Tsunami Risk Looms Over Yogyakarta Coast After Quake from Megathrust Zone

TEMPO.CO, Bandung - The 5.8-magnitude earthquake, later updated to 5.5-magnitude, that shook Yogyakarta and other areas on the southern coast of Java on Monday night, August 26, 2024, was caused by the activity of the subduction zone or megathrust zone. The epicenter was located in the Indian Ocean, 107 kilometers southwest of Gunungkidul.

“The earthquake occurred due to the collision between the Eurasian continental plate and the Indo-Australian Ocean plate, resulting in a thrust fault mechanism with a relatively west-east orientation,” explained Priatin Hadi Wijaya, Head of the Center for Volcanology and Geological Disaster Mitigation (PVMBG) of the Geological Agency, in his statement on Monday night, August 26.

The quake’s epicenter, which occurred at 19:57 western Indonesian time (WIB), was closer to Yogyakarta Province compared to other areas. Hadi cited the Meteorology, Climatology, and Geophysics Agency (BMKG) data that the strongest tremors were on the III-IV MMI scale, indicating that the earthquake was able to make walls and windows creak. Several houses and buildings in Gunungkidul, Bantul, and Sleman experienced cracks in the walls and damaged roofs.

“According to data from the Geological Agency, residential areas affected by the tremors are primarily located in the Disaster Prone Area (KRB) for medium to high earthquakes,” he said.

Tsunami Threat of Over 3 Meters

Hadi explained that the quake did not cause a tsunami despite its origin in the megathrust zone. This is allegedly because it did not trigger significant seabed deformation. However, he emphasized that the coastal area closest to the epicenter remained prone to tsunami disasters.

“According to the Geological Agency data,” Hadi reiterated, “the southern coastal areas of the Yogyakarta Province and Central Java are classified as tsunami-prone with the potential for high waves reaching over three meters.”

The Geological Agency urged the public to remain calm and alert to the possibility of aftershocks. Based on the BMKG data, there were 77 aftershocks from the M5.5 earthquake, with the strongest having a magnitude of 4.0 as of Tuesday morning.

“For residents whose homes were damaged, please evacuate to a safe place according to the instructions of local BPBD officers,” said Hadi.

The Geological Agency revealed that the earthquake in Yogyakarta was also recorded by the United States Geological Survey (USGS) and the GeoForschungsZentrum (GFZ) of Germany, with each releasing data on the M5.6 earthquake from a depth of 60.9 kilometers and M5.4 from a depth of 66 kilometers.

AHMAD FIKRI (CONTRIBUTOR)

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