A disaster waiting to happen: West Valley Fault quake MANILA - As if typhoons and floods were not enough, Metro Manila must also prepare for a strong earthquake that's long overdue. "It might happen in our lifetime, it might take longer. But the more prudent thing to do is prepare," says Philippine Institute of Volcanology and Seismology (Phivolcs) Director Renato Solidum. The latest estimate of Phivolcs, in partnership with Geosciences Australia under the Risk Analysis Project (RAP), shows Quezon City and Manila will have the highest number of casualties should a magnitude 7.2 quake emanate from the West Valley Fault. The RAP validates and updates findings of the Metro Manila Earthquake Impact Reduction Study (MMEIRS) undertaken by Japan International Cooperation Agency (JICA), Metropolitan Manila Development Authority (MMDA) and Phivolcs 10 years ago. It says 5,524 people could die in Quezon City alone, and 23,103 people could be seriously injured. "The number of people who will die is dependent on the number of buildings that will collapse," says Solidum. In Manila, the figures are slightly lower but no less disturbing: 5,449 people could die and 21,620 could be seriously injured. The 90-kilometer West Valley Fault runs from the Angat reservoir in Bulacan through Quezon City, Marikina, Pasig, Makati, Taguig, Muntinlupa, Rodriguez Rizal, Cavite and ends in Calamba, Laguna. It has moved four times in the last 1,400 years. The last time it ruptured was about 356 years ago. "It doesn't mean the next one will be 7.2, but it's capable of generating a 7.2 quake," Solidum says. SIX TIMES MORE FATALITIES THAN YOLANDA In all, as many as 37,000 fatalities in Metro Manila and Rizal are projected--that's nearly six times more than the official death toll from Supertyphoon Yolanda. Serious injuries are expected to run up to 148,000. "140,000 injured people cannot be accommodated in Metro Manila's hospitals. So what do you do? Construct a lot of hospitals, or make sure houses and buildings are safer so they will not collapse?" Solidum asks. "The main solution is not merely being ready to respond, but making sure houses and buildings that can collapse are corrected while there's time." Read more... http://www.abs-cbnnews.com/focus/07/17/14/disaster-waiting-happen-west-valley-fault-quake
It comes from Philvolcs. They called the Mount Pinatubo eruption correctly. Therefore not sensational journalism, but a good call. When I lived in Manila, rumour had it that the only building that would withstand a serious earthquake was the Shangri-La Hotel.
Useful for working out if your house will be okay.... http://tulisanes.wordpress.com/2012/04/03/is-your-house-standing-on-an-earthquake-faultline/
It will happen, I hope not soon, they won't have fixed the housing and the results will be far worse than predicted here, and the quake could well be much larger than 7.2
Presumably from the moans and groans and various emissions before the occurence? On that basis it may well be somewhat easier to recognise an impending eruption than it is an impending earthquake. In many senses the West Valley Fault is already "cocked" or charged up with energy, ready to go at anytime on a "straw that breaks the camels back" basis. Just an extra few foot pounds of force needed to overcome the friction just about keeping it from activating, as we speak.
Yep doesn't make me feel any better about it, we're about 4 miles from the west valley fault, the problem is that due to the narrow geography of Metro Manila so many are about 4 miles or less from the fault. John do you know if it is a slip type fault or would there be an upthrust on the west or east side of it, if the west side suffered a significant downward movement the bay could flood vast area's including where we live
I would have to research it and work it out. The main sources of tectonic compression are from (roughly) east and west. So this fault is an expression of those forces.
I am seeing it described as a dextral strike slip fault. As in the video. So then this appears to be the nature of the fault. The one in the video is sinistral (left oriented) To the onlooker a dextral strike slip fault is one where the land on the other side of the fault moves to that persons right. So no or little vertical movement, it would suggest. And east of the West Valley Fault will be heading south relative to the west side. Looking at the faultline it is an expression of the tectonic forces coming in from east and west but the whole thing is a vector and the forces arent exactly directly opposite one another. Jusyt approximately so. So there will be some movement in other directions. The whole of the PMB is one big mashup and geologists talk about (euler) rotations which I take to mean that the Philippines is being coerced rotationally. Palawan itself is poking itself into west side of the rest of the Philippines adding to the mayhem.
The Marikina or West Valley Fault is described as a locked fault. This means that it quietely absorbs stress until such time that the stress overcomes the friction locking the stress in place. Then comes the earthquake.
The only thing is that there evidently has been some vertical displacement across the fault in the past. You would be able to see that I gather? But Philippine geologists still describe it as a strike slip fault. But not sure why. Maybe it has been seen to slip horizontally in the more recent past quake episodes.
Yes, unfortunately we are talking about plate movement at the rate that our finger nails grow at, spread out over 400 years. All that energy is being pent up and stored and will undoubtedly be released at some time in the not so distant future. There is nothing that can be done to stop it. The best approach is to avoid it. And / or limit the damage.
