Japan Assesses Whether Anak Krakatau Eruption Could Trigger a Tsunami

Jakarta, CNBC Indonesia – The Japan Meteorological Agency (JMA) has issued an assessment regarding the eruption of Mount Anak Krakatau in Indonesia. Since Saturday, Anak Krakatau has been ejecting ash to a height of around 15 kilometres.

According to the JMA, the event will not currently cause a tsunami impact on Indonesia. This was based on an updated Weathernews report, as carried by The Nation.

“No significant sea level changes have been observed at monitoring stations in Japan or abroad,” the agency said, quoted on Monday (7/9/2026).

Japan had earlier begun examining the possibility of tsunami impacts following Friday’s eruption. The JMA initially announced monitoring efforts at 4am local time on Saturday.

The JMA took into account the unusual sea surface disturbances associated with the January 2022 Tonga eruption. However, a subsequent assessment ruled out any tsunami impact on Japan resulting from the latest Anak Krakatau eruption.

“Based on the agency’s assessment at the time, the earthquake was considered unlikely to cause a collapse large enough to trigger a tsunami. Nevertheless, officials will continue to monitor the volcano’s activity and any changes to its shape,” the site stated.

Previously, the Darwin Volcanic Ash Advisory Centre also identified ash reaching aviation level 500, equivalent to roughly 15.2 kilometres, over the weekend. Satellite observations showed the upper ash cloud moving westwards, whilst the lower layer drifted from south to south-east.

As of Sunday night, Anak Krakatau remained at Alert Level III. Residents, fishermen and visitors have been instructed to remain outside the three-kilometre danger zone.