FAULTING AND SEISMIC ZONES OF THE PHILIPPINES

GROUP 2

Active faults

Are structure along which we expect displacement to occur.

Inactive faults

Are structures that we can identify, but which do no have earthquakes.

Reactivated faults

Form when movement along formerly inactive faults can help to alleviate strain within the crust or upper mantle

Asperities.

The regions of higher friction along a fault plane, where it becomes locked, are called blank.

Fault Trace

Is the line on the Earth’s surface that marks where a fault plane intersects the ground.

Fault Scarp

Is a step or slope on the ground formed by vertical movement along a fault.

Heave

Is the horizontal component of slip along a fault, measured as the distance one block has moved sideways relative to the other.

Throw

Is the vertical component of slip along a fault, representing the difference in elevation between displaced rock layers.

Slip

Is the total displacement along a fault plane, representing the true movement of one block relative to another.

Central Philippine Fault Zone

Is responsible for the archipelago's fault creep, slow slide occurrences, and large earthquakes on the other end of the spectrum.

Marikina Valley Fault System

Is the most dangerous fault in the country. This is because it runs through the heart of Manila's most vibrant and busy neighborhoods.

Southern Mindanao Fault Lines

The Mindanao fault can be seen running through both the Celebes Sea and the Moro Gulf.

Western Philippine Fault Lines

If you weren't aware, the water level could also be a source of concern. The —- fault line runs through the seas of the Philippines' western region rather than on land.

Eastern Philippine Fault Lines

Was discovered beneath the ground in the same way that the Western Philippine Fault was. The Philippine Sea contains these active faults.

Seismic Zones

Is used to describe an area where earthquakes tend to focus.

Ground Rupture:

The direct tearing of the ground surface along a fault line, causing displacement, breaking roads, and tearing pipelines.

High earthquake risk:

Studies show where quakes are likely, how strong they’ll be, and what areas/infrastructure are most at risk.

Philippine Mobile Belt

The archipelago occupies the central portion.

Convergence of —- & —- has formed several active subduction zones marked by deep-sea trenches

Philippine Sea Plate and the Eurasian Plate

Philippine Trench

Earthquakes generated here often produce deep-focus seismic waves that travel long distances and provide insight into the Earth’s interior.

Manila Trench

Subduction of the Eurasian Plate (South China Sea Basin) beneath the Philippine Mobile Belt.

Cotabato Trench

Subduction of the Celebes Sea portion of the Eurasian Plate beneath the Philippine Mobile Belt.

Zone 2

Covers the provinces of Palawan (except Busuanga), Sulu, and Tawi-Tawi.

Seismic waves

Are vibrations that travel through the Earth's layers, carrying energy released during an earthquake.

P-waves (Primary)

The "first responders." They are longitudinal waves (compressional) that push and pull the ground.

S-waves (Secondary)

They move the ground up and down or sideto-side (transverse).

P-waves (Primary)

They are the fastest and can travel through both solids and liquids, which is how they pass through the Earth's liquid outer core.

S-waves (Secondary)

Unlike P-waves, they cannot travel through liquids; they only move through solids.

Love Waves

Move the ground in a horizontal, side-to-side motion. They are faster than Rayleigh waves.

Rayleigh Waves

Move in a rolling motion, similar to ocean waves. These are responsible for the most significant shaking and structural damage felt during an earthquake.

Marikina Fault

West Valley Fault System