Description

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Context

The sudden eruption of Costa Rica Poás volcano sent a towering 3 km high ash plume into sky disrupting tourism & prompting geohazard alerts across region.

Poás Volcano

Feature	Details
Type	Stratovolcano (Composite)
Location	Alajuela Province, Central Costa Rica
Protected Area	Poás Volcano National Park
Elevation	2,708 meters above sea level
Crater Characteristics	~1.5 km wide, ~300 meters deep; among largest active craters globally
Volcanic Structure	Irregular composite with multiple eruptive centers; includes several large collapse craters
Basal Area	~400 sq. km
Volcanic Activity	One of most active in Costa Rica; episodes of ash, gas & phreatic eruptions
Gas Emissions	SO₂ & acidic gases cause acid rain & ecosystem damage (notable since 1989)
Crater Lake	Known as Laguna Caliente; highly acidic, drying up as of 2024, increasing eruption frequency
Eruption History	Frequent activity with major events in 1910, 1953, 2017 & minor eruptions continuing into 2025
Recent Activity (2024–2025)	Crater lake drying, strong sulfurous emissions, ash columns up to 3 km, rock ejections
Impact on Ecosystem	Acid rain affects highland flora, mosses & agricultural crops
Tourism Impact	A popular destination with restricted access during high volcanic activity

Costa Rica’s Volcanic Landscape

Volcano	Elevation (m)	Type	Last Known Activity	Notable Features
Poás	2,708	Stratovolcano	2025	Large crater, acid lake, high gas emissions
Arenal	1,670	Stratovolcano	Dormant since 2010	Previously most active; iconic symmetrical cone
Irazú	3,432	Stratovolcano	Active	Highest active volcano in Costa Rica; crater lake
Turrialba	3,340	Stratovolcano	Ongoing	Recent gas-rich eruptions affecting San José airport
Rincón de la Vieja	1,916	Complex volcano	Active	Hydrothermal activity, crater lake, frequent phreatic eruptions
Barva	2,906	Stratovolcano	Dormant	Covered in cloud forest; part of Braulio Carrillo National Park
Tenorio	1,916	Stratovolcano	Dormant	Famous for Río Celeste’s turquoise waters from volcanic minerals

Tectonic setting & Volcanic structure of Costa Rica Volcanoes

Aspect	Details
Tectonic Plate Setting	Costa Rica lies at convergent boundary where Cocos Plate subducts beneath Caribbean Plate along Middle America Trench.
Subduction Characteristics	Angle Moderate-angle subduction. Rate ~9 cm/year. Leads to magma generation in mantle wedge rising to form stratovolcanoes.
Volcanic Arc	Costa Rica is part of Central American Volcanic Arc (CAVA) formed by consistent subduction-related volcanism.
Volcano Type	Stratovolcanoes (Composite volcanoes) tall, conical with alternating layers of lava, ash & pyroclastics.
Structure (Poás)	Irregular, complex stratovolcano. Multiple eruptive centers. Basal area ~400 sq.km. Crater ~1.5 km wide, 300 m deep.
Volcanic Activity	Explosive eruptions due to high viscosity magma & gas content. Presence of crater lakes increases potential for phreatic/phreatomagmatic eruptions.
Recent Activity (Poás)	Increasing gas emissions, crater lake drying (2024–2025). Ash plumes, acid rain, small explosive events.
Environmental Effects	Acid rain from sulfur emissions. Damage to forest, crops & national parks. -Disruption of tourism & local livelihoods.
Hazard Monitoring	Monitored by OVSICORI (Volcanological & Seismological Observatory of Costa Rica) using seismic, gas & thermal sensors.
Disaster Risk	High due to proximity to population centers, high tourist footfall, acid lake hazard & frequent eruptive episodes.

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Sources: MSN

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PRACTICE QUESTION

Q.Costa Rica’s volcanic geography offers both opportunities & challenges to its sustainable development. Discuss geological factors that make Costa Rica volcanically active.