Introduction: Understanding the Marikina Valley Fault System
The Marikina Valley Fault System (MVFS) represents one of the most significant seismic threats to Metro Manila and surrounding provinces. Composed of two parallel fault lines—the West Valley Fault and East Valley Fault—this active fault system stretches approximately 146 kilometers from Bulacan to Laguna, directly traversing densely populated urban areas including Quezon City, Marikina, Pasig, Makati, Taguig, and numerous municipalities in Rizal and Laguna provinces.
What makes the MVFS particularly dangerous is not just its proximity to 15 million people, but its proven history of generating destructive earthquakes. The West Valley Fault alone is capable of producing a magnitude 7.2 earthquake—commonly referred to as "The Big One"—which could result in catastrophic damage, tens of thousands of casualties, and economic losses exceeding ₱2.5 trillion according to PHIVOLCS and Metro Manila Earthquake Impact Reduction Study (MMEIRS) assessments.
Understanding both segments of the MVFS—their characteristics, behavior patterns, historical activity, and potential impacts—is critical for effective earthquake preparedness. This comprehensive guide provides the most detailed analysis available of the Marikina Valley Fault System, synthesizing decades of geological research, recent scientific findings, risk assessments, and actionable preparedness strategies for residents, businesses, and local government units along the fault.
Critical Information
- Last Major Movement (WVF): 1658 (367 years ago)
- Recurrence Interval: 400-600 years
- Expected Magnitude: 7.2 (West Valley Fault)
- Population at Risk: 15+ million people
- Estimated Casualties: 34,000+ deaths, 114,000+ injuries
- Economic Impact: ₱2.5+ trillion
- Current Status: Both faults are within recurrence window and capable of generating major earthquakes
1. The Marikina Valley Fault System: Geological Overview
1.1 Formation and Tectonic Context
The Marikina Valley Fault System formed as part of the complex tectonic environment of the Pilipinas, which sits at the convergent boundary of the Pilipino Sea Plate and Eurasian Plate. The MVFS specifically represents a left-lateral strike-slip fault system—meaning the opposite sides of the fault move horizontally past each other during an earthquake.
The valley itself was created through millions of years of fault movement and erosion, forming the distinctive topographic depression that now hosts the Marikina River and surrounding floodplains. This geological feature is clearly visible on elevation maps and terrain analysis, providing dramatic evidence of the fault system's long-term activity.
1.2 West Valley Fault vs. East Valley Fault
| Characteristic | West Valley Fault (WVF) | East Valley Fault (EVF) |
|---|---|---|
| Total Length | ~100 km | ~10 km (identified segments) |
| Geographic Extent | Bulacan (Doña Remedios Trinidad) to Laguna (Calamba) | Rodriguez (Rizal) to San Mateo (Rizal) |
| Major Cities Affected | Quezon City, Marikina, Pasig, Makati, Taguig, Muntinlupa, Parañaque, Las Piñas | Rodriguez, San Mateo, parts of Quezon City |
| Fault Type | Left-lateral strike-slip | Left-lateral strike-slip |
| Maximum Magnitude | 7.2 (PHIVOLCS estimate) | 6.2 - 6.5 (estimated) |
| Last Major Movement | 1658 (historical record) | Unknown (insufficient paleoseismic data) |
| Recurrence Interval | 400-600 years | Insufficient data |
| Surface Expression | Clearly visible; well-mapped | Less pronounced; partially mapped |
| Slip Rate | 2-3 mm/year | Insufficient data |
| Research Status | Extensively studied; multiple paleoseismic trenching investigations | Limited studies; requires additional investigation |
| Risk Level | VERY HIGH - capable of "Big One" scenario | MODERATE TO HIGH - significant local impact potential |
1.3 Fault Segmentation
The West Valley Fault is divided into multiple segments based on geometric complexity, historical rupture patterns, and structural characteristics. Understanding these segments is crucial because they can rupture independently or together:
| Segment | Location | Length (km) | Key Characteristics | Cities/Municipalities Affected |
|---|---|---|---|---|
| Northern Segment | Bulacan to northern Quezon City | ~30 | Passes through less urbanized areas; moderately steep terrain | Doña Remedios Trinidad, Norzagaray, San Jose del Monte, Quezon City (Fairview, La Mesa) |
| Central Segment | Central Quezon City through Marikina to Taguig | ~40 | Most urbanized section; highest population density; traverses Metro Manila core | Quezon City, Marikina, Pasig, Makati, Taguig, Pateros |
| Southern Segment | Southern Metro Manila to Laguna | ~30 | Mixed urban-rural; crosses Laguna de Bay area | Muntinlupa, Parañaque, Las Piñas, Biñan, Santa Rosa, Calamba |
Scientific Note: Cascading Rupture Risk
Recent research suggests that a rupture initiated in one segment could potentially trigger ruptures in adjacent segments through stress transfer mechanisms. This "cascading rupture" scenario could result in the entire 100-kilometer fault rupturing simultaneously, producing the maximum magnitude 7.2 earthquake. This represents the worst-case "Big One" scenario modeled by PHIVOLCS.
2. Historical Seismic Activity and Paleoseismology
2.1 The 1658 Earthquake: Last Major WVF Rupture
The most recent major earthquake attributed to the West Valley Fault occurred in 1658 during the Spanish colonial period. Historical accounts describe devastating shaking that destroyed churches and buildings in Manila and surrounding areas. Key details from historical records include:
- Date: Sometime in 1658 (exact date uncertain)
- Estimated Magnitude: 7.0 - 7.5 based on damage descriptions
- Impact: Widespread destruction in Manila; numerous buildings collapsed including stone churches
- Casualties: Historical records incomplete, but significant loss of life documented
- Duration: Described as "very long" shaking, consistent with major fault rupture
Critical Implication: As of 2025, 367 years have elapsed since this last major rupture. With a recurrence interval of 400-600 years, the West Valley Fault is statistically within its earthquake generation window and could rupture at any time.
2.2 Paleoseismic Evidence
PHIVOLCS and international research teams have conducted multiple paleoseismic trenching studies along the West Valley Fault to understand its long-term behavior. These excavations reveal layered evidence of past earthquakes preserved in the geological record:
| Trenching Site | Location | Key Findings | Number of Paleoearthquakes Identified |
|---|---|---|---|
| La Mesa Dam Site | Quezon City | Evidence of multiple surface ruptures; most recent consistent with 1658 event | At least 3-4 events in past 1,500-2,000 years |
| UP Diliman Campus | Quezon City | Clear fault scarp; stratigraphic evidence of repeated displacement | Multiple events identified |
| Marikina River Site | Marikina City | Fault zone crosses river valley; evidence of lateral displacement | At least 2-3 events |
| Muntinlupa Site | Muntinlupa City | Southern segment activity documented | Multiple events |
Research Finding: Consistent Recurrence Pattern
Paleoseismic analysis reveals that the West Valley Fault generates major earthquakes (magnitude 7+) approximately every 400-600 years. This recurrence pattern has been consistent over at least the past several thousand years, providing strong scientific basis for current earthquake preparedness efforts. The fault appears to accumulate stress relatively steadily at 2-3 mm/year, eventually releasing this energy in catastrophic ruptures.
2.3 Recent Instrumental Seismicity (1900-2025)
Since the establishment of modern seismic monitoring in the Pilipinas, the Marikina Valley Fault System has remained relatively quiet with no major earthquakes. However, numerous small to moderate earthquakes have been recorded in the vicinity:
| Date | Magnitude | Location | Depth | Significance |
|---|---|---|---|---|
| Various (ongoing) | 1.0 - 3.5 | Along WVF trace | Shallow (<10 km) | Background seismicity; stress adjustment along fault |
| Periodic clusters | 2.0 - 4.0 | Near fault intersections | 5-15 km | May indicate stress concentration zones |
| 2024-2025 | 2.5 - 3.8 | Rodriguez, San Mateo area | Shallow | Increased monitoring; possible precursory activity (uncertain) |
Important Clarification: Seismic Quiet ≠Safe
The absence of major earthquakes over the past 367 years does NOT mean the fault is inactive or safe. In fact, the opposite is true: the longer the time since the last major earthquake, the closer we statistically are to the next one. This period of seismic quiet represents stress accumulation, not stress release. The West Valley Fault is locked and loading, building up the energy that will eventually be released in "The Big One."
3. "The Big One" Scenario: Comprehensive Impact Assessment
3.1 PHIVOLCS Magnitude 7.2 Scenario
PHIVOLCS, in collaboration with Japanese and international seismologists, developed a comprehensive earthquake scenario for a magnitude 7.2 rupture of the West Valley Fault. This scenario, known as "The Big One," represents the most scientifically rigorous impact assessment available:
Ground Shaking Intensity Distribution
| Distance from Fault | Expected PEIS Intensity | Description | Areas Affected |
|---|---|---|---|
| 0 - 5 km | Intensity IX - X (Devastating to Completely Devastating) | Extreme shaking; most buildings severely damaged or collapsed | Areas directly along fault: parts of QC, Marikina, Pasig, Makati, Taguig, Muntinlupa |
| 5 - 10 km | Intensity VIII - IX (Very Destructive to Devastating) | Very strong shaking; significant structural damage | Most of Metro Manila; central business districts |
| 10 - 20 km | Intensity VII - VIII (Destructive to Very Destructive) | Strong shaking; moderate to heavy damage to buildings | Outer Metro Manila; Rizal province; parts of Cavite, Laguna, Bulacan |
| 20 - 50 km | Intensity V - VII (Strong to Destructive) | Moderate to strong shaking; light to moderate damage | Greater Metro Manila area; Cavite, Laguna, Batangas, Bulacan, Pampanga |
| 50 - 100+ km | Intensity III - V (Weak to Strong) | Noticeable to strong shaking; generally minor damage | Central Luzon; parts of Southern Luzon |
3.2 Casualty Estimates
The Metro Manila Earthquake Impact Reduction Study (MMEIRS) and PHIVOLCS provide the following casualty estimates for a daytime magnitude 7.2 West Valley Fault earthquake:
| Category | Estimated Numbers | Primary Causes |
|---|---|---|
| Deaths | 33,500 - 34,000 | Building collapse, falling debris, secondary hazards (fire, landslides) |
| Injuries (serious) | 114,000+ | Building collapse, falling objects, evacuation injuries |
| Displaced Persons | 2.5 - 3.4 million | Building damage/destruction, fear of aftershocks, infrastructure failure |
| Buildings Damaged | 340,000+ residential units | Ground shaking, surface rupture, secondary effects |
| Buildings Destroyed | 168,000+ residential units | Severe ground shaking, fault surface rupture, fire following earthquake |
Time-of-Day Variation in Casualties
Casualty estimates vary significantly depending on when the earthquake occurs:
- Daytime (business hours): 34,000 deaths (baseline scenario)
- Nighttime (2-4 AM): Potentially higher casualties due to people sleeping and slower response
- Peak rush hour: Significantly higher casualties due to people in transit, traffic congestion, collapse of elevated roads
- School hours: Particular concern for schools along fault; potential for high student casualties in non-compliant buildings
3.3 Infrastructure Damage Assessment
Critical Infrastructure at Risk
| Infrastructure Type | Specific Assets at Risk | Expected Impact | Consequences |
|---|---|---|---|
| Water Supply | La Mesa Dam, Angat-Ipo-La Mesa water system, distribution pipes | Severe: dam potentially compromised; widespread pipe failure | Water supply disruption to 12+ million people for weeks to months |
| Transportation | EDSA, C-5, Commonwealth Ave, Ortigas Ave, MRT/LRT lines, NLEX/SLEX connectors | Severe: road damage, bridge collapse, rail system failure | