The 2004 Les Saintes earthquake occurred at on November 21, 2004 with a moment magnitude of 6.3 and maximum
European macroseismic intensity of VIII (''Heavily damaging''). The shock was named for
Îles des Saintes
The Îles des Saintes (; "Islands of the Female Saints"), also known as Les Saintes, is a group of small islands in the archipelago of Guadeloupe, an overseas department of France. It is part of the Canton of Trois-Rivières and is divided int ...
"Island of the Saints", a group of small islands to the south of
Guadeloupe
Guadeloupe (; ; gcf, label=Antillean Creole, Gwadloup, ) is an archipelago and overseas department and region of France in the Caribbean. It consists of six inhabited islands—Basse-Terre, Grande-Terre, Marie-Galante, La Désirade, and the ...
, which is an
overseas department
The overseas departments and regions of France (french: départements et régions d'outre-mer, ; ''DROM'') are departments of France that are outside metropolitan France, the European part of France. They have exactly the same status as mainlan ...
of
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
. Although it occurred near the
Lesser Antilles subduction zone
The Lesser Antilles subduction zone is a convergent plate boundary on the seafloor along the eastern margin of the Lesser Antilles Volcanic Arc. In this subduction zone, oceanic crust of the South American Plate is being subducted under the Cari ...
, this was an
intraplate, normal fault event. It resulted in one death, 13 injuries, and 40 people being made homeless, but the overall damage was considered moderate. A small, nondestructive tsunami was reported, but run-up and inundation distances were difficult to measure due to a storm that occurred on the day of the event. Unusual effects at a volcanic lake on Dominica were also documented, and an aftershock caused additional damage three months later.
Tectonic setting
While the northern and southern boundaries of the
Caribbean Plate
The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the north coast of South America.
Roughly 3.2 million square kilometers (1.2 million square miles) in area, the Caribbean Plate borders ...
are complex and diffuse, with zones of seismicity stretching several hundred kilometers across, the eastern boundary is that of the
Lesser Antilles subduction zone
The Lesser Antilles subduction zone is a convergent plate boundary on the seafloor along the eastern margin of the Lesser Antilles Volcanic Arc. In this subduction zone, oceanic crust of the South American Plate is being subducted under the Cari ...
. This long
subduction zone
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...
lacks a uniform curve and has an average
dip of 50–60°. The largest known earthquake on the plate interface was a M7.5–8.0
event in 1843, but it did not generate a large tsunami. In opposition, the three largest events between 1950 and 1978 were intraplate normal faulting events.
Earthquake
The mainshock and the primary aftershock occurred on the previously mapped Roseau Fault, a , northeast-dipping normal fault that forms the western portion of the northwest-trending Les Saintes channel
graben
In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults.
Etymology
''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic contex ...
within the overriding
North American Plate
The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...
. Late 1990s bathymetric studies showed that it had vertical
fault scarp
A fault scarp is a small step or offset on the ground surface where one side of a fault has moved vertically with respect to the other. It is the topographic expression of faulting attributed to the displacement of the land surface by movement al ...
s approaching . The type of slip was primarily extensional, but included a small amount of left-lateral slip, and may have contributed to hydrological/volcanic effects that were observed on the island of
Dominica
Dominica ( or ; Kalinago: ; french: Dominique; Dominican Creole French: ), officially the Commonwealth of Dominica, is an island country in the Caribbean. The capital, Roseau, is located on the western side of the island. It is geographically ...
, where a flooded
fumarole
A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...
drained twice.
Damage
A maximum intensity of VIII (''Heavily damaging'') on the
European macroseismic scale
The European macroseismic scale (EMS) is the basis for evaluation of seismic intensity in European countries and is also used in a number of countries outside Europe. Issued in 1998 as an update of the test version from 1992, the scale is referred ...
was recorded at
Terre-de-Haut
Terre-de-Haut (; gcf, label=Antillean Creole, Tèdého) is a commune in the French overseas department of Guadeloupe, including Terre-de-Haut Island and a few other small uninhabited islands of the archipelago (''les Roches Percées''; ''Îlet ...
, where some serious damage occurred to a school, a church, and some homes near the sugar loaf. The same intensity was observed at
Terre-de-Bas
Terre-de-Bas (; gcf, label=Antillean Creole, Tèdéba) is a commune in the French overseas department and region of Guadeloupe, in the Lesser Antilles. Terre-de-Bas is made up of Terre-de-Bas Island and several uninhabited islands and islets ...
