A brief steam emission began at about 1050 on 7 November. Puffs of steam, ejected every 1-5 minutes, rose an estimated 3 km above the summit. No ash was visible in the steam puffs. The activity ended at about 1330. Iliamna's last reported activity occurred 1952-53. A USGS seismic station 20 km NNE of Iliamna recorded no unusual seismicity.

Geological Summary. Iliamna is a prominent glacier-covered stratovolcano in Lake Clark National Park on the western side of Cook Inlet, about 225 km SW of Anchorage. Its flat-topped summit is flanked on the south, along a 5-km-long ridge, by the North and South Twin Peaks lava dome complexes. The Johnson Glacier dome complex lies on the NE flank. Steep headwalls on the S and E flanks expose an inaccessible cross-section of the volcano. Major glaciers radiate from the summit, and valleys below the summit contain debris avalanche and lahar deposits. Only a few major Holocene explosive eruptions have occurred from the deeply dissected volcano, which lacks a distinct crater. Most of the reported eruptions may represent plumes from vigorous fumaroles E and SE of the summit, which are often mistaken for eruption columns (Miller et al., 1998). Eruptions producing pyroclastic flows have been dated to 1778-1779 and 1876 CE. Elevated seismicity accompanying dike emplacement beneath the volcano was recorded in 1996.

Information Contacts: J. Proffett, Anaconda Co., Anchorage; J. Kienle, Univ. of Alaska; J. Lahr, USGS, Menlo Park, CA.