A magnitude 7.2 earthquake is used in PHIVOLCS’ West Valley Fault earthquake scenario for Metro Manila. It is a planning scenario, not a prediction of when the fault will rupture or of the exact magnitude of a future event. So what does magnitude 7.2 mean, and how could the shaking affect different places?
Magnitude measures an earthquake’s overall size, while intensity describes the shaking experienced at a particular location. Energy comparisons are not a reliable guide to local damage; the safety of buildings and ground conditions matter greatly.
A magnitude 7.2 earthquake on the West Valley Fault could cause destructive shaking across Metro Manila and surrounding areas. Shaking intensity and damage will not be uniform: they depend on distance from the rupture, geology and building construction.
How Strong Again?
Some of us might be used to feeling earthquakes that sway us from side to side. In fact, unless you have experienced the 1990 earthquake that rocked North Luzon and toppled the Hyatt Terraces Hotel, that may be the only movement you may think of in an event of an earthquake.
The cities listed below may experience strong shaking in the West Valley Fault scenario, but the list does not mean that every location will experience the same direction or intensity of ground motion.
| Caloocan | Paranaque |
| Las Pinas | Pasay |
| Malabon | Pasig |
| Makati | Pateros |
| Mandaluyong | Quezon City |
| Manila | San Juan |
| Marikina | Taguig |
| Muntinlupa | Valenzuela |
| Navotas |
Strong earthquakes can produce horizontal and vertical movement, but the precise motion experienced varies by place. It is unsafe to assume that all cities will shake in exactly the same way.
And then you start to imagine that movie from 2012…
“…why did I ever watch that movie?”
An earthquake has one magnitude but different shaking intensities at different places. Distance from the rupture, local soil and rock conditions, and the characteristics of each building all affect the hazard. See the USGS explanation of magnitude and intensity.
What then…
Strong shaking can move unsecured objects and damage vulnerable structures, so secure tall furniture, appliances, shelves and anything that could fall. Check your surroundings for hazards and prepare a family emergency plan. Magnitude alone cannot tell you what a particular home or building will experience.
Start with the things that can injure you inside the home: tall furniture, large decorative objects, unsecured shelves, appliances and unsupported masonry. Then review the practical supplies your household would need if power, water or communications were disrupted. WVF’s Emergency Preparedness Essentials organizes those needs by category.
The most important next step is to turn awareness into a household plan: decide how your family will communicate, where you will meet, who can pick up children, what medicines and records must be accessible, and what you will do if home is temporarily unusable.
TURN EARTHQUAKE AWARENESS INTO A FAMILY PLAN
Know the hazard. Then decide what your family will do.
The WVF Family Emergency Planner helps households organize emergency contacts, meeting points, child pickup arrangements, evacuation details, medications and essential records before a major earthquake disrupts normal routines.
Prefer to start free? Use the WVF Earthquake Preparedness Quick Start Guide.
Note: A quake just occurred while finishing this article. We posted a breaking news about it here – Breaking.
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