Very strong M7.1 earthquake hits near the coast of Mindanao, small tsunami observed, Philippines

A strong and shallow earthquake registered by the USGS as M7.1 hit near the coast of Mindanao, Philippines at 17:46 UTC on August 11, 2021. The agency is reporting a depth of 65.6 km (40.7 miles). EMSC is reporting M7.1 at a depth of 58 km (36 miles). GFZ M7.0 at a depth of 10 km (6.2 miles).

The epicenter was located 66 km (41 miles) SE ob Bobon (population 4 515) and 82 km (51 miles) SE of Mati (population 105 908), Davao, Philippines.

There are about 480 000 people living within 100 km (62 miles).

12 000 people are estimated to have felt very strong shaking, 685 000 strong, and 5 763 000 moderate.

Based on the preliminary earthquake parameters, hazardous tsunami waves are possible for coasts located within 300 km (186 miles) of the earthquake epicenter — along the coast of the Philippines and Indonesia, PTWC said.

A tsunami is a series of waves with time between wave crests from 5 minutes to an hour. The hazard may persist for many hours or longer after the initial wave.

Impacts can vary significantly from one section of coast to the next due to local bathymetry and the shape and elevation of the shoreline. They can also vary depending upon the state of the tide at the time of the maximum tsunami waves.

Persons caught in the water of a tsunami may drown, be crushed by debris in the water, or be swept out to sea.

The tsunami threat from this earthquake has now passed, PTWC said at 19:42 UTC.

Image credit: TW/SAM, Google

 

The USGS issued a Green alert for shaking-related fatalities and economic losses. There is a low likelihood of casualties and damage.

Overall, the population in this region resides in structures that are a mix of vulnerable and earthquake-resistant construction. The predominant vulnerable building types are unknown/miscellaneous types and heavy wood frame construction.

Recent earthquakes in this area have caused secondary hazards such as tsunamis and landslides that might have contributed to losses.

Estimated population exposure to earthquake shaking

Selected cities exposed

Regional seismicity

Featured image credit: TW/SAM, Google