Earth Science Activity
Finding Faults
INTRODUCTION:
The Philippine Fault Zone (PFZ) extends 1200 km across the Philippine
archipelago behind the convergent boundary of the Philippine Trench and the subduction
of the Philippine Sea Plate. This left-lateral strike-slip fault extends NW-SE (N30 – 40 W)
accommodating the lateral oblique motion of the subducting Philippine Sea Plate with
respect to the Philippine Trench. It extends from Davao Gulf in the south, bisects the
Caraga region at the Agusan River basin, crosses to Leyte and Masbate islands, and
traverses Quezon province in eastern Luzon before passing through Nueva Ecija up to the
Ilocos region in northwest Luzon. The northern and southern extensions of the PFZ are
characterized by branching faults due to brittle terminations. These horsetail faults are
indicative of the lateral propagation and further development of the PFZ. The fault's
current activity can be observed in Holocene sandstone outcrops on the Mati and Davao
Oriental islands. The fault experiences a slip rate of approximately 2-2.5 cm/year.
OBJECTIVE:
To locate some of the active faults in the Philippines.
MATERIALS:
Worksheet Access to the Internet
PROCEDURES:
1. Study the map of the distribution of Active Faults and Trenches in the Philippines.
2. Highlight the given fault systems in the map.
a. West Valley Fault – trace with orange color
b. Central Leyte Fault – trace with blue color
c. Central Mindanao Fault – trace with green color
3. Locate where you live on the map. Encircle the area and place a star symbol
yellow color.
4. Highlight with red color the name of the fault line nearest your location.
5. Connect to the internet and go to the fault finder application developed by
PHIVOLCS by logging in to Fault Finder (dost.gov.ph). Follow the instructions and
determine the distance of your house and school to the nearest active fault.
6. Visit the site https://hazardhunter.georisk.gov.ph/map to check the other hazards
that are near your location.
CN: 17 Score:
Name: Velasco, Brenard L. Date: October 17, 2023
Grade & Section: 8-Counsel
Earth Science Activity
Finding Faults
Iba ba
Observations:
1. What is the nearest active fault system from your place?
Iba fault
2. After studying the distribution of fault systems in the map,
what islands are the safest from strong tectonic earthquakes?
Palawan is an example of a safe island, because it is the safest
place in the Philippines. Palawan has no fault lines so it will not
be affected. Palawan is considered a safe destination, because it is
safe from natural disasters typhoons or other calamities like fire,
earthquakes and volcanic eruptions.
3. Based on the site https://hazardhunter.georisk.gov.ph/map,
what are the other hazards that are near your location
flooding, storm surge, landslide and the after effects of
earthquake Seismic waves of an Earthquake Hydro-
meteorological hazard of atmospheric, hydrological. One
example is tropical clones or typhoon and hurricanes. Floods,
Rain-induced landslide and storme surge is included here.
The distance between my home from the nearest fault here which is Iba Fault is approximately
6.7 km
Fault systems given:
West Illocos Fault System
Dummon River Fault System
Valley Fault System
Lanao Fault System
Zamboanga Fault System
