Dawson Strait Group

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 9.62°S
  • 150.88°E

  • 500 m
    1640 ft

  • 253060
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Dawson Strait Group.

The Global Volcanism Program has no Weekly Reports available for Dawson Strait Group.

Index of Monthly Reports

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

01/1990 (BGVN 15:01) Felt swarm of A- and B-type earthquakes; divers film submarine vents and hear booming and roaring

12/2000 (BGVN 25:12) Occasional seismic swarms 1989-99; no eruptive activity

Contents of Monthly Reports

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

01/1990 (BGVN 15:01) Felt swarm of A- and B-type earthquakes; divers film submarine vents and hear booming and roaring

"A swarm of earthquakes took place in the Esa'Ala area in mid-December 1989. Earthquakes were felt with intensities MM III-V by villagers at Esa'Ala, Dobu Island, and on SE Fergusson Island at Oiau, Deidei, and Numa Numa. The local volcano observatory at Esa'Ala noted felt events on the 10th (26 events), 11th (12), 12th (6), and the 13th (3).

"Reports received at RVO on 11 and 13 December prompted a 5-day on-site inspection and local seismic recording by three RVO officers, 13-18 December. When local recording resumed at Esa'Ala Volcano Observatory (on the 13th), 30 sharp volcano-tectonic earthquakes (A-type with S-P <=1 second) and 57 small low-frequency earthquakes (B-type) were recorded. The rate of occurrence and amplitude of the events decreased progressively (table 1). By the 20th the activity had returned to a background level of a few small A-type and B-type events/day.

Table 1. Number of A- and B-type events recorded at the Esa 'Ala Observatory, 13-17 December 1989.

       Date       A-type  B-type

    13 Dec 1989    30      57
    14 Dec 1989    25      55
    15 Dec 1989    23      27
    16 Dec 1989    12      16
    17 Dec 1989    16       9

"The deployment of two portable seismographs at Numa Numa and Waiope Island, together with the seismograph at the Esa'Ala Volcano Observatory, allowed location of some of the larger earthquakes. Of the five earthquakes located, three occurred in the Dobu passage, another under Dobu Island, and the 5th between Dobu Island and Neumara Island (figure 1). These locations lie [near the outline] of an inferred submerged caldera.

Figure 1. Map of the Dawson Strait Group area, showing volcanic vents, the volcano observatory (with permanent seismograph), sites of two portable seismographs deployed 13-18 December 1989, and the five earthquakes located during that period. Courtesy of RVO.

"The strongest earthquake caused minor landslides from 4-30-m cliffs of pyroclastic deposits along the N and E shores of Dobu Island, and one landslide inland, from a steep gulley on the E flank of Dobu. Ground cracks, 1-4 m inland and 0.5-2 cm wide, reported at Kenaie village on the NE side of Dobu Island were related to the collapse of marine cliffs parallel to their edges.

"Off the N coast of Dobu Island on the afternoon of the 11th, a team of professional divers filmed and photographed very turbulent springs (28°C) and degassing vents through sand holes up to 1 m in diameter, at a depth of 6 m of water. They also reported subcontinuous booming and roaring underwater sounds (at an estimated 30-40 db level).

"The December 1989 earthquake swarm was the first episode of unrest [in this area] since April 1969. At that time (1969), over a period of a few days, 5-7 shocks were felt daily, accompanied by noises. This prompted spontaneous evacuation of villagers on Dobu Island and around Oiau Volcano. Recording at the time was from one station only (ESA). On the basis of the S-P interval (1-1.4 seconds) and reports of earthquake intensities, the swarm was presumed to have originated from the Dobu Passage."

Information Contacts: I. Itikarai and P. de Saint-Ours, RVO.

12/2000 (BGVN 25:12) Occasional seismic swarms 1989-99; no eruptive activity

During August-October 2000 there were no reports of unusual volcanic activity occurring at Esa'ala (also called the Dawson Strait group). RVO had a 1960s-vintage seismic recorder at Esa'ala until 1994. Since then, maintenance and funding problems have meant it has neither functioned nor been replaced. Discussion with Professor Abe following a seismic survey in the area in the second part of 1999 revealed that he had seen continued seismicity at the Esa'ala base station.

The last notable seismic swarm at Esa'ala before the RVO instrument broke down was in November-December 1992. Another prior swarm of earthquakes took place in mid-December 1989 (BGVN 15:01). RVO maintains a part-time observer at Esa'ala who keeps track of felt earthquakes. He typically reports that no felt earthquakes have occurred.

