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

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 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.

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.