Agua de Pau

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  • 37.77°N
  • 25.47°W

  • 947 m
    3106 ft

  • 382090
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Most Recent Bulletin Report: March 1989 (SEAN 14:03)


Seismicity since May 1988 summarized

[Agua de Pau information only; extracted from a summary of significant seismic activity in the E Azores (figure 1) since May 1988.]

Figure 1. Sketch map showing islands in the eastern Azores. Approximate epicenters of the 3-5 October 1988 swarm at the submarine volcano Don Joao de Castro Bank (4) and the 21 November 1988 and 21 January 1989 earthquakes in the Hirondelle Basin (6 and 7) are shown. Courtesy of R. Moore.

"A swarm of microearthquakes, accompanied by weak harmonic tremor, occurred beneath the NE flank of Agua de Pau Volcano on Sao Miguel (figure 2, zone 1) 23-24 May 1988. Seismometers recorded 383 earthquakes; the largest had intensities of MM IV-V in villages along the N coast. A similar but smaller swarm occurred in the same area in 1983 and was recorded by USGS seismographs. Numerous, small, normal faults (including some that show scissor-type movement) displace basaltic, tristanitic, and trachytic vent deposits and flows in this area. However, the area has had no eruptions for about 3,000 years and is the least active of the five volcanic zones on Sao Miguel that have erupted during Holocene time.

Figure 2. Approximate epicenters for earthquakes on and near the island of Sao Miguel, May-October, 1988. Courtesy of R. Moore.

"A small swarm of microearthquakes occurred 24-26 June [1988] on the S flank of Agua de Pau Volcano (zone 2). Sixty-four earthquakes were recorded; the largest had intensities of MM III-IV in nearby villages. No tremor accompanied this episode.

"A small swarm of microearthquakes occurred 6 July [1988] near the S coast of Sao Miguel (zone 3). Fifty-one earthquakes were recorded; the largest was felt and had an intensity of MM III-IV. No tremor accompanied this episode.

Information Contacts: A. Rodrigues da Silva, Consorcio Geotermico de S. Miguel; R. Moore, USGS; National Institute of Meteorology and Geophysics, Portugal.

The Global Volcanism Program has no Weekly Reports available for Agua de Pau.

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.

03/1989 (SEAN 14:03) Seismicity since May 1988 summarized




Bulletin Reports

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


03/1989 (SEAN 14:03) Seismicity since May 1988 summarized

[Agua de Pau information only; extracted from a summary of significant seismic activity in the E Azores (figure 1) since May 1988.]

Figure 1. Sketch map showing islands in the eastern Azores. Approximate epicenters of the 3-5 October 1988 swarm at the submarine volcano Don Joao de Castro Bank (4) and the 21 November 1988 and 21 January 1989 earthquakes in the Hirondelle Basin (6 and 7) are shown. Courtesy of R. Moore.

"A swarm of microearthquakes, accompanied by weak harmonic tremor, occurred beneath the NE flank of Agua de Pau Volcano on Sao Miguel (figure 2, zone 1) 23-24 May 1988. Seismometers recorded 383 earthquakes; the largest had intensities of MM IV-V in villages along the N coast. A similar but smaller swarm occurred in the same area in 1983 and was recorded by USGS seismographs. Numerous, small, normal faults (including some that show scissor-type movement) displace basaltic, tristanitic, and trachytic vent deposits and flows in this area. However, the area has had no eruptions for about 3,000 years and is the least active of the five volcanic zones on Sao Miguel that have erupted during Holocene time.

Figure 2. Approximate epicenters for earthquakes on and near the island of Sao Miguel, May-October, 1988. Courtesy of R. Moore.

"A small swarm of microearthquakes occurred 24-26 June [1988] on the S flank of Agua de Pau Volcano (zone 2). Sixty-four earthquakes were recorded; the largest had intensities of MM III-IV in nearby villages. No tremor accompanied this episode.

"A small swarm of microearthquakes occurred 6 July [1988] near the S coast of Sao Miguel (zone 3). Fifty-one earthquakes were recorded; the largest was felt and had an intensity of MM III-IV. No tremor accompanied this episode.

Information Contacts: A. Rodrigues da Silva, Consorcio Geotermico de S. Miguel; R. Moore, USGS; National Institute of Meteorology and Geophysics, Portugal.

Agua de Pau stratovolcano in central Sao Miguel Island contains an outer 4 x 7 km caldera formed about 30,000 to 45,000 years ago and an inner 2.5 x 3 km caldera that was created about 15,000 years ago. The younger caldera is partially filled by the Lagoa do Fogo caldera lake. Several post-caldera lava domes were emplaced on the northern and western flanks of the volcano, but activity in the caldera did not resume until about 5000 years ago. The 3-cu-km Fogo-A plinian pumice-fall deposit, the product of the largest-known Holocene eruption in the Azores, was emplaced at this time. Numerous flank cinder cones mark radial and concentric fissures, some of which have been active during historical time. The latest trachytic explosive eruption took place during 1563. Prominent hot springs are located on the NW flank.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1564 Feb 10 1564 Feb 12 Confirmed 2 Historical Observations Lagoa do Fogo caldera
1563 Jun 28 1563 Jul 26 ± 5 days Confirmed 5 Historical Observations Caldera, NW flank (Cerro Queimado)
0700 ± 150 years Unknown Confirmed   Radiocarbon (uncorrected) WNW flank (Mos)
0160 ± 150 years Unknown Confirmed   Radiocarbon (uncorrected) NW flank (251 m)
1290 BCE (?) Unknown Confirmed 4 Radiocarbon (uncorrected) Lagoa do Fogo caldera
1850 BCE ± 500 years Unknown Confirmed 3 Radiocarbon (uncorrected) East flank (Lagoa do Congro)
2210 BCE ± 150 years Unknown Confirmed   Radiocarbon (uncorrected) East flank (East Congo maar)
2990 BCE (?) Unknown Confirmed 5 Radiocarbon (uncorrected) Lagoa do Fogo caldera and north flank
4550 BCE ± 100 years Unknown Confirmed   Radiocarbon (uncorrected) SW flank (449 m)
6750 BCE ± 200 years Unknown Confirmed   Radiocarbon (uncorrected) West flank (Pico Joao Fernandes)

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

Vulcao de Lagoa do Fogo | Fogo

Cones

Feature Name Feature Type Elevation Latitude Longitude
Escuro, Monte Cone 889 m 35° 47' 0" N 25° 26' 0" W
Joao Fernandes, Pico Cone 386 m 35° 46' 0" N 25° 33' 0" W
Mariana, Pico da Cone 445 m 35° 45' 0" N 25° 31' 0" W
Mos Cone 358 m 37° 46' 0" N 25° 33' 0" W
Vermelho, Pico Cone 269 m 35° 48' 0" N 25° 30' 0" W

Craters

Feature Name Feature Type Elevation Latitude Longitude
Congro, Lagoa do Maar 569 m 35° 45' 0" N 25° 25' 0" W
Fogo, Lagoa do Pleistocene caldera 948 m 35° 46' 0" N 25° 28' 0" W
San Bras, Lagoa de Maar 711 m 35° 48' 0" N 25° 25' 0" W

Domes

Feature Name Feature Type Elevation Latitude Longitude
Altinetes, Pico Dome 226 m 37° 48' 0" N 25° 33' 0" W
Barnabe, Pico Dome 213 m 37° 48' 0" N 25° 33' 0" W
Cerrado Novo Dome 532 m 35° 48' 0" N 25° 27' 0" W
Cintrao Dome 166 m 35° 50' 0" N 25° 29' 0" W
Queimado, Cerro Dome 347 m 37° 47' 0" N 25° 33' 0" W

Thermal

Feature Name Feature Type Elevation Latitude Longitude
Velha, Caldeira Thermal
The inner Agua de Pau caldera, seen here from the western caldera rim, is now partially filled by Lagoa do Fogo caldera lake. The caldera was the source of a major explosive eruption about 5000 years ago. This eruption produced tephra layer Fogo A, which marked the renewal of major explosive activity within the 15,000-year-old inner Agua de Pau caldera. The eruption produced pyroclastic flows and thick mudflows that reached the northern and southern coasts of Sao Miguel Island.

Photo by Rick Wunderman, 1997 (Smithsonian Institution).
Lagoa do Fogo ("Fire Lake") appears to occupy a line of craters possibly dating from a major eruption during 1563. A plinian eruption from the central caldera began on June 28, 1563, depositing trachytic pumice eastward over the island. On July 2, a NW-flank effusive eruption began, which lasted until the end of July and produced a lava flow that reached the northern coast at Ribeira Grande.

Photo by Rick Wunderman, 1997 (Smithsonian Institution).
Lagoa do Fogo lake, seen here from the west, partially fills the younger of two Pleistocene calderas on Agua de Pau stratovolcano in central Sao Miguel Island. Several post-caldera lava domes were emplaced on the northern and western flanks of the volcano, but activity inside the caldera did not resume until the eruption of the 5000-year-old Fogo-A plinian pumice-fall deposit, the product of the largest-known Holocene eruption in the Azores. Numerous cinder cones have erupted on the flanks of Agua de Pau during historical time.

Photo by Rick Wunderman, 1977 (Smithsonian Institution).
The forested ridge in the center of the photo is part of the northern rim of the 2.5 x 3 km inner Agua de Pau caldera. The Serra de Agua de Pau hills in the background mark the northern rim of an outer 4 x 7 km caldera of Pleistocene age, which formed approximately 33,000 years ago. Lagoa de Fogo caldera lake (lower right) partially fills the inner caldera.

Photo by Rick Wunderman, 1997 (Smithsonian Institution).
A public fountain at Ribeira Grande on the northern coast of San Miguel Island was buried by a lava flow that was erupted from Agua de Pau volcano in 1563. The fountain had been constructed sometime during the half century prior to the 1563 eruption. The lava flow, which originated on July 2 from a vent of the NW flank of Cerro Queimado, remained active until the end of the month. It was preceded by a major plinian eruption from the central caldera that began on June 28 and deposited trachytic pumice eastward over the island.

Photo by Rick Wunderman, 1997 (Smithsonian Institution).

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.

Booth B, Croasdale R, Walker G P L, 1978. A quantitative study of five thousand years of volcanism on Sao Miguel, Azores. Phil Trans Roy Soc London, Ser A, 288: 271-319.

Capaccioni B, Forjaz V H, Martini M, 1994. Pyroclastic flow hazard at Agua de Pau volcano (Sao Miguel Island, Azores archipelago) inferred from the Fogo A eruptive unit. Acta Vulc, 5: 41-48.

Martins J A, 1982. Excursion guide for field trip V1, Island of Sao Miguel. Proc Internatl Symp Activity Oceanic Volc, Archipelago Univ Azores, 3: 315-328.

Moore R B, 1983b. Preliminary geologic map of Furnas volcano, Sao Miguel, Azores (1:15,000). U S Geol Surv Open-File Rpt, 83-395.

Moore R B, 1986. Preliminary geologic map of Agua de Pau volcano, Sao Miguel, Azores. U S Geol Surv Open-File Rpt, 86-192.

Moore R B, 1990. Volcanic geology and eruption frequency, Sao Miguel, Azores. Bull Volc, 52: 602-614.

Moore R B, 1991. Geologic map of Sao Miguel, Azores. U S Geol Surv Map, I-2007.

Neumann van Padang M, Richards A F, Machado F, Bravo T, Baker P E, Le Maitre R W, 1967. Atlantic Ocean. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 21: 1-128.

Zbyszewski G, Moitinho de Almeida F, Veiga Ferreira O da, Torre de Assuncao C, 1958. Geologic map of Sao Miguel (Azores). Servicos Geologicos Portugal, two 1:50,000 scale maps with 22 and 37 p texts (in Portuguese).

Volcano Types

Stratovolcano
Caldera(s)
Lava dome(s)
Pyroclastic cone(s)

Tectonic Setting

Rift zone
Oceanic crust (< 15 km)

Rock Types

Major
Trachyte / Trachyandesite
Trachybasalt / Tephrite Basanite
Basalt / Picro-Basalt
Trachyandesite / Basaltic trachy-andesite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
406
17,272
113,131
119,653

Affiliated Databases

Large Eruptions of Agua de Pau 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.