Bohol quake can kill over 50,000 in Metro Manila - study

MANILA, Philippines - What could happen if the magnitude-7.2 earthquake that struck Bohol province on Tuesday hits a highly urbanized area like the National Capital Region?

According to the 2004 Metro Manila Earthquake Impact Reduction Study (MMEIRS), a magnitude 7.2 earthquake will devastate the entire metropolis, killing more than 50,000 people while destroying infrastructures, damaging power and water sources, and causing fire outbreaks.

The study, which was conducted by the Japan International Cooperation Agency, showed 18 scenario earthquakes in Metro Manila to enable the government to anticipate the damages and lay out an impact mitigation and reduction plan.

The MMEIRS revealed that due to a potential magnitude 7.2 earthquake generated by the West Valley Fault, at least 40 percent of the total number of residential buildings within Metro Manila will be affected. About 170,000 houses will collapse while 340,000 more will be partly damaged.

This building collapse will directly affect large numbers of people, the MMEIRS said, since it is estimated to cause 34,000 deaths and 114,000 injuries. Additional 18,000 fatalities are expected due to the fire spreading after the major earthquake.

"This human loss, together with properties and economy losses of Metropolitan Manila will be a national crisis," the MMEIRS summary said.

Intensity VIII and IX will be felt alongside Markinia River and Manila Bay and the tremor will damage nine bridges and 1,100 medium and high-rise buildings in the metro. Other pertinent structures will also be heavily damaged, including 115 schools, 14 hospitals, and 16 fire and police stations.

The MMEIRS said the powerful earthquake will also result in several fire outbreaks and cut 30 kilometers of power lines and 95 kilometers of telephone cables, and damage 4,000 points of water supply.

Metro Manila divided

The 2004 study said Metro Manila will possibly be separated into four regions by the impact of a magnitude 7.2 earthquake.

The western part of Metro Manila will be isolated from other parts of the region due to fires and building collapse.

In the the eastern part of the metro, all road networks running east to west will be broken due to the fault movement. Other roads from north to south in fault areas will be difficult to use due to the high number of collapsed buildings.

Geographical and building collapse will also separate the northern and southern parts of Metro Manila. The MMEIRS said the intersecting areas between Manadaluyong and Makati has a high possibility of building collapse.

The MMEIRS also showed that several areas possess urban vulnerabilities against earthquake damage such as difficulties in evacuation, flammability and building collapse.

Magnitude-7.2 quake in NCR soon?

The MMEIRS does not predict when the "Big One" will hit Metro Manila as it only shows the potential effects of major earthquakes so the government and the public may prepare.

However, it noted that an earthquake generated by the West Valley Fault, which is considered to potentially cause the largest impact to Metro Manila, is "approaching."

The study said the West Valley Fault has moved four times and generated strong earthquakes within the last 1400 years. The approximate return period of these tremors is less than 500 years and no event along the fault line is known after the 1600s.

"It means that the active phases of the Valley Fault is approaching. Many research studies indicate that the estimated magnitude will be around 7 or more," the MMEIRS said.

The study recommends that in order to manage the potential earthquake disaster in Metro Manila, an earthquake disaster mitigation plan should be prepared and actions must be started as soon as possible.

The disaster management plan will focus on raising awareness of concerned organizations, employ a comprehensive disaster management approach, and strengthen coordination between the central government to local governments and communities.