Traces of giant tsunami discovered in South Java, risk of recurrence

The Indonesian National Research and Innovation Agency (BRIN) has just announced traces of an ancient tsunami on the southern coast of Java Island, including the Pangandaran area, West Java.

According to BRIN, this tsunami was caused by a magnitude 9 earthquake and is likely to recur in the future.

In a statement on August 17, BRIN said sediment layers dating back about 1,800 years were found in Lebak, Pangandaran and Kulon Progo, showing that the South Java area had suffered a giant tsunami.

BRIN's study, which spanned from 2006 to May 2025, also found that the phenomenon repeats itself in cycles of 600-800 years, with traces of it occurring 3,000, 1,000 and 400 years ago.

According to Purna Sulastya Putra, a researcher at the Research Center for Geohazards (PRKG) under BRIN, the results are a clear warning of the risk of a major tsunami in South Java. He said the evidence was collected through field surveys in swamps and lagoons, combined with microbiological, chemical and radiocarbon dating analyses.

BRIN emphasizes that in the context of rapid development of strategic infrastructure in South Java, ancient tsunami data should be integrated into spatial planning and disaster risk reduction plans. This information will help identify vulnerable areas, establish evacuation sites and rescue routes.

Mr Purna urged people to be vigilant: "If you feel a major earthquake near the coast, immediately move to higher ground." He stressed that tsunamis cannot be prevented, but loss of life and property can be minimized through knowledge and preparation.