General References. Davies, H.L., 1973, Fergusson Island, Papua New Guinea-1:250,000 Geological Series: Bur. Miner. Resour. Aust. explan. Notes, SC/56-5.

Smith, I.E.M., 1976, Peralkaline rhyolites from the D'Entrecasteaux Islands, Papua New Guinea, in Johnson, R.W., ed., Volcanism in Australasia: Elsevier, Amsterdam, p. 275-285.

Smith, I.E.M., 1981, Young volcanoes in eastern Papua in Johnson, R.W., ed., Cooke-Ravian Volume of Volcanological Papers: Geological Survey of Papua New Guinea Memoir 10, p. 257-265.

Information Contacts: Ima Itikarai, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea (Email: rvo@global.net.pg).

The Dawson Straits, located between eastern Fergusson and western Normanby Islands in the D'Entrecasteaux island group, contains a volcanic field with several volcanic centers that define a possible partly submerged caldera. There have been no historical eruptions from this center, but morphology suggests an extremely young age for some lava flows, and the area displays vigorous thermal activity. The most prominent volcanic centers are Mounts Lamonai and Oiau, located about 10 km apart on the SW tip of Fergusson Island. The 500-m-high summit of Lamonai is capped by a steep-walled crater, and rhyolitic lava flows are exposed on the NE side of the cone. Dominantly volcaniclastic Oiau cone has also produced obsidian lava flows. Dobu Island to the south is formed of coalescing volcanic centers and likewise has produced youthful rhyolitic obsidian flows.

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1350 (?) Unknown Confirmed   Hydration Rind Oiau

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Esa 'Ala | Numanuma | Lamonai-Oiau Group

Feature Name Feature Type Elevation Latitude Longitude
Stratovolcano 284 m 9° 49' 16" S 150° 52' 19" E
Stratovolcano 500 m 9° 37' 0" S 150° 53' 0" E
Oiau, Mount
Stratovolcano 302 m 9° 41' 0" S 150° 52' 0" E
Sanaroa Island Cone 9° 36' 0" S 151° 0' 0" E

Feature Name Feature Type Elevation Latitude Longitude
Atunapara Thermal 9° 37' 0" S 150° 52' 0" E
Bagagaure Thermal 9° 39' 0" S 150° 53' 0" E
Bwasi-Iai-Iai Thermal 9° 39' 0" S 150° 53' 0" E
Thermal 9° 39' 40" S 150° 51' 47" E
Gomwa Bay-Salamo Area Thermal 9° 42' 0" S 150° 48' 0" E
Siosiorena Thermal 9° 39' 0" S 150° 53' 0" E
The Dawson Straits, located between eastern Fergusson Island (upper left) and western Normanby Island (lower left) in the D'Entrecasteaux island group, contains a volcanic field with several young volcanic centers that produced rhyolitic obsidian flows. Mount Oiau lies along the narrow peninsula (left-center) forming the southernmost point on Fergusson Island. A large crater is visible on Dobu Island in this NASA Landsat image, south of Oiau and east of Normanby Island. Young volcanic rocks are also found on Sanaroa Island (upper right).

NASA Landsat7 image (worldwind.arc.nasa.gov)

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Cooke R J S, Johnson R W, 1978. Volcanoes and volcanology in Papua New Guinea. Geol Surv Papua New Guinea Rpt, 78/2: 1-46.

Fisher N H, 1957. Melanesia. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 5: 1-105.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Newhall C G, Dzurisin D, 1988. Historical unrest at large calderas of the world. U S Geol Surv Bull, 1855: 1108 p, 2 vol.

Smith I E M, 1976. Peralkaline rhyolites from the d'Entrecasteaux Islands, Papua New Guinea. In: Johnson R W (ed) {Volcanism in Australasia}, Amsterdam: Elsevier, p 275-285.

Smith I E M, 1981. Young volcanoes in eastern Papua. Geol Surv Papua New Guinea Mem, 10: 257-265.

Smithsonian Institution-GVN, 1990-. [Monthly event reports]. Bull Global Volc Network, v 15-33.

Volcano Types

Volcanic field

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Trachyte / Trachyandesite
Trachyandesite / Basaltic trachy-andesite


Within 5 km
Within 10 km
Within 30 km
Within 100 km

Affiliated Databases

Large Eruptions of Dawson Strait Group Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.