Anak Krakatau is a small but highly active volcano located between the Indonesian islands of Java and Sumatra. While most of its eruptions are relatively mild, the volcano can also produce more dangerous activity.

In early September 2026, Anak Krakatau entered a prolonged explosive phase that lasted more than 24 hours, releasing large amounts of volcanic gas and ash. The eruption disrupted air traffic and contributed to poor air quality in several areas, including Jakarta.

Satellite captures Anak Krakatau eruption from space

As explosive activity continued, a satellite observed the eruption on September 5. An image captured by the Operational Land Imager (OLI) aboard the NASA-USGS Landsat 8 satellite shows a bright white plume of volcanic gas rising above a cloud of dark brown volcanic ash.

Observations from the VIIRS (Visible Infrared Imaging Radiometer Suite) aboard the Suomi National Polar-orbiting Partnership satellite revealed that the volcanic material had spread across a wider area. View a wider perspective of the eruption.

By September 6, Indonesia’s meteorological agency reported that volcanic ash had reached altitudes of up to 6,000 meters (20,000 feet) east of the volcano and up to 15,000 meters (50,000 feet) to the west.

Volcanic ash cloud grounds nearly 3,000 flights

High concentrations of volcanic ash in the atmosphere forced the temporary closure of eight airports across Java and Sumatra. According to news coverage, nearly 3,000 flights to and from the affected areas were grounded.

Ash also fell in populated areas. The Indonesia Humanitarian Coordination Platform (IHCP) reported that communities east of Anak Krakatau, including Jakarta and other parts of West Java, were particularly affected.

Volcanic ash can irritate the respiratory system, eyes and skin. IHCP noted that the risks associated with volcanic ash differ from those caused by smoke from peatland fires elsewhere in Indonesia. Volcanic ash and wildfire smoke have different particle properties, move through the atmosphere in different ways and require different protection measures.

Anak Krakatau remains on high alert

Anak Krakatau continued to rumble, but its sustained explosive activity subsided on September 6. The volcano’s activity returned to a more typical pattern, including periodic eruptions of ash and other volcanic material known as Strombolian eruptions.

Although airport operations later resumed, Anak Krakatau remains at Indonesia’s second-highest volcano alert level, a status it has held since early July.

NASA Earth Observatory image by Michala Garrison using Landsat data from the United States Geological Survey, VIIRS data from NASA, and GIBS/Worldview data from the Suomi National Polar-orbiting Partnership.