Powerful Earthquake Rocks Philippines On National Holiday
October 15, 2013

Powerful Earthquake Rocks Philippines On National Holiday

Lawrence LeBlond for redOrbit.com - Your Universe Online

A powerful 7.1-magnitude earthquake rocked the Philippines Tuesday morning, killing at least 85 people and injuring hundreds more.

The temblor occurred on October 15 at about 8:12 a.m. (local time) and, according to Renato Solidum of the Philippine Institute of Volcanology and Seismology, it was centered about 32 miles underground near the small town of Carmen.

However, a report by the US Geological Survey (USGS) said the quake occurred near the Philippine town of Catigbian, on the central island of Bohol, at about 12 miles deep.

The Philippines News Agency reported that droves of people ran into the streets panicking as the ground shook buildings, crumbling them to the ground. It said that most people were killed by falling rubble and debris.

The earthquake caused extensive damage, which was evident around the densely populated Cebu city, which sits across a narrow strait from Bohol, causing deaths there when one building in the port, as well as the roof of a market area, collapsed.

The quake also triggered a stampede of people who were gathered inside a gym in Cebu city. The mad exodus of panicking people resulted in at least five people being crushed to death, while eight others were seriously injured, Neil Sanchez, provincial disaster management officer, said in a statement.

Vilma Yorong, a provincial government employee in Bohol, said people ran from their offices and “hugged trees outside because the tremors were so strong.”

"When the shaking stopped, I ran to the street and there I saw several injured people. Some were saying their church has collapsed," she said in phone interview with The Associated Press. Once the tremors stopped, she said fear set in that it may trigger a deadly tsunami and many ran up the mountainside.

But because the quake was centered inland there would be no tsunami, according to the Pacific Tsunami Warning Center. However, it noted that earthquakes this large can sometimes cause tsunamis within 61 miles of the epicenter.

Tuesday was a national holiday for the country – the Muslim festival of Eid al-Adha – which may have saved many lives as most people were home when the temblor occurred. Also, the quake was much deeper below the surface than the central Philippine 6.9-magnitude temblor that killed 100 people last year.

Cebu city, about 350 miles south of Manila, has a population of more than 2.6 million people. Cebu is the second largest city in the Philippines. Nearby Bohol has 1.2 million and is a popular tourist destination because of its beach and island resorts.

The quake reportedly damaged many roads and bridges, as well as historic buildings, including churches dating back to the Spanish colonial period. Among them is the country’s oldest, the 16th-century Basilica of the Holy Child in Cebu, which lost its bell tower during the quake, the AP reported.

After Tuesday’s temblor, officials warned residents not to enter major buildings until their structural integrity could be verified. They also warned of the potential for dangerous landslides as aftershocks continued to shake the region.

President Benigno S. Aquino plans to visit the affected region on Wednesday, according to a government spokesman. Both the islands of Bohol and Cebu have been declared to be in a state of calamity by the government, which authorizes additional assistance to the affected areas.

Regional military commander Lt. Gen. Roy Deveraturda said he recalled soldiers from the holiday furlough to respond to the disaster. He said a pier was damaged in Bohu’s capital city Tagbilaran and some other damage was seen at Cebu’s international airport, but navy ships and air force planes could use alternative ports to bring assistance to the region.

Later Tuesday, after officials checked runways and buildings for damages, passenger flights resumed.

The USGS said on its Earthquake Hazards Program site that Tuesday’s earthquake “occurred as the result of shallow reverse faulting on a moderately inclined fault dipping either to the northwest, or to the southeast. The depth of the event indicates it ruptured a fault within the crust of the Sunda plate, rather than on the deeper subduction zone plate boundary interface.”

“At the latitude of this earthquake, the Philippine Sea plate moves towards the west-northwest with respect to the Sunda plate at a rate of approximately 10 cm/yr, subducting beneath the Philippine Islands several hundred kilometers to the east of the October 15 earthquake at the Philippine Trench,” it continued.

“The Philippine Islands straddle a region of complex tectonics at the intersection of three major tectonic plates (the Philippine Sea, Sunda and Eurasia plates),” the USGS noted.

The region has experienced no less than 19 events of magnitude 6 or greater within 300 miles of Tuesday’s quake. Nearly a dozen of these such events have been relatively shallow (less than 42 miles deep). One of these quakes, a 6.8-magnitude temblor, occurred on February 8, 1990, damaging more than 3,000 homes and causing several fatalities, according to the USGS.