Anak Krakatau is a small but highly active volcano located between the Indonesian islands of Java and Sumatra. Its eruptions are often relatively modest, but the volcano is also capable of producing much more hazardous activity. In early September 2026, Anak Krakatau entered a prolonged explosive phase that lasted for more than 24 hours, sending large amounts of gas and ash into the sky. The eruption disrupted air travel and contributed to poor air quality in several areas, including Jakarta.

Satellites Capture the Eruption From Space

Satellites observed the eruption on September 5 as explosive activity continued at the volcano. One image (above), collected by the OLI (Operational Land Imager) aboard the NASA-USGS Landsat 8 satellite, shows a bright white plume of volcanic gas rising above a darker brown cloud of ash.

A broader view from the VIIRS (Visible Infrared Imaging Radiometer Suite) aboard the Suomi NPP satellite revealed volcanic material spreading across a much wider area.

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

Ash Cloud Disrupts Thousands of Flights

The high concentration of volcanic ash in the atmosphere forced the temporary closure of eight airports across Java and Sumatra. According to news reports, nearly 3,000 flights into and out of the affected region were disrupted.

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

Volcanic ash can pose health concerns because it may irritate the respiratory system, eyes, and skin. The IHCP noted that the hazard differs from the smoke produced by peatland fires elsewhere in Indonesia. Volcanic ash and wildfire smoke have different particle properties, travel through the atmosphere in different ways, and require different protective measures.

Anak Krakatau Remains on High Alert

The volcano's sustained explosive activity weakened on September 6, although Anak Krakatau continued to rumble. Its activity shifted back toward a more typical pattern of Strombolian eruptions, which involve periodic bursts of ash and other volcanic material.

Airports had resumed operation by September 8. Even so, Anak Krakatau remained at the second-highest alert level on Indonesia's volcanic warning scale, a status it has held since early July.

NASA Earth Observatory images by Michala Garrison, using Landsat data from the U.S. Geological Survey, and VIIRS data from NASA EOSDIS LANCE, GIBS/Worldview, and the Suomi National Polar-orbiting Partnership.