Manam is a 10-km-wide island that consists of two active summit craters: the Main summit crater and the South summit crater and is located 13 km off the northern coast of mainland Papua New Guinea. Frequent mild-to-moderate eruptions have been recorded since 1616. The current eruption period began during June 2014 and has more recently consisted of ash plumes and thermal activity (BGVN 48:07). This report covers activity during January through June 2023 primarily using various satellite data.

Weak and intermittent sulfur dioxide plumes were detected using the TROPOMI instrument on the Sentinel-5P satellite, some of which exceeded at least two Dobson Units (DU) and drifted in different directions (figure 96). Few low-power thermal anomalies were recorded by the MIROVA (Middle InfraRed Observation of Volcanic Activity) system; two anomalies were captured during January, one during late March, one during early April, one during late May, and one during early June (figure 97). On clear weather days, thermal activity was captured in infrared satellite images in both the Main and South summit craters (figure 98).

Figure 96. Distinct sulfur dioxide plumes were visible rising above Manam based on data from the TROPOMI instrument on the Sentinel-5P satellite on 23 March 2023 (left) and 15 May 2023 (right). Plumes drifted NE and SE, respectively. Courtesy of the NASA Global Sulfur Dioxide Monitoring Page.

Figure 97. Few thermal low-power thermal anomalies were detected at Manam during January through June 2023, as shown in this MIROVA graph (Log Radiative Power). Two anomalies were captured during January, one during late March, one during early April, one during late May, and one during early June. Courtesy of MIROVA.

Figure 98. Infrared (bands B12, B11, B4) satellite images show a consistent thermal anomaly (bright yellow-orange) in both the Main (the northern crater) and South summit craters on 14 January 2023 (top left), 3 February 2023 (top right), 24 April 2023 (bottom left), and 28 June 2023 (bottom right). The two craters are just under 400 m apart. Gas-and-steam emissions occasionally accompanied the thermal activity. Courtesy of Copernicus Browser.

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: MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).