Anak Krakatau, a small but highly active volcano situated between the Indonesian islands of Java and Sumatra, erupted for more than 24 hours in early September 2026. The eruption sent volcanic ash as high as 15,000 meters (about 50,000 feet) into the atmosphere, disrupting air travel and causing poor air quality in several regions, including Jakarta. The event was observed by satellites on September 5, with the OLI (Operational Land Imager) aboard the NASA-USGS Landsat 8 satellite capturing 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 showed the spread of volcanic material across a wide area. By September 6, Indonesia’s meteorological agency reported that volcanic ash had reached altitudes of up to 6,000 meters (about 20,000 feet) east of the volcano and as high as 15,000 meters (about 50,000 feet) to the west. The high concentration of ash in the atmosphere led to the temporary closure of eight airports across Java and Sumatra. News reports indicated that nearly 3,000 flights into and out of the affected region were disrupted. Ash also fell in populated areas, with the Indonesian Humanitarian Coordination Platform (IHCP) noting that communities east of Anak Krakatau, including Jakarta and parts of West Java, were particularly affected. Volcanic ash can pose health risks, as it may irritate the respiratory system, eyes, and skin. The IHCP emphasized that the hazard from volcanic ash differs from the smoke produced by peatland fires in other parts of Indonesia. Volcanic ash and wildfire smoke have different particle properties and travel through the atmosphere in different ways, requiring distinct protective measures. The volcano’s explosive activity weakened on September 6, although Anak Krakatau continued to rumble. Its activity shifted back to a more typical pattern of Strombolian eruptions, which involve periodic bursts of ash and volcanic material. Airports had resumed operations by September 8, but Anak Krakatau remained at the second-highest alert level on Indonesia’s volcanic warning scale. This status had been in place since early July, indicating that the volcano was still considered a significant threat, though not in a state of imminent danger. The event highlighted the ongoing activity of one of Indonesia’s most closely monitored volcanoes and the potential for eruptions to disrupt both the environment and human activity in the region.