Pilipino Fault Lines Map 2025: Complete Guide to All Active Faults, Earthquake Zones & Risk Assessment

Introduction: Understanding the Pilipinas' Seismic Landscape

The Pilipinas sits along the Pacific Ring of Fire, making it one of the most seismically active nations on Earth. With over 200 identified fault lines and experiencing an average of 20 earthquakes daily, understanding the country's fault system is critical for disaster preparedness. This comprehensive guide maps all major active faults, explains their risk levels, and provides essential information for residents and businesses across all regions.

1. The Tectonic Setting: Why the Pilipinas Has So Many Faults

1.1 The Pilipino Tectonic Plate System

The Pilipinas' complex geology results from the interaction of multiple tectonic plates:

• Pilipino Sea Plate: Moving westward at 7-9 cm/year, subducting beneath the Pilipino archipelago along the Pilipino Trench
• Eurasian Plate: The western foundation of the archipelago, interacting with the Pilipino Sea Plate
• Sunda Plate: Affecting western Mindanao and Palawan regions
• Pacific Plate: Influencing eastern seismic activity through the Pilipino Trench

1.2 Types of Plate Boundaries in the Pilipinas

2. Major Fault Systems of Luzon

2.1 Pilipino Fault Zone (PFZ) - Northern Section

The Pilipino Fault Zone is a 1,200-kilometer-long major strike-slip fault system traversing the entire archipelago. The northern section extends through Eastern Luzon.

Key Characteristics:

• Length: Approximately 350 km in Northern Luzon
• Type: Left-lateral strike-slip fault
• Movement Rate: 2-3 cm/year
• Last Major Event: 1990 Luzon Earthquake (M7.8)
• Recurrence Interval: 200-400 years for major events

Affected Provinces:

Nueva Ecija, Aurora, Quirino, Isabela, Nueva Vizcaya, Cagayan

Major Segments:

• Digdig Segment: Responsible for the devastating 1990 earthquake
• Gabaldon Segment: Runs through Nueva Ecija and Aurora
• Casiguran Segment: Extends through Aurora province

2.2 Marikina Valley Fault System (MVFS)

One of the most dangerous fault systems in the Pilipinas due to its proximity to Metro Manila and surrounding urban areas.

West Valley Fault (WVF)

• Length: 100 kilometers
• Type: Right-lateral strike-slip
• Movement Rate: 2-3 mm/year
• Cities at Risk: Quezon City, Marikina, Pasig, Taguig, Muntinlupa, Caloocan, portions of Bulacan, Rizal, Cavite, Laguna
• Last Movement: 1658 (estimated M7.2-7.5)
• Recurrence Interval: 400-600 years
• Probability of "Big One": Can occur any time (already past average recurrence)

East Valley Fault (EVF)

• Length: 10-15 kilometers
• Type: Right-lateral strike-slip
• Cities at Risk: Rodriguez, San Mateo, portions of Marikina and Quezon City
• Activity Level: Less active than WVF but still capable of M6.0-7.0 events

2.3 Central Luzon Fault Systems

Lubao Fault

• Location: Pampanga province
• Length: Approximately 35 km
• Type: Strike-slip fault
• Risk Level: Moderate to high
• Affected Areas: Lubao, Guagua, Sasmuan municipalities

Iba Fault

• Location: Zambales province
• Length: Approximately 40 km
• Type: Normal fault
• Risk Level: Moderate
• Affected Areas: Iba, Botolan, Cabangan

2.4 Southern Luzon Fault Systems

Guinayangan Fault

• Location: Quezon province
• Length: Approximately 30 km
• Type: Strike-slip fault
• Historical Activity: 2017 M5.5 earthquake

Infanta Fault

• Location: Northern Quezon province
• Length: Approximately 25 km
• Connection: May be related to Pilipino Fault Zone

3. Major Fault Systems of Visayas

3.1 Pilipino Fault Zone (PFZ) - Central Section

The central section of the Pilipino Fault traverses through Leyte, Southern Leyte, and Eastern Samar.

