Philippines Earthquake Raises Mindanao Seabed by Two Metres and Kills 61
The Philippines earthquake struck southern Mindanao island on Monday with a magnitude of 7.8 and killed at least 61 people while leaving 40 missing according to updated disaster agency tolls. [1] This event also produced coastal uplift that raised the seabed by as much as two metres and triggered a marine die-off along newly exposed shorelines. [1]
Overview of the Magnitude 7.8 Earthquake
The 7.8-magnitude tremor in southern Mindanao island on Monday has also left at least 40 people missing according to updated tolls from the disaster agency. [1] Local residents first reported the geological phenomenon known as coastal uplift two days after the quake. [1] The Philippines earthquake produced immediate human impacts that included the confirmed deaths and the ongoing count of missing individuals. [1] Disaster agency figures place the fatalities at a minimum of 61 while search operations continue amid the reported missing persons. [1] The main tremor set off a sequence of effects that extended beyond the initial shaking to include visible changes along the coastline. [1]
Coastal Uplift and Seabed Displacement
A shifting of the Cotabato Trench pushed upward part of the coastlines of Sarangani and Davao Occidental provinces and exposed the bottom of the sea that was originally submerged. [1] Approximately two metres was the mapped uplift according to the Philippine Institute of Volcanology and Seismology. [1] The quake raised the seabed by as much as two metres and extended the shoreline by as much as 200 metres in some places. [1] This displacement occurred when the Cotabato Trench experienced a shift that lifted previously submerged areas into view. [1] The measured rise reached up to two metres in locations where the seabed became newly exposed land. [1]
Philippines earthquake raised Mindanao seabed by up to two metres, killing 61 people. — Source: gdelt
Environmental Impact on Marine Life
The powerful earthquake raised the seabed by as much as two metres and exposed coral while harming marine life according to the environment department. [1] The rise in the seabed left coral reefs above water and contributed directly to a marine die-off in the affected zones. [1] Shoreline extension of up to 200 metres in places left sections of the sea bottom that was originally submerged now open to air and sunlight. [1] The environmental department noted that the uplift phenomenon harmed marine life by removing the protective cover of seawater from coral and other organisms. [1] Residents observed the changes two days after the main tremor when the newly raised seabed became visible along the coast. [1]
Seismic Context of the Cotabato Trench
The Cotabato Trench lies as close as 50 kilometres off the coast of southern Mindanao and is the site of frequent seismic activity. [1] This trench produced the shift responsible for the coastal uplift during the Philippines earthquake. [1] A swarm of thousands of mostly small earthquakes was recorded in January at the same trench location. [1] The trench’s proximity to the coast allowed the upward push to affect populated provinces directly. [1] Frequent seismic events at the Cotabato Trench have included both the recent major tremor and earlier swarms of smaller quakes. [1]
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Recent Aftershocks in the Philippines
A magnitude 5.1 earthquake occurred at a depth of 10.0 km and was located 27 km SE of Magdalena, Philippines. [3] Another event registered magnitude 5.2 at a depth of 35.0 km and was positioned 53 km ENE of Hinatuan, Philippines. [4] A magnitude 4.6 earthquake took place at a depth of 54.4 km and was recorded 66 km S of Sarangani, Philippines. [5] These aftershocks were documented by the USGS near locations that include Magdalena, Hinatuan, and Sarangani. [3][4][5] The sequence of events followed the main 7.8-magnitude tremor and contributed to ongoing seismic monitoring in the region. [1]
Ongoing Response and Damage
A man stands on a blocked road after a major landslide triggered by an earthquake in Sarangani Province on Thursday. [1] Landslides and blocked roads have been reported as part of the damage from the Philippines earthquake. [1] Search efforts continue for the 40 people listed as missing in the updated disaster agency tolls. [1] The environment department issued statements on Sunday describing the coastal uplift and its effects on marine life. [1] Access to some areas remains limited due to the landslides and road blockages that followed the main tremor. [1]
What to watch next includes continued monitoring of aftershocks near Magdalena, Hinatuan, and Sarangani as well as further assessments of the exposed seabed and its impact on marine life.
