A powerful 7.8 magnitude earthquake that struck off the southern Philippines on Monday has killed at least 47 people and injured 688, with 31 people still missing, according to government officials.

The offshore quake, one of the strongest to hit the Philippine archipelago in half a century, struck near the southern province of Sarangani and displaced more than 45,000 people. About half of those displaced remain in emergency shelters after the earthquake damaged more than 12,600 houses across farming towns and cities.

Sarangani province reported the highest death toll with 20 fatalities, mostly from a landslide that buried houses in the coastal town of Glan, according to the government's Office of Civil Defense. Glan Mayor Victor James Yap said 10 of his town's 31 villages remained inaccessible due to landslides, and he has requested government helicopters to deliver food and water to the isolated communities.

"We need food and water but it's difficult to transport them to some of our villages which remain isolated," Yap told DZMM radio network. "Choppers are needed to transport food because people there are already very hungry." The town of more than 100,000 people remains without power, and cellphone services are still disrupted.

Most earthquake deaths resulted from falling debris from collapsed buildings and landslides across Sarangani, General Santos city, and the provinces of South Cotabato and Davao Occidental. Two swimmers drowned and one remains missing off General Santos after being swept out to sea following the quake. The earthquake generated waves up to 1.4 meters above tide level in southern Philippines, with smaller waves reaching Indonesia, Palau, and southern Japan.

The earthquake ranks among the strongest to hit the Philippines since an 8.1 magnitude quake and tsunami killed approximately 8,000 people in August 1976. The Philippines experiences frequent seismic activity due to its location on the Pacific Ring of Fire, an arc of geological fault lines surrounding the Pacific Ocean.