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Are you Earthquake Safe? Metro Manila, Laguna, Batangas, Cavite, Bulacan and Rizal are prone to Earthquake Damage!
Earthquake

When it comes to Earthquake, 2 important factors are considered to know the extent of probable damage. These are Earthquake "MAGNITUDE" and Earthquake "INTENSITY".

 

Magnitude is the strength of the Earthquake using the Richter Scale. Intensity is how you or your structure feels the strength of this Earthquake depending on your location and the soil conditions of your area.

 

To know the Earthquake Risk on your structure, we look at the Earthquake Intensity it may feel at a probable Magnitude. Below is the Intensity Map or Earthquake Risk Map from PHIVOLCS based on the most probable Magnitude 7.2 Earthquake that will hit Metro Manila.

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From the Intensity Earthquake Risk Map above, it is shown that Metro Manila will likely suffer an Intensity 8 (Low 8 to High 8) to Intensity 9 (Low 9) or a Very Destructive Earthquake to a Devastating Earthquake according to PEIS or PHIVOLCS Earthquake Intensity Scale.

PEIS or PHIVOLCS Earthquake Intensity Scale is shown below:

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Intensity 8 and 9 Earthquakes cause heavy damage even on well built buildings. For your structure to be Earthquake safe, the following factors have to be STRONGLY CONSIDERED.

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1.) DISTANCE FROM FAULT LINE

Check out the Fault Line below and estimate your distance from the fault line. If your property is less than 10 kilometers from the Fault line, you have a higher Earthquake / Seismic Damage Risk.

Eartquake Map

The above MAP is for the Valley Fault System in Metro Manila, Laguna, Batangas, Cavite, Bulacan and Rizal Only (Updated May 2015)

Below is the updated 2015 Active Faults and Trenches from PHIVOLCS:

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Buildings less than 10 kilometers from the Fault are vulnerable to Earthquake Damage according to the National Structural Code 2015.

Contact us for a structural assessment and a structural retrofit design (structural strengthening of existing structure) could be needed for your structure.

2.) SOIL PROPERTIES

2a.) Soil Stiffness
The Metro Manila Map below is the approximate Soil Stiffness and Profile (After Saldivar Sali, 1992). Please take note that this is a generalization only. We cannot guarantee accuaracy on your lot.

NSCP (National Structural Code of the Philippines 2015) 208.4.3.1 Soil Profile Type and under Table 208-2 Soil Profile Types below:

 Sa = Hard Rock

 Sb = Rock

 Sc = Very Dense Soil and Soft Rock

 Sd = Stiff Soil

 Se = Soft Soil

2b.) Soil Liquefaction Hazard

 

Liquefaction (soil liquefaction in particular) is defined in wikipedia as:

"Soil liquefaction describes a phenomenon where by a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid."

Liquefaction Hazard Map of Metro Manila (2001). Source: PHIVOLCS

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3.) DESIGN AND CONSTRUCTED BY A LICENSED PROFESSIONAL

Below is a sample of the structural modeling including Earthquake / Seismic Analysis:

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4.) BUILDING / STRUCTURE DESIGNED AND CONSTRUCTED USING UPDATED 2015 NSCP (National Structural Code of The Philippines)

- The Structural Code has been updated in 1992, 2001, 2010 and most recently last 2015. Structures built and designed before 1992 are prone to Earthquake Damage as the structural design may not resist Earthquake forces. Structures designed and constructed using the 2015 National Structural Code can safely resist a magnitude 8 to 9 Earthquake.

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