Indonesian authorities raised the alert level of the Anak Krakatoa volcano Thursday in the wake of last weekend's eruption-triggered tsunami that killed 430 and left 159 others missing.

Axar.az reports citing Al Jazeera.

The Volcanology and Geological Disaster Mitigation Agency said the alert status at Mt. Anak Krakatau was raised to Level 3, one notch below the highest level, at 6 a.m., Japan’s Kyodo News Agency reported. Flights around the volcano have also been rerouted.

The eruption of the volcano around 9:30 p.m. local time Saturday caused a section of the crater to collapse and slide into the ocean, sending waves up to 16 feet (5 meters) high crashing into the coast on the Sunda Strait.

Hundreds of homes, shops, and vessels were also destroyed.

Indonesia lies within the Pacific Ocean’s "Ring of Fire," where tectonic plates collide and cause frequent seismic and volcanic activity.

In September, a 7.4-magnitude earthquake struck the country's Sulawesi Island, triggering a tsunami that towered up to 10 feet (3 meters) high and killed over 2,000 people.

The IHH was one of the first aid groups in Turkey to reach the victims immediately after the earthquake and tsunami.

On Dec. 26, 2004, a magnitude 9.1 earthquake struck the eastern coast of Sumatra, triggering a tsunami that killed around 230,000 people as it tore along the coasts of Sri Lanka, India, Malaysia, Indonesia, and Thailand.