Guadeloupe

Guadeloupe is a French overseas department in the northern Lesser Antilles, situated directly above the most active segment of the Lesser Antilles [[subduction-zone]], where the North American oceanic plate dives westward beneath the Caribbean Plate at approximately 2 centimetres per year. The department consists of two main islands — Basse-Terre and Grande-Terre — separated by the Rivière Salée, a narrow marine channel. Basse-Terre is a geologically young volcanic island dominated by La Grande Soufrière (1,467 metres), an active stratovolcano that last erupted in 1976–1977 and remains one of the most closely monitored volcanoes in the Caribbean. Grande-Terre, by contrast, is built on older coral limestone and experiences lower amplitudes of local seismicity. The subduction interface lies approximately 100 to 150 kilometres to the east, and the volcanic arc stands directly above the zone of maximum slab-fluid release into the overlying mantle wedge. Seismic hazard in Guadeloupe is rated very high — among the highest in the Caribbean for a populated territory.

The 1843 Guadeloupe earthquake stands as one of the largest and most destructive earthquakes ever recorded in the Caribbean region. Striking on 8 February 1843, the event is estimated at [[magnitude]] 8.0 — a great earthquake by any definition — with an [[epicenter]] offshore in the subduction zone to the east of the islands. In Guadeloupe, the earthquake destroyed an estimated 5,000 buildings and killed approximately 3,000 people; destruction extended across the northern Lesser Antilles from Montserrat to Saint-Martin. In the instrumental era, Guadeloupe has experienced numerous M5–6 subduction interface and intraslab earthquakes, including a damaging M6.3 event in 2004. Volcanic-tectonic earthquake swarms beneath La Grande Soufrière occur periodically, most notably a swarm in 2018–2021 that prompted intensive monitoring and public alert protocols. The island generates [[seismic-wave]] energy from both the [[subduction-zone]] system and the volcanic edifice itself.

Guadeloupe's geological history spans approximately 6 million years of arc volcanism. Basse-Terre is constructed of successive volcanic sequences from south (older, deeply eroded) to north (younger, more active), with La Grande Soufrière representing the most recent and still-active volcanic centre. The volcanic rocks are overlain by thick sequences of pyroclastic deposits, lahars, and lava flows that can [[liquefaction]] when saturated. Grande-Terre's carbonate platform records Miocene to Quaternary marine transgression-regression cycles. The OVSG-IPGP (Volcanological Observatory of Guadeloupe, Institut de Physique du Globe de Paris) operates the primary seismic and volcanic monitoring network, providing real-time data to French civil protection authorities. [[tsunami]] warning is coordinated through the CENALT (French Tsunami Warning Centre), reflecting the territory's exposure to both locally generated and Caribbean-wide tsunami sources.