"After reactivation of Main crater on 10 April, moderate volumes of dark grey-brown ash-laden emissions from this crater continued to be observed on most days in May. This activity was stronger in the first half of the month when roaring, rumbling, and explosion sounds accompanied the ash emissions. Fine ashfalls, probably from Main crater, took place on the E coast on 11, 13, 14, and 16-17 May. No crater glows or incandescent tephra ejections from Main crater were seen in May.

"Southern crater showed a low level of activity throughout May, releasing small to moderate volumes of grey-brown ash-laden emissions on most days. Blue vapour emissions were common. Weak crater glow was observed occasionally from the 14th.

"Seismicity was at a low (normal) level throughout May. Tilt measurements were steady in the first half of the month, but a slight inflation (about 1 µrad accumulated during the second half."

Geological Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical basaltic-andesitic stratovolcano to its lower flanks. These valleys channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most observed eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.

Information Contacts: C. McKee, RVO.