Mahawu

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 1.358°N
  • 124.858°E

  • 1324 m
    4343 ft

  • 266110
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Bulletin Report: August 1994 (BGVN 19:08)


Mudpots, small geysers, and vigorous, noisy fumaroles

Part of the EVS report follows. "During our observations at 1100 on 9 July intense and noisy gas emissions (like a jet engine) occurred near the low NW part of the inner wall of the crater. These gas emissions generated a gray-white plume. This area of the crater was covered by many yellow sulfur deposits. A strong smell of hydrogen sulfide was also noted. An important solfatara zone surrounded the NW, N, NE, and E sides of the green, ~40,000 m3, acidic crater lake. Two small geysers, the one in the N and the other in the NW, were very active (2-3 m height). Several boiling basins and mud pots were active around the lake. It was not possible to get down into the crater without rock climbing equipment, because the crater walls were very steep." EVS observers also proposed that a low part of the S wall had collapsed.

Information Contacts: H. Gaudru, C. Pittet, M. Auber, C. Bopp, and O. Saudan, EVS, Switzerland.

The Global Volcanism Program has no Weekly Reports available for Mahawu.

Index of Bulletin 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.

04/1987 (SEAN 12:04) Tectonic earthquakes, plume, elevated lake temperature

06/1987 (SEAN 12:06) Lake volume and temperature increase, seismicity rises

07/1987 (SEAN 12:07) White plume present, 1977 activity reviewed

08/1987 (SEAN 12:08) 1977 lake data corrected

11/1991 (BGVN 16:11) Increased thermal activity

08/1994 (BGVN 19:08) Mudpots, small geysers, and vigorous, noisy fumaroles




Bulletin Reports

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


04/1987 (SEAN 12:04) Tectonic earthquakes, plume, elevated lake temperature

Beginning on 17 April, a white plume was observed ~100 m above Mahawu crater. The plume persisted into early May. Between 1 and 22 April, tectonic earthquakes occurred at a rate of 1/day, with no shallow volcanic earthquakes. During the last week of April, tectonic earthquakes occurred at a rate of ~9/day and shallow volcanic events at ~5/day.

Mahawu contains a crater lake with a volume of ~40,000 m3 of greenish-yellow water. On 21 April the temperature of the lake water was 45°C, compared to a normal 20°C measured in September 1986. A strong odor of H2S was also noted by the VSI observer during his 21 April visit. VSI recommended that a circular area extending ~3.5 km from the crater be temporarily closed to public access. In January 1978, the temperature of the lake water reached 70°C without an eruption [but see 12:7 & 8].

Information Contacts: T. Casadevall, USGS & VSI.

06/1987 (SEAN 12:06) Lake volume and temperature increase, seismicity rises

A 100-m white plume was first seen emerging from the summit crater on 17 April (12:04). A similar whitish plume was continuously present above the summit in May and June. Both tectonic and volcanic earthquakes had increased at the end of April and continued to be recorded in May and June. By 30 June, the crater lake volume had increased to 45,000 m3 and water temperature had increased to 48°C.

Information Contacts: VSI.

07/1987 (SEAN 12:07) White plume present, 1977 activity reviewed

White fume was continuously present above the crater rim to 100 m heights. Fewer than five volcanic earthquakes were recorded/day. Some tectonic earthquakes were also recorded.

In 12:4 we reported that the temperature of the crater lake rose to 70°C in January 1978 without an eruption. However, Nairn and Bachri (1978) report that on 16 November 1977, the crater lake, 800 m in diameter and 10 m deep, was gray colored and turbid with strong central upwelling and had a temperature of 85.5°C [but see 12:8]. Moderately loud explosions were heard every 5-10 minutes followed by 2-3-m-high spearhead projections of water and lake-floor debris. Along the NE shore fine gray mud was deposited to 20 m above the lake. A strong H2S odor was present.

Reference. Nairn, I. and Bachri, S., 1978, Several annotations about Mahawu's crater activities in recent times: Berita Direktorat Geologi, v. 10, no. 5, p. 55.

Information Contacts: VSI.

08/1987 (SEAN 12:08) 1977 lake data corrected

During the November 1977 visit by Nairn and Bachri, the crater lake was 80 m in diameter and its temperature was 65.5°C (correcting the values reported in 12:07). Lake depth was estimated at 10 m by a guide, based on his earlier observation of the crater floor at a time when the lake was dry. The explosions from the lake were quite small.