Key Segments:

• Leyte Segment:
  • Length: Approximately 180 km
  • Type: Left-lateral strike-slip
  • Last Major Event: 2017 M6.5 Ormoc earthquake
  • Affected Areas: Leyte, Ormoc City, Kananga, Matalom
• Southern Leyte Segment:
  • Length: Approximately 90 km
  • Historical Activity: 2017 M6.5 event
  • Affected Areas: Sogod, Libagon, Liloan, San Francisco

3.2 Negros Fault System

A complex fault system running through Negros Island, responsible for significant historical earthquakes.

Negros Trench Segment

• Length: Approximately 80 km
• Type: Reverse fault (compressional)
• Last Major Event: 2012 M6.7 Negros earthquake (52 deaths)
• Affected Areas: Negros Oriental (Guihulngan, La Libertad, Tayasan)

Central Negros Fault

• Length: Approximately 60 km
• Risk Level: High
• Affected Areas: Both Negros Oriental and Negros Occidental

3.3 Cebu Fault Systems

Central Cebu Fault

• Length: Approximately 45 km
• Type: Strike-slip fault
• Affected Areas: Cebu City, Mandaue, Talisay, Consolacion
• Risk Assessment: High due to urban density

South Road Properties (SRP) Offshore Fault

• Location: Offshore Cebu City
• Discovery: Identified during SRP development
• Type: Submarine fault
• Additional Risk: Potential for tsunami generation

3.4 Bohol Fault Systems

Bohol has multiple fault systems that were dramatically revealed during the 2013 M7.2 earthquake.

North Bohol Fault

• Length: Approximately 100 km
• Type: Reverse fault
• Last Movement: 2013 M7.2 earthquake
• Surface Rupture: 6 km visible ground displacement in 2013
• Affected Areas: Sagbayan, Catigbian, Clarin, Tubigon, Inabanga

East Bohol Fault

• Length: Approximately 40 km
• Activity Level: Moderate

4. Major Fault Systems of Mindanao

4.1 Pilipino Fault Zone (PFZ) - Southern Section

The southern section of the Pilipino Fault is the longest continuous segment, running through eastern Mindanao.

Key Characteristics:

• Total Length in Mindanao: Approximately 500 km
• Type: Left-lateral strike-slip
• Movement Rate: 2-4 cm/year (highest in Pilipinas)

Major Segments:

• Agusan Segment:
  • Runs through Agusan del Sur and Agusan del Norte
  • Length: Approximately 150 km
  • Affected Areas: Butuan City, Prosperidad, Trento
• Lianga Segment:
  • Location: Surigao del Sur
  • Length: Approximately 80 km
  • Historical Activity: 2017 M6.7 Surigao del Sur earthquake
• Mati Segment:
  • Location: Davao Oriental
  • Length: Approximately 90 km
  • Affected Areas: Mati City, Governor Generoso

4.2 Cotabato Fault System

A complex system of faults in central Mindanao with significant seismic potential.

Makilala-Malungon Fault

• Length: Approximately 90 km
• Type: Strike-slip fault
• Last Major Event: 2019 M6.9 Cotabato earthquake series
• Affected Areas: Makilala, Kidapawan, M'lang, Tulunan

Central Mindanao Fault

• Length: Approximately 120 km
• Recent Activity: 2019 earthquake sequence (M6.3, M6.6, M6.9)
• Affected Provinces: Cotabato, Davao del Sur, Sultan Kudarat

4.3 Davao Fault Systems

Davao City Fault

• Length: Approximately 35 km
• Location: Runs through Davao City
• Type: Strike-slip fault
• Risk Assessment: High due to urban population density

4.4 Surigao Fault Systems

Surigao Segment

• Length: Approximately 60 km
• Last Major Event: 2017 M6.7 Surigao earthquake
• Affected Areas: Surigao City, municipalities of Surigao del Norte
• Impact: Caused significant damage and casualties in 2017

