Earthquake swarm began in mid-2009

Morne aux Diables is the northermost of the nine volcanic centers on the island of Dominica (Lindsay and others, 2005) (figure 1). The complex (figures 2 and 3) is comprised of five intact andesitic crystal rich lava domes that form a central depression. Within the depression, a 'Cold Soufrière' is evident with hydrothermally altered rocks and many small bubbling pools. No historical eruptions are known, although the volcano has a youthful appearance, and activity at flank domes likely continued into the late Pleistocene and Holocene (Lindsay and others, 2005). Robert Watts, at the University of the West Indies (UWI) Seismic Research Centre, reported that the volcano remains quiet, though with noteworthy seismicity in 2009 and 2010.

Figure 1. Geologic map of Dominica, West Indies, showing the Morne aux Diables complex at the N end of island. From N to S, generally, these nine centers are Morne aux Diables, Morne Diablotins, Morne Trois Pitons, Wotten Waven caldera, Valley of Desolation, Grande Soufrière Hills, Morne Watt, Morne Anglais, and Morne Plat Pays. Original map by Roobol and Smith (2004a) (see Roobol and Smith, 2004b); copied from Lindsey and others (2005).

Figure 2. Panoramic view from E. Cabrits dome looking E to the Morne aux Diables complex. Morne Aux Diables is on the left and Morne Destinee to the right. Courtesy of Richard Arculus and Robert Watts.

Figure 3. Photograph of the Morne aux Diables complex, taken from near Portsmith Town. The topographic high Morne Aux Diables is on the left; Morne Heritiers, center; and Morne Destinee, right. Courtesy of Robert Watts.

Watts, and Lindsay and others (2005), reported that in 2002 SeaBeam bathymetry highlighted a double peaked lava dome (known informally as Twin Peaks) on the sea floor a few kilometers off the northern coastline of Dominica. The summit of the higher dome (at 15.671?N, 61.476?W) was 153 m below sea level. This northern coastline terminating the N end of the Morne aux Diables complex forms a linear cliff that may represent a fault.

Seismic swarm during 2009-2010. The most common area of seismicity, as noted by Watts and others (2012a and 2012b), has been in the SE sector of Dominica. In the north there were spurts in activity in 1841, 1893, 2000, and a particularly intense week-long burst of more than 500 earthquakes in 2003. Following six years of low-level activity, a nearly continuous series of earthquakes was recorded beneath the central area of Morne aux Diables beginning in June 2009. The seismic swarm continued through at least 2010 with variations in activity that are consistent with volcano-tectonic (VT) activity.

The VT series reached a peak in December 2009, with many events felt by villagers on the flanks of the volcano, but earthquake activity afterwards gradually been diminishing. Beginning in December 2010, VT earthquakes exhibited a gradual shallowing with time (a few approaching 1 km depth), indicating that they are related to a vertical re adjustment of the stresses below the volcano, most likely caused by magma movement (Watts and others, 2012b).

References. Lindsay, J.M., Smith, A.L., Roobol, M.J., and Stasiuk, M.V., 2005, Dominica in Lindsay, J.M., Robertson, R.E.A., Shepherd, J.B. and Ali, S. (eds), Volcanic Hazard Atlas of the Lesser Antilles, Seismic Research Centre, The University of the West Indies, Trinidad & Tobago, West Indies, p. 1-48.

Roobol, M.J., and Smith, A.L., 2004a. Volcanology of Saba and St. Eustatius, northern Lesser Antilles, Amsterdam: Royal Netherlands Academy of Arts and Letters, 320 p.

Roobol, M.J., and Smith, A.L., 2004b, Geologic map of Dominica, West Indies (URL: http://www.caribbeanvolcanoes.com/dominica/content/dominicamap.pdf).

Watts, R.B., Robertson, R.E., Abraham, W., Cole, P., de Roche, T., Edwards, S., Higgins, M., Johnson, M., Joseph, E.P., Latchman, J., Lynch, L., Nisha, N., Ramsingh, C., and Stewart, R.C., 2012a , Elevated seismic activity beneath the slumbering Morne aux Diables volcano, Northern Dominica and the monitoring role of the Seismic Research Center, poster presentation at the 2012 American Geophyhsical Union Fall Meeting, San Francisco, CA.

Watts, R., Robertson, R., Abraham, W., Cole, P., Corriette, D., de Roche, T., Edwards, S., Higgins, M., Issacs, N., Johnson, M., Joseph, E., Latchman, J., Lynch, L., Nisha, N., Phillip, B., Ramsingh, C., and Stewart, R., 2012b, Elevated seismic activity beneath the slumbering Morne aux Diables volcano, northern Dominica, poster on UWISRC web (URL: http://www.uwiseismic.com/Downloads/Dominica_activity_Poster_Watts.pdf).

Information Contacts: Robert B. Watts, The University of the West Indies (UWI) Seismic Research Centre, St. Augustine, Trinidad & Tobago, West Indies (URL: http://www.uwiseismic.com/).

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

March 2013 (BGVN 38:03) Cite this Report

Earthquake swarm began in mid-2009

Morne aux Diables is the northermost of the nine volcanic centers on the island of Dominica (Lindsay and others, 2005) (figure 1). The complex (figures 2 and 3) is comprised of five intact andesitic crystal rich lava domes that form a central depression. Within the depression, a 'Cold Soufrière' is evident with hydrothermally altered rocks and many small bubbling pools. No historical eruptions are known, although the volcano has a youthful appearance, and activity at flank domes likely continued into the late Pleistocene and Holocene (Lindsay and others, 2005). Robert Watts, at the University of the West Indies (UWI) Seismic Research Centre, reported that the volcano remains quiet, though with noteworthy seismicity in 2009 and 2010.

Figure 1. Geologic map of Dominica, West Indies, showing the Morne aux Diables complex at the N end of island. From N to S, generally, these nine centers are Morne aux Diables, Morne Diablotins, Morne Trois Pitons, Wotten Waven caldera, Valley of Desolation, Grande Soufrière Hills, Morne Watt, Morne Anglais, and Morne Plat Pays. Original map by Roobol and Smith (2004a) (see Roobol and Smith, 2004b); copied from Lindsey and others (2005).

Figure 2. Panoramic view from E. Cabrits dome looking E to the Morne aux Diables complex. Morne Aux Diables is on the left and Morne Destinee to the right. Courtesy of Richard Arculus and Robert Watts.

Figure 3. Photograph of the Morne aux Diables complex, taken from near Portsmith Town. The topographic high Morne Aux Diables is on the left; Morne Heritiers, center; and Morne Destinee, right. Courtesy of Robert Watts.

Watts, and Lindsay and others (2005), reported that in 2002 SeaBeam bathymetry highlighted a double peaked lava dome (known informally as Twin Peaks) on the sea floor a few kilometers off the northern coastline of Dominica. The summit of the higher dome (at 15.671?N, 61.476?W) was 153 m below sea level. This northern coastline terminating the N end of the Morne aux Diables complex forms a linear cliff that may represent a fault.

Seismic swarm during 2009-2010. The most common area of seismicity, as noted by Watts and others (2012a and 2012b), has been in the SE sector of Dominica. In the north there were spurts in activity in 1841, 1893, 2000, and a particularly intense week-long burst of more than 500 earthquakes in 2003. Following six years of low-level activity, a nearly continuous series of earthquakes was recorded beneath the central area of Morne aux Diables beginning in June 2009. The seismic swarm continued through at least 2010 with variations in activity that are consistent with volcano-tectonic (VT) activity.

The VT series reached a peak in December 2009, with many events felt by villagers on the flanks of the volcano, but earthquake activity afterwards gradually been diminishing. Beginning in December 2010, VT earthquakes exhibited a gradual shallowing with time (a few approaching 1 km depth), indicating that they are related to a vertical re adjustment of the stresses below the volcano, most likely caused by magma movement (Watts and others, 2012b).

References. Lindsay, J.M., Smith, A.L., Roobol, M.J., and Stasiuk, M.V., 2005, Dominica in Lindsay, J.M., Robertson, R.E.A., Shepherd, J.B. and Ali, S. (eds), Volcanic Hazard Atlas of the Lesser Antilles, Seismic Research Centre, The University of the West Indies, Trinidad & Tobago, West Indies, p. 1-48.

Roobol, M.J., and Smith, A.L., 2004a. Volcanology of Saba and St. Eustatius, northern Lesser Antilles, Amsterdam: Royal Netherlands Academy of Arts and Letters, 320 p.

Roobol, M.J., and Smith, A.L., 2004b, Geologic map of Dominica, West Indies (URL: http://www.caribbeanvolcanoes.com/dominica/content/dominicamap.pdf).

Watts, R.B., Robertson, R.E., Abraham, W., Cole, P., de Roche, T., Edwards, S., Higgins, M., Johnson, M., Joseph, E.P., Latchman, J., Lynch, L., Nisha, N., Ramsingh, C., and Stewart, R.C., 2012a , Elevated seismic activity beneath the slumbering Morne aux Diables volcano, Northern Dominica and the monitoring role of the Seismic Research Center, poster presentation at the 2012 American Geophyhsical Union Fall Meeting, San Francisco, CA.

Watts, R., Robertson, R., Abraham, W., Cole, P., Corriette, D., de Roche, T., Edwards, S., Higgins, M., Issacs, N., Johnson, M., Joseph, E., Latchman, J., Lynch, L., Nisha, N., Phillip, B., Ramsingh, C., and Stewart, R., 2012b, Elevated seismic activity beneath the slumbering Morne aux Diables volcano, northern Dominica, poster on UWISRC web (URL: http://www.uwiseismic.com/Downloads/Dominica_activity_Poster_Watts.pdf).

Information Contacts: Robert B. Watts, The University of the West Indies (UWI) Seismic Research Centre, St. Augustine, Trinidad & Tobago, West Indies (URL: http://www.uwiseismic.com/).