate of 7-16/week, with column heights of 200-400 m. Seismic activity was characterized by explosion earthquakes, averaging 30-50 recorded events/week. Shallow and deep volcanic earthquakes were less frequent (2-8 and 3-9 events/week, respectively). Tectonic earthquakes ranged from 18 to 101 weekly.

Geological Summary. The Lokong-Empung volcanic complex, rising above the plain of Tondano in North Sulawesi, includes four peaks and an active crater. Lokon, the highest peak, has a flat craterless top. The morphologically younger Empung cone 2 km NE has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century. A ridge extending 3 km WNW from Lokon includes the Tatawiran and Tetempangan peaks. All eruptions since 1829 have originated from Tompaluan, a 150 x 250 m crater in the saddle between Lokon and Empung. These eruptions have primarily produced small-to-moderate ash plumes that sometimes damaged croplands and houses, but lava-dome growth and pyroclastic flows have also occurred.

Information Contacts: W. Modjo, VSI.