TEMPO.CO, Jakarta - Exactly 20 years ago on July 17, 2006, a tsunami struck the coast of Pangandaran and its surrounding areas following a magnitude-7.7 earthquake centered in the southern waters of West Java. Such a tsunami-generating earthquake has the potential to recur, though the exact timing remains impossible to predict.
"Prior to 2006, a tsunami earthquake hit south of Pangandaran in 1921," Eko Yulianto, a paleotsunami research expert from the National Research and Innovation Agency (BRIN), told Tempo on Friday, July 17, 2026.
Eko noted that hypothetical calculations by fellow researchers estimate the recurrence interval of a megathrust earthquake with a magnitude of 9.0 or greater along Java's southern coast at roughly 675 years. However, smaller tsunamigenic earthquakes may occur much more frequently.
"Occurrences of minor earthquakes triggering tsunamis in southern Java were recorded at least in 1840 and 1859 in southern Yogyakarta and Pacitan, and later in 1994 in Banyuwangi."
Pepen Supendi, a seismologist from the Meteorology, Climatology, and Geophysics Agency (BMKG), stated that the Pangandaran disaster is considered the largest tsunami to hit Java since the 1994 Banyuwangi event. The tsunami waves rolled in about an hour after the initial quake, hitting the coast between 4:15 and 4:30 p.m. WIB with an average height of 5 to 10 meters.
In addition to Pangandaran, the tsunami also battered a 250-kilometer stretch of coastline extending from Cilacap to the south of Yogyakarta. "Tsunami waves continued to propagate across the Indian Ocean toward Africa for hours," he noted during a webinar commemorating the 20th anniversary of the Pangandaran tsunami on Thursday, July 16, 2026.
Pepen explained that during the Pangandaran earthquake-tsunami, the rupture of the earth's crust was remarkably slow, lasting three minutes at a shallow depth. This mechanism meant the ground shaking felt relatively weak and non-dominant. Nonetheless, the length of the crustal rupture reached 200 kilometers.
"Why did it trigger such a massive tsunami in Pangandaran? Because the earthquake's epicenter was located near the trench, which efficiently displaced the ocean floor upward," Pepen said.
According to data from the Pangandaran Regional Disaster Management Agency (BPBD), the 2006 catastrophe left 405 people dead, 27 missing, 274 injured, and forced 13,198 residents to evacuate.
Preparedness for Recurring Tsunamis
The Head of the Pangandaran BPBD, Dodo Kusnadi, mentioned that two areas are currently designated and prepared for potential future tsunamis: Pangandaran Village and Batu Karas. He acknowledged that evacuation signage remains inconsistent, with some routes pointing directly toward local hotels. "As it turns out, the high-rise hotels in Pangandaran are fully prepared to serve as vertical evacuation centers, specifically to ensure the safety of tourists," he explained.
Furthermore, Dodo noted that the closest safe zone to the shoreline is the local nature reserve. This site had previously served as a vital sanctuary during the 2006 disaster. "The nature reserve is the safest and closest place from the beach."
BMKG Deputy of Geophysics Nelly Florida Riama reminded the public that tsunamis are rare disasters, meaning community awareness tends to erode over time. Therefore, the 20th anniversary of the Pangandaran tsunami should serve as a vital opportunity to preserve collective memory and bolster resilience against future coastal hazards.
"Preparedness can only be achieved if awareness remains alive," she said, adding, "This commemoration is not just about remembering a tragedy, but ensuring that the painful lessons of the past protect our descendants."
Read: Java Hit by Two Megathrust Quakes Since 1994; UGM Expert Explains
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