Information Contacts: I. Nairn, NZGS Rotorua, New Zealand.

11/1991 (BGVN 16:11) Increased thermal activity

Mahawu began to show signs of renewed activity in mid-Nov, about a month after the eruption of Lokon-Empung, 7 km WNW. Temperatures increased at the solfataras and fumaroles in and around the crater lake, and a vapor column rose 50-200 m above the crater. Although no magmatic eruption was observed, mud boiling from the base of the crater lake generated tremor with 1-2 mm amplitude. No volcanic tremor was detected. As of mid-Dec, degassing episodes were decreasing in number and intensity.

Information Contacts: VSI.

08/1994 (BGVN 19:08) Mudpots, small geysers, and vigorous, noisy fumaroles

Part of the EVS report follows. "During our observations at 1100 on 9 July intense and noisy gas emissions (like a jet engine) occurred near the low NW part of the inner wall of the crater. These gas emissions generated a gray-white plume. This area of the crater was covered by many yellow sulfur deposits. A strong smell of hydrogen sulfide was also noted. An important solfatara zone surrounded the NW, N, NE, and E sides of the green, ~40,000 m3, acidic crater lake. Two small geysers, the one in the N and the other in the NW, were very active (2-3 m height). Several boiling basins and mud pots were active around the lake. It was not possible to get down into the crater without rock climbing equipment, because the crater walls were very steep." EVS observers also proposed that a low part of the S wall had collapsed.

Information Contacts: H. Gaudru, C. Pittet, M. Auber, C. Bopp, and O. Saudan, EVS, Switzerland.

The elongated Mahawu volcano immediately east of Lokon-Empung volcano is the northernmost of a series of young volcanoes along a SSW-NNE line near the margin of the Quaternary Tondano caldera. Mahawu is capped by a 180-m-wide, 140-m-deep crater that sometimes contains a small crater lake, and has two pyroclastic cones on its northern flank. Less active than its neighbor, Lokon-Empung, Mahawu's historical activity has been restricted to occasional small explosive eruptions recorded since 1789. In 1994 fumaroles, mudpots, and small geysers were observed along the shores of a greenish-colored crater lake.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1977 Nov 16 Unknown Confirmed 0 Historical Observations
1958 Jul 12 1958 Jul 29 Confirmed 2 Historical Observations
1952 Unknown Confirmed 2 Historical Observations
1904 Oct 4 (in or before) Unknown Confirmed 2 Historical Observations
1846 Unknown Confirmed 2 Historical Observations
1789 Dec 31 ± 365 days Unknown Confirmed 2 Historical Observations
1788 (in or before) Unknown Confirmed   Historical Observations

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.


Synonyms

Mahawoe | Roemengan | Rumengan

Cones

Feature Name Feature Type Elevation Latitude Longitude
Masarang Cone 1236 m
Tombuluan Cone 455 m

Craters

Feature Name Feature Type Elevation Latitude Longitude
Niawuan Crater
Wagio Crater
Mahawu volcano, located immediately to the east of Lokon-Empung volcano, contains a 450-m-wide, 140-m-deep summit crater. Active fumaroles are seen in this 1991 photo of the north end of the crater, which sometimes contains a crater lake. Small-to-moderate explosive eruptions have been recorded at 1331-m-high Mahawu volcano since the 18th century.

Photo by Ruska Hadian, 1991 (Volcanological Survey of Indonesia).

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.

Kusumadinata K, 1979. Data Dasar Gunungapi Indonesia. Bandung: Volc Surv Indonesia, 820 p.

Matahelumual J, 1986b. G Lokon-Empung. Bull Volc Surv Indonesia, 114: 1-52 (in Indonesian).

Morrice M G, Jezek P A, Gill J B, Whitford D J, Monoarfa M, 1983. An introduction to the Sangihe arc: volcanism accompanying arc-arc collision in the Molucca Sea, Indonesia. J Volc Geotherm Res, 19: 135-165.

Neumann van Padang M, 1951. Indonesia. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 1: 1-271.

Volcano Types

Stratovolcano
Pyroclastic cone(s)

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Major
Andesite / Basaltic Andesite
Dacite
Basalt / Picro-Basalt

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
18,618
111,852
878,193
1,503,109

Affiliated Databases

Large Eruptions of Mahawu 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.