5. Complete Regional Risk Assessment

5.1 High-Risk Metro Areas and Fault Proximity

5.2 Fault Activity Classification

PHIVOLCS classifies faults based on recent geological activity:

Active Faults (Movement within last 10,000 years)

• West Valley Fault
• East Valley Fault
• Pilipino Fault Zone (all segments)
• Cotabato Fault System
• North Bohol Fault
• Negros Fault System
• Surigao Fault

Potentially Active Faults (Movement within last 40,000 years)

• Various segments in Central Luzon
• Some Visayas regional faults
• Portions of Mindanao fault systems

Inactive Faults (No movement >40,000 years)

While classified as inactive, these are still monitored as geological understanding evolves.

6. Seismic Hazard Zones of the Pilipinas

6.1 PHIVOLCS Seismic Hazard Map Classification

The Pilipinas is divided into seismic zones based on expected ground shaking intensity:

6.2 Liquefaction Susceptibility Zones

Areas with high liquefaction risk due to soil composition and water table:

• Metro Manila: Coastal areas of Manila Bay, Laguna de Bay shores, river systems (Pasig, Marikina)
• Pampanga: Reclaimed areas, river delta regions
• Iloilo City: Coastal and reclaimed areas
• Metro Cebu: South Road Properties (SRP) reclaimed land, coastal Mandaue
• Cagayan de Oro: River delta and coastal zones

7. Earthquake Magnitude vs. Fault Length Relationships

7.1 Expected Magnitudes Based on Fault Dimensions

Scientists use fault length and rupture area to estimate maximum credible earthquakes:

8. Understanding Fault Types and Earthquake Impacts

8.1 Strike-Slip Faults (Lateral Movement)

Most common type in the Pilipinas, characterized by horizontal movement.

Impact Characteristics:

• Ground Rupture: Visible surface displacement, infrastructure damage along fault trace
• Shaking Pattern: Intense but localized near fault, rapid attenuation
• Building Damage: Severe for structures directly on fault, moderate within 5 km
• Examples: West Valley Fault, Pilipino Fault Zone

8.2 Reverse/Thrust Faults (Compressional)

One block rides over another due to compressional forces.

Impact Characteristics:

• Ground Uplift: Vertical displacement, permanent elevation changes
• Shaking Pattern: Widespread, can affect larger areas
• Tsunami Risk: Higher for offshore reverse faults
• Examples: North Bohol Fault, Negros Trench

8.3 Normal Faults (Extensional)

Result from pulling apart of crustal blocks.

Impact Characteristics:

• Ground Subsidence: Downward movement of hanging wall
• Shaking Pattern: Moderate intensity, localized
• Secondary Hazards: Landslides, ground settlement
• Examples: Some Central Luzon faults, Macolod Corridor

9. Historical Earthquakes and Associated Faults

9.1 Major Pilipino Earthquakes (1900-Present)

9.2 Lessons from Historical Events

• Surface Rupture Reality: 2013 Bohol earthquake produced 6 km of visible ground displacement, validating fault mapping importance
• Cascading Failures: 1990 Luzon earthquake demonstrated how ground shaking can trigger landslides and building collapses
• Earthquake Sequences: 2019 Cotabato events (M6.3, M6.6, M6.9) showed that major earthquakes can occur in clusters
• Urban Vulnerability: Density of Metro Manila, Cebu, and Davao amplifies risk regardless of fault characteristics

10. Modern Fault Monitoring and Research

10.1 PHIVOLCS Monitoring Network

The Pilipino Institute of Volcanology and Seismology maintains comprehensive fault monitoring:

Seismograph Networks

• Saklaw: 100+ seismic stations nationwide
• Capabilities: Real-time detection, magnitude calculation, epicenter location
• Response Time: Automated alerts within 2-5 minutes of significant events

GPS Monitoring Stations

• Purpose: Measure crustal deformation and fault movement rates
• Saklaw: 50+ GPS stations on major faults
• Katumpakan: Sub-centimeter accuracy for tracking plate motion

Fault Trenching and Paleoseismology

• Method: Excavate trenches across faults to study past earthquake evidence
• Mga Aplikasyon: Determine recurrence intervals, last movement dates
• Recent Studies: West Valley Fault, Pilipino Fault Zone segments

10.2 International Collaboration

• JICA (Japan International Cooperation Agency): West Valley Fault studies, "Big One" scenario modeling
• USGS (United States Geological Survey): Technical assistance, monitoring equipment
• GFZ (German Research Centre for Geosciences): Fault mapping, seismic hazard assessment

11. Practical Fault Risk Assessment for Residents

11.1 How to Determine Your Fault Proximity Risk

Step 1: Check PHIVOLCS Fault Maps

Visit the PHIVOLCS website or offices to access detailed fault maps for your area:

• Website: www.phivolcs.dost.gov.ph
• Main Office: PHIVOLCS Building, C.P. Garcia Avenue, UP Campus, Diliman, Quezon City
• Regional Offices: Available in major cities for local fault information

Step 2: Identify Fault Setback Zones

PHIVOLCS recommends setback distances from active faults:

• Residential Buildings: Minimum 5 meters from fault trace
• Mga Kritikal na Pasilidad (hospitals, schools, government): Minimum 10-15 meters
• Mataas na Gusali: Detailed geological study required if within 100 meters

Step 3: Request Fault Clearance Certification

For property transactions and construction permits:

• Required Documents: Location map, GPS coordinates, survey plan
• Processing Time: 15-30 working days
• Validity: Generally 1 year for construction purposes
• Cost: Variable by location and property size

11.2 Building Safety Based on Fault Distance

12. Comprehensive Preparedness Guide by Region

12.1 Metro Manila Residents (West Valley Fault Zone)

Immediate Actions:

• Verify if your property is within the 5-meter danger zone (use PHIVOLCS Valley Fault System Atlas)
• Inspect building for compliance with National Structural Code of the Pilipinas (NSCP)
• Prepare comprehensive emergency kit with 7-day mga suplay
• Identify evacuation routes and assembly points
• Secure heavy furniture and appliances

Long-Term Planning:

• Consider retrofitting older buildings (pre-2001 construction)
• Purchase earthquake insurance if available
• Participate in community earthquake drills
• Develop family communication and reunion plans

12.2 Visayas Residents (Multiple Fault Systems)

Cebu-Specific:

• Check proximity to Central Cebu Fault and SRP offshore fault
• Assess tsunami risk for coastal areas (dual hazard)
• Ensure compliance with building codes for reclaimed land structures

Bohol-Specific:

• Learn from 2013 earthquake: expect aftershock sequences
• Monitor North Bohol Fault zone for any new construction
• Strengthen heritage structures using appropriate techniques

Leyte-Specific:

• Monitor Pilipino Fault Zone activity reports
• Prepare for potential landslides in mountainous areas
• Establish communication systems for remote communities

12.3 Mindanao Residents (Pilipino Fault Zone, Cotabato System)

Davao Region:

• Verify distance from Davao City Fault and Pilipino Fault
• Prepare for dual hazards: earthquakes and potential volcanic activity (Mt. Apo)
• Ensure critical infrastructure has earthquake-resistant design

Cotabato Region:

• Learn from 2019 earthquake sequence: prepare for multiple strong events
• Monitor Makilala-Malungon Fault system status
• Strengthen traditional structures with appropriate retrofitting

Surigao Region:

• Apply lessons from 2017 M6.7 earthquake
• Monitor Pilipino Fault Surigao Segment activity
• Strengthen coastal structures for combined earthquake-tsunami risk

13. Earthquake-Resistant Construction Standards

13.1 National Structural Code of the Pilipinas (NSCP)

The NSCP provides minimum design standards for earthquake resistance:

Key kinakailangan by Seismic Zone:

13.2 Retrofit Recommendations for Existing Buildings

Mga Gusali Bago ang 2001 (Before NSCP 2001)

• Priyoridad: High - these buildings predate modern seismic codes
• Common Deficiencies: Weak connections, inadequate reinforcement, soft-story vulnerabilities
• Mga Opsyon sa Retrofit:
  • Add steel bracing to mga mga frames
  • Strengthen mga koneksyon ng beam-column
  • Install mga mga base isolators (for important structures)
  • Add mga mga shear walls

2001-2015 Buildings (NSCP 2001-2010)

• Priyoridad: Moderate - meet basic standards but may benefit from upgrades
• Mga Opsyon sa Retrofit:
  • Strengthen mga kritikal na koneksyon
  • Add mga mga supplemental damping systems
  • Upgrade mga mga non-structural elements (kisame, facades)

14. Emergency Response Planning

14.1 Family Emergency Plan Components

Plano sa Komunikasyon

• Pangunahing Kontak: Designate taong makikipag-ugnayan sa labas ng lugar
• Mga Puntong Pagtitipon:
  • Malapit sa bahay na assembly point (within kapitbahayan)
  • Backup na lokasyon (outside immediate area)
  • Rehiyonal na reunification center (malaking paglikas)
• Emergency Numbers: Store in multiple formats (paper, phone, memorized)

Mga Mahalagang Suplay (7-Day Minimum)

14.2 Community Preparedness

Barangay-Level Preparedness

• Organize regular earthquake drills (minimum quarterly)
• Identify vulnerable populations requiring assistance
• Establish community emergency response teams (CERT)
• Map evacuation routes and assembly areas
• Stockpile community emergency mga suplay

Paghahanda sa Lugar ng Trabaho

• Conduct taunang earthquake drills per mga kinakailangan ng DOLE
• Maintain mga mapa ng paglikas and emergency lighting
• Train mga mga floor wardens and mga mga first responders
• Secure mga kagamitan sa opisina and heavy items
• Establish mga protokol sa komunikasyon ng mga empleyado

15. Myths and Facts About Pilipino Faults

15.1 Common Misconceptions

Myth 1: "The West Valley Fault is overdue, so it must happen soon"

Reality: While the average recurrence interval of 400-600 years has been exceeded, earthquakes don't follow strict schedules. The "Big One" could occur tomorrow or decades from now. Recurrence intervals are statistical averages, not predictions.

Myth 2: "Living far from faults means you're safe"

Reality: While proximity to faults increases risk of ground rupture, strong earthquakes can cause damage hundreds of kilometers away. Building quality, soil type, and elevation matter as much as fault distance.

Myth 3: "Small earthquakes relieve pressure and prevent big ones"

Reality: Thousands of small earthquakes would be needed to release energy equivalent to one M7.0+ event. Small quakes don't significantly reduce the likelihood of major earthquakes.

Myth 4: "Earthquake weather exists"

Reality: No scientific correlation exists between weather conditions and earthquakes. Tectonic processes occur deep underground, independent of atmospheric conditions.

Myth 5: "Animals can predict earthquakes days in advance"

Reality: While some animals may sense P-waves seconds before stronger S-waves arrive, there's no scientific evidence of days-in-advance prediction ability.

15.2 Scientific Facts to Remember

• Fact 1: The Pilipinas experiences approximately 20 earthquakes per day, but most are too small to feel (magnitude <3.0)
• Fact 2: A magnitude 7.0 earthquake releases approximately 32 times more energy than a magnitude 6.0
• Fact 3: Aftershocks can continue for months or even years after major earthquakes
• Fact 4: The 1990 Luzon earthquake caused ground displacement visible from space (satellite imagery)
• Fact 5: Modern seismic building codes can reduce earthquake casualties by 80-90%

16. Future Research and Fault Monitoring

16.1 Emerging Technologies

Machine Learning and Mga Aplikasyon ng AI

• Pagkilala ng Pattern: Analyzing decades of seismic data to identify pre-earthquake patterns
• Pagmomodelo ng Panganib: AI-powered simulations of earthquake scenarios and impacts
• Pagpapahusay ng Maagang Babala: Faster, more accurate magnitude estimation

Pagsubaybay sa Satellite (InSAR)

• Pamamaraan: Interferometric Synthetic Aperture Radar measures ground deformation from space
• Katumpakan: Millimeter-level accuracy for tracking fault movement
• Saklaw: Continuous monitoring of remote fault segments

Fiber-Optic Sensing

• Teknolohiya: Use existing fiber-optic cables as distributed seismic sensors
• Mga Kalamangan: Siksik na saklaw ng network, real-time na pagsubaybay
• Mga Aplikasyon: Maagang babala sa lindol sa lunsod, paglalarawan ng fault

16.2 Ongoing Research Projects

• Project NOAH (Nationwide Operational Assessment of Hazards): Multi-hazard mapping including seismic risks
• Metro Manila Earthquake Impact Reduction Study (MMEIRS): Updating "Big One" scenarios with latest data
• Pilipino Fault Zone Study: Comprehensive characterization of all PFZ segments
• Paleoseismology Program: Determining precise recurrence intervals through geological investigation

17. Key Takeaways and Action Items

17.1 Essential Knowledge

1. Know Your Fault: Identify the nearest active fault to your home, workplace, and school
2. Understand Risk Levels: Distance from fault, building age, soil type, and seismic zone all affect risk
3. Recognize Warning Signs: While prediction is impossible, understanding earthquake science helps separate fact from fiction
4. Build Resilience: Earthquake-resistant construction and retrofitting save lives
5. Prepare Comprehensively: 7-day mga suplay, family plans, and community coordination are essential

17.2 Immediate Action Checklist

• ☐ Check PHIVOLCS fault maps for your area
• ☐ Request fault clearance certificate for your property
• ☐ Assess building age and compliance with seismic codes
• ☐ Secure heavy furniture and appliances
• ☐ Assemble 7-day emergency kit
• ☐ Develop family communication and reunion plan
• ☐ Identify evacuation routes and assembly points
• ☐ Participate in earthquake drills
• ☐ Consider earthquake insurance if available
• ☐ Stay informed through PHIVOLCS alerts and updates

18. Resources and Contact Information

18.1 Government Agencies

• PHIVOLCS Main Office:
  • Address: PHIVOLCS Building, C.P. Garcia Avenue, UP Campus, Diliman, Quezon City
  • Hotline: (02) 8426-1468 to 79
  • Email: info@phivolcs.dost.gov.ph
  • Website: www.phivolcs.dost.gov.ph
• National Disaster Risk Reduction and Management Council (NDRRMC):
  • Hotline: 911 (nationwide emergency)
  • Website: www.ndrrmc.gov.ph

18.2 Mga Mga Emergency Hotlines

• Pambansang Emergency Hotline: 911
• PHIVOLCS Impormasyon sa Lindol: (02) 8426-1468 to 79
• Metro Manila Development Authority (MMDA): 136
• Pilipino Red Cross: 143

References and Further Reading

• PHIVOLCS (2023). "Active Faults in the Pilipinas: Distribution and Characteristics"
• PHIVOLCS (2021). "Atlas ng Valley Fault System"
• JICA & PHIVOLCS (2015). "Pag-aaral ng Pagbawas ng Epekto ng Lindol sa Metropolitan Manila (MMEIRS)"
• National Structural Code of the Pilipinas (NSCP 2015)
• Mga Bulletin at Publikasyon ng PHIVOLCS sa Lindol (iba't ibang taon)
• Bautista, B.C. & Oike, K. (2000). "Estimation of the magnitudes and epicenters of Pilipino historical earthquakes"
• Rimando, R.E. & Knuepfer, P.L. (2006). "Neotectonics ng Marikina Valley Fault System (MVFS)"