Qualibou

Photo of this volcano
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 13.83°N
  • 61.05°W

  • 777 m
    2549 ft

  • 360140
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Bulletin Report: May 1990 (BGVN 15:05) Citation IconCite this Report


Apparent volcanic earthquakes clustered about 6 km ESE of Qualibou Caldera

"Since 17 May 1990, seismic stations in St. Lucia have been registering local earthquakes that appear to be of volcanic origin (both A- and B-type events were observed). About 172 events were detected by seismic station SLB (figure 1) from 17 May to 10 June, with peak activity occurring on 19 and 20 May (figure 2).

Figure (see Caption) Figure 1. Map of St. Lucia, showing earthquake epicenters 17 May-10 June 1990 and locations of seismograph stations. The broken line represents the limits of Qualibou caldera. Courtesy of the Seismic Research Unit, UWI.
Figure (see Caption) Figure 2. Number of seismic events/day recorded by station SLB on St. Lucia, 17 May-10 June 1990. Courtesy of the Seismic Research Unit, UWI.

"Hypocentral parameters calculated for 34 well-recorded earthquakes show that events were predominantly clustered ~6 km ESE of Qualibou caldera, near Mt. Victorin (altitude 265 m). Focal depths were in the 10-20 km range and magnitudes were generally <mb 2.5. The largest event, of mb 4.6, occurred on 19 May at 1344 and was widely felt throughout St. Lucia. Two other events had magnitudes between 3.0 and 4.0 and were also felt.

"This is the first significant earthquake series that has occurred in St. Lucia since the establishment of a seismic station on the island in 1953, and does not appear to be a foreshock-mainshock- aftershock sequence. The cause of the seismicity is still uncertain but may be due to the intrusion of a small magma body. Temperatures of hot springs in Qualibou caldera did not exhibit any significant variation during the main period of the activity and no episodes of harmonic tremor were recorded."

Information Contacts: W. Ambeh, K. Rowley, L. Lynch, and L. Pollard, UWI.

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

Bulletin Reports - Index


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.

05/1990 (BGVN 15:05) Apparent volcanic earthquakes clustered about 6 km ESE of Qualibou Caldera




Information is preliminary and subject to change. All times are local (unless otherwise noted)


May 1990 (BGVN 15:05) Citation IconCite this Report


Apparent volcanic earthquakes clustered about 6 km ESE of Qualibou Caldera

"Since 17 May 1990, seismic stations in St. Lucia have been registering local earthquakes that appear to be of volcanic origin (both A- and B-type events were observed). About 172 events were detected by seismic station SLB (figure 1) from 17 May to 10 June, with peak activity occurring on 19 and 20 May (figure 2).

Figure (see Caption) Figure 1. Map of St. Lucia, showing earthquake epicenters 17 May-10 June 1990 and locations of seismograph stations. The broken line represents the limits of Qualibou caldera. Courtesy of the Seismic Research Unit, UWI.
Figure (see Caption) Figure 2. Number of seismic events/day recorded by station SLB on St. Lucia, 17 May-10 June 1990. Courtesy of the Seismic Research Unit, UWI.

"Hypocentral parameters calculated for 34 well-recorded earthquakes show that events were predominantly clustered ~6 km ESE of Qualibou caldera, near Mt. Victorin (altitude 265 m). Focal depths were in the 10-20 km range and magnitudes were generally <mb 2.5. The largest event, of mb 4.6, occurred on 19 May at 1344 and was widely felt throughout St. Lucia. Two other events had magnitudes between 3.0 and 4.0 and were also felt.

"This is the first significant earthquake series that has occurred in St. Lucia since the establishment of a seismic station on the island in 1953, and does not appear to be a foreshock-mainshock- aftershock sequence. The cause of the seismicity is still uncertain but may be due to the intrusion of a small magma body. Temperatures of hot springs in Qualibou caldera did not exhibit any significant variation during the main period of the activity and no episodes of harmonic tremor were recorded."

Information Contacts: W. Ambeh, K. Rowley, L. Lynch, and L. Pollard, UWI.

Eruptive History


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


Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1766 Unknown Confirmed 1 Historical Observations Sulphur Springs area

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.

Photo Gallery


The town of Soufriere lies just NW of the 10-km-wide Qualibou caldera. This view from the NW looks across Soufriere Bay to the rounded Terre Blanche lava dome. The western caldera wall lies between the dome and the gentle ridge behind the town. The ridge in the background to the left of Terre Blanche is the back wall of the 3.5 x 5 km caldera, which was formed during powerful eruptions about 32-39,000 years ago.

Photo by Lee Siebert, 1991 (Smithsonian Institution).
See title for photo information.
Hydrothermally altered rocks are exposed over a wide area in the Sulphur Springs thermal area of Qualibou volcano. The thermal area, located in a valley SW of Terre Blanche lava dome, contains 11 hot pools, some of which occasionally produce small steam-driven fountains about 1-m high. Sulphur Springs was the site in 1766 of the only historical eruption of Qualibou. A small explosion deposited ash and cinders over a wide area.

Photo by Lee Siebert, 1991 (Smithsonian Institution).
See title for photo information.
The steep-sided pyramid of the Petit Piton lava dome, the northernmost of St. Lucia's renowned Pitons, rises to the south above Soufriere Bay. The dramatic peak is the eroded plug of a dacitic dome that was emplaced about 250,000 years ago. The 743-m-high dome displays nearly vertical flow banding on all sides. Emplacement of the Pitons preceded formation of the Qualibou caldera about 32-39,000 years ago.

Photo by Lee Siebert, 1991 (Smithsonian Institution).
See title for photo information.
The Pitons, the dramatic landmarks of the island of St. Lucia, are the eroded plugs of two Pleistocene lava domes. Gros Piton (left) and the even steeper Petit Piton (right) are pre-caldera lava domes west and SW of the late-Pleistocene Qualibou caldera. The lower ridge in the right foreground is the SW-most of the 3 Bois d'Indie Franciou andesitic lava domes. They were constructed along a NE-trending fault.

Photo by Lee Siebert, 1991 (Smithsonian Institution).
See title for photo information.
The rounded Terre Blanche lava dome (center) was constructed within the 3.5 x 5 km wide Qualibou caldera. The dome is seen here from the summit of Petit Piton, a pre-caldera lava dome, with the skyline ridge forming the NE caldera wall. Andesitic lava flows and breccias are exposed in the caldera wall. The 450-m-high Terre Blanche dome is one of 3 dacitic lava domes that grew following formation of the caldera about 39,000 years ago.

Photo by Lee Siebert, 1991 (Smithsonian Institution).
See title for photo information.
Gros Piton, seen here from the summit of the Petit Piton, is the southernmost of the twin lava domes that are the hallmark of the island of St. Lucia. The 777-m high and 3-km wide dacitic dome was erupted about 260,000 years ago. Rocks of a small tuff ring are exposed at its base.

Photo by Lee Siebert, 1991 (Smithsonian Institution).
See title for photo information.
The twin lava domes of the Pitons rise above Soufriere Bay on St. Lucia, forming one of the scenic highlights of the West Indies. Petit Piton (left) and Gros Piton (right) are the eroded plugs of 250,000-year-old dacitic lava domes preceding formation of the 3.5 x 5 km Qualibou caldera about 32-39,000 years ago. The only known Holocene activity at Qualibou was a minor phreatic eruption in the Sulfur Springs thermal area in 1766 CE that ejected a thin ash layer over a wide area.

Photo by Lee Siebert, 1991 (Smithsonian Institution).
See title for photo information.

Smithsonian Sample Collections Database


There are no samples for Qualibou in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

Affiliated Sites