About Don Joao de Castro Bank
Don Joao de Castro Bank is a shield rising to -13 meters (-43 feet) in Portugal's Atlantic Ocean Volcanic Regions. Its last known eruption was in 1720 CE. The volcano has produced 2 recorded eruptions, with a maximum Volcanic Explosivity Index (VEI) of 3.
Geography & Climate
Don Joao de Castro Bank is located in Portugal, within the Azores-Terceira Rift Volcanic Province of the broader Atlantic Ocean Volcanic Regions. Situated at 38.23° N, 26.63° W in the Northern Hemisphere, the volcano lies within a temperate climate zone. With an elevation of -13 meters — below sea level — Don Joao de Castro Bank is a submarine or submerged volcanic feature. Submarine volcanoes make up the majority of Earth's volcanic activity, though most eruptions go unobserved beneath the ocean surface. The volcanic landform is characterized as a shield, which describes the physical shape and structure of the volcanic edifice as observed from the surface.
Geological Context
Don Joao de Castro Bank is situated along a rift zone, where tectonic plates are pulling apart. As the crust thins and fractures, magma rises to fill the gap, creating volcanic activity. Rift volcanism typically produces more fluid lava flows rather than explosive blasts, which means communities near Don Joao de Castro Bank in Portugal generally face slower-moving hazards like lava flows and ground fissures rather than sudden pyroclastic events. However, rift volcanoes can still generate significant ash emissions and gas releases that affect local air quality. The dominant rock type is basalt / picro-basalt, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.
Eruption History Summary
Don Joao de Castro Bank has 2 recorded eruptions in the geological database, spanning from 1720 CE to 1997 CE. The most powerful recorded event was a severe eruption capable of regional ash fall and pyroclastic flows in 1720 CE, reaching VEI 3 on the Volcanic Explosivity Index. These eruptions span roughly 277 years of volcanic history. The most recent eruption in 1997 CE places this volcano within the modern era of volcanological observation.
Significance
With a maximum recorded VEI of 3, Don Joao de Castro Bank has produced eruptions capable of generating pyroclastic flows and significant ash fall in the surrounding area. While not among the largest eruptions globally, VEI 3 events pose serious hazards to local populations and can disrupt regional air travel. Given its recent activity, Don Joao de Castro Bank is closely monitored by geological survey organizations to provide early warning of future unrest.
GVP Reference Summary
Don Joao de Castro Bank is a large submarine volcano that rises to within 13 m of the ocean surface roughly halfway between Terceira and San Miguel Islands. Pillow lavas form the base of the volcano, which is capped by basaltic hyaloclastites. A submarine eruption during December 1720 produced an ephemeral island that attained a length of 1.5 km and a height of about 250 m before it was eroded beneath the surface two years later. The volcano (also spelled Dom Joao de Castro) was named after the Portuguese hydrographic survey vessel that surveyed the bank in 1941. Two youthful craters, one tephra covered and the other sediment free, are located on the NW flank. The submarine volcano has a shallow fumarole field and remains seismically active.
— Smithsonian Institution, Global Volcanism Program
2 Recorded Eruptions
| Year | VEI | Type | Area |
|---|---|---|---|
| 1997 | 0 | Uncertain Eruption | NW of Don Joao de Castro Bank |
| 1720 | 3 | Confirmed Eruption | — |
Real-Time Data
USGS Alert Level
Thermal Anomalies
Frequently Asked Questions About Don Joao de Castro Bank
Is Don Joao de Castro Bank an active volcano?+
Don Joao de Castro Bank is classified as active based on credible evidence of past eruptions. Although its last known eruption was in 1720 CE, volcanologists consider it capable of erupting again.
When did Don Joao de Castro Bank last erupt?+
The most recent recorded eruption of Don Joao de Castro Bank occurred in 1997 CE with a Volcanic Explosivity Index (VEI) of 0. The eruption was classified as a "Uncertain Eruption." Don Joao de Castro Bank has 2 recorded eruptions in total.
How high is Don Joao de Castro Bank?+
Don Joao de Castro Bank has a summit elevation of -13 meters (-43 feet) above sea level. With an elevation of -13 meters (below sea level), this is a submarine or submerged volcanic feature.
What type of volcano is Don Joao de Castro Bank?+
Don Joao de Castro Bank is classified as a Shield. Shield volcanoes have distinct geological characteristics that set them apart from other volcanic types.
Where is Don Joao de Castro Bank located?+
Don Joao de Castro Bank is located in Portugal, in the Atlantic Ocean Volcanic Regions. More specifically, it lies within the Azores-Terceira Rift Volcanic Province. Its exact coordinates are 38.230° latitude, -26.630° longitude.
Is it safe to visit Don Joao de Castro Bank?+
Don Joao de Castro Bank can generally be visited, but as with any volcano, visitors should check local conditions and any advisory notices before traveling. Portugal may have specific regulations for accessing volcanic areas. Guided tours are often the safest and most informative way to experience a volcano.
