O que fez a erupção de vulcão em Tonga ser tão explosiva
The Eruption of Hunga-Tonga Hunga-Ha'apai: A Global Alert
Overview of the Eruption
- On January 15, the underwater volcano Hunga-Tonga Hunga-Ha'apai erupted, causing a tsunami that impacted Tonga with waves several meters high. The capital, Nuku'alofa, is located just 65 km from the volcano.
- The government described the situation as an unprecedented disaster. The explosion's sound was heard as far away as the United States, prompting tsunami alerts in countries across the Pacific, including Japan and Chile.
Scientific Inquiry into the Eruption
- Camilla Veras Mota from BBC News Brasil discusses ongoing investigations into two critical questions: what caused such a powerful eruption and how did it lead to a tsunami?
- The volcano is formed by two islands and is situated in a seismically active zone. It rises only 100 meters above sea level but extends 1,800 meters underwater.
Mechanism of Explosion
- The eruption occurs within a submerged caldera—a crater-like depression—where magma rich in gases at around 1,000 degrees Celsius interacts violently with cold seawater.
- This interaction leads to explosive reactions where fragments of magma create new explosions at supersonic speeds. The eruption lasted for eight minutes and produced an ash column reaching 20 km high and spanning 260 km in diameter.
Historical Context and Frequency
- Geologist Shane Cronin notes that significant eruptions at this site occur approximately every 900 years. Previous major eruptions were recorded in 1100 AD and another about 1800 years ago.
Tsunami Generation Factors
- Geologist Daniel Melnick identifies two main causes for the tsunami: volcanic rocks ejected into the ocean contributing to water displacement and potential underwater collapses pushing water upward.