, where damage was moderate and non-structural in nature. At
Petite-Anse, a small area contained some damaged walls, but no complete collapses occurred. At
Grand-Bourg
Grand-Bourg is a commune on the island of Marie-Galante, in the French overseas region and department of Guadeloupe in the Lesser Antilles Caribbean. It is located in the southwest of Marie-Galante, and is the most populous of the three commune ...
on the island of
Marie-Galante
Marie-Galante ( gcf, label=Antillean Creole, Mawigalant) is one of the islands that form Guadeloupe, an overseas department of France. Marie-Galante has a land area of . It had 11,528 inhabitants at the start of 2013, but by the start of 2018 ...
(where the intensity was deemed to be VI–VII (''Slightly damaging–Damaging'')) the town hall, a church, and a college were
red-tagged (unsuitable for use). The same intensity was assigned to the nearby commune of
Saint-Louis, where the newly built town hall had visible cracks and the church was closed due to the potential of aftershocks breaking stained glass windows.
[ ]
Boiling Lake
In the weeks following the mainshock, no abnormal geochemical or seismic activity was observed at
La Grande Soufrière
La Grande Soufrière ( en, "big sulfur outlet"), is an active stratovolcano on the French island of Basse-Terre, in Guadeloupe. It is the highest mountain peak in the Lesser Antilles, rising 1,467 m high.
The last magmatic eruption was in ...
(an active
stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
) on Guadeloupe, but on southern Dominica near the Valley of Desolation, a flooded fumarole known as Boiling Lake was discovered empty by tourists on
Christmas Day
Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the Christian liturgical year, ...
. The deep lake lies in an active geothermal area and is normally stable in terms of temperature () and water level. By mid-February, the lake was full again, but its temperature had not returned to normal. The water level dropped again following the M5.8 aftershock on February 14.
[
]
Aftershocks
By mid-February, aftershock activity had essentially ceased, with events becoming increasingly far apart. On February 14, a strong and slightly-damaging aftershock occurred. This was also a normal slip event that occurred about northwest of the November 21 mainshock. The damage was minimal, with cracks developing on the roads, some broken water pipes, and wall and roof damage—including at some locations that were damaged during the mainshock.[
]
Tsunami
A small tsunami took place following the shock, and while no tide gauges captured the event, scientists were on scene several days later to investigate. A large storm occurred on the day of the event, and this might have prevented visual observation of the tsunami, but witnesses on Guadeloupe reported the sea level dropped "a few" to as many as . At Anse des Mûriers on Îles des Saintes, a ship captain reported that three minutes after the earthquake the sea dropped about and also receded from the coast about . In Anse Rodrigue, the tsunami had a run-in distance of . Investigators documented a run-up at Anse Pajot, but these findings were difficult to distinguish from the storm surge
A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the n ...
. A maximum run-up of was recorded at Grande-Anse beach and L'anse Rodrigue on Terre-de-Haut Island, and on Grande-Anse Terre-de-Bas Island
Terre-de-Bas Island (officially in French: Terre-de-Bas des Saintes ''(literally: Lowland of les Saintes)'') is an island in the Îles des Saintes archipelago, in the Lesser Antilles.
It belongs to the commune (municipality) of Terre-de-Bas in the ...
. The tsunami was recorded as far as from the epicenter, at Capesterre-Belle-Eau
Capesterre-Belle-Eau is a commune in the French overseas region and department of Guadeloupe, in the Lesser Antilles. It is located in the south-east of Basse-Terre Island. Capesterre-Belle-Eau covers an area of 103.3 km2 (39.884 sq mi). Th ...
.
See also
*Geography of Dominica
Dominica is an island in the Caribbean Sea, located about halfway between the French islands of Guadeloupe (to the north) and Martinique (to the south). Its coordinates are 15 25 N, 61 20 W. It is known as "The Nature Island of the Caribbean" ...
*Lesser Antilles
The Lesser Antilles ( es, link=no, Antillas Menores; french: link=no, Petites Antilles; pap, Antias Menor; nl, Kleine Antillen) are a group of islands in the Caribbean Sea. Most of them are part of a long, partially volcanic island arc betwe ...
* List of earthquakes in 2004
*List of earthquakes in the Caribbean
Major earthquakes in the Caribbean are infrequent and are sometimes accompanied by tsunami.
Earthquakes
See also
* List of earthquakes in Cuba
* List of earthquakes in the Dominican Republic
* List of earthquakes in Haiti
* List of earthquake ...
References
External links
M6.3 - Dominica region, Leeward Islands
– United States Geological Survey
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...
*
{{Earthquakes in the Caribbean
2004 earthquakes
2004 tsunamis
2004 in the Caribbean
2004 in Guadeloupe
November 2004 events in North America
Natural disasters in Guadeloupe
Earthquakes in the Caribbean
Natural disasters in Dominica