Philippine Sea Plate Megathrust Activity Triggers M 7.7 Earthquake and Tsunami Threat

JAKARTA - The subduction activity of the Philippine Sea Plate megathrust triggered a tectonic earthquake with a magnitude of 7.7 that shook the southern coastal area of Mindanao, Philippines, on Monday, June 8 morning. The shallow earthquake was not only felt in the Philippines, but also triggered tsunami early warning in several eastern Indonesian regions.

Head of the Meteorology, Climatology, and Geophysics Agency (BMKG) Teuku Faisal Fathani explained that the earthquake occurred at 06.37 WIB with the epicenter at the coordinates of 5.80 degrees North Latitude and 125.14 degrees East Longitude, or about 244 kilometers northwest of Karatung Island, North Sulawesi, at a depth of 47 kilometers.

"This earthquake was triggered by the subduction activity of the Philippine Sea Plate," said Teuku Faisal in a press statement, Monday morning.

According to him, the position of the epicenter which is in the sea and the relatively shallow hypocenter depth indicate that the event is a tectonic earthquake due to plate subduction activity.

"The results of the source mechanism analysis show that the earthquake has a rising or thrust fault movement mechanism," he said.

BMKG explained that the characteristics of the rising fault that occurred in the subduction zone have the potential to trigger submarine deformation, thus posing a tsunami threat in a number of areas directly facing the earthquake source.

Although the epicenter was in the Philippines, the tremors were felt in various areas in eastern Indonesia. The highest intensity was recorded in Morotai, North Halmahera, with a scale of IV MMI.

Meanwhile, North Gorontalo Regency felt tremors on the scale of III-IV MMI. The tremor was also felt in Batudaa, Ternate, West Halmahera, Gorontalo, South Halmahera, East Halmahera, Parigi Moutong, Manado, Minahasa, Palu, Bitung, East Bolaang Mongondow, and Central Halmahera with an intensity of III MMI.

Until this report was submitted, BMKG had not received reports of any casualties or building damage due to the earthquake.

However, the results of the BMKG tsunami modeling show that the magnitude 7.7 earthquake has the potential to trigger tsunami waves in a number of regions in Indonesia.

The Alert Status is set for Minahasa, Bolaang Mongondow, Manado City, North Minahasa, South Minahasa, Buol, Sangihe Islands, Gorontalo, Talaud Islands, Minahasa Islands, Tolitoli, Palu City, Donggala, Ternate City, and Bitung City.

Meanwhile, the Alert status applies to Tidore City, Bulungan, Nunukan, Halmahera, Tarakan City, North Halmahera, East Kutai, Bontang City, and Berau Regency.

BMKG appeals to the public who are in the Alert status area to immediately move away from the coastal area and move to higher ground. Meanwhile, people in the Warning status area are asked to temporarily stop activities in coastal areas and river banks until the condition is declared safe.

In addition to issuing tsunami early warnings, BMKG also continues to monitor the development of seismic activity after the earthquake. Until 07.11 WIB, two aftershocks were recorded, with a magnitude of 6.7 and a magnitude of 5.9.

BMKG urges the public to remain calm, not easily provoked by unverified information, and to follow the development of official information through BMKG and local government communication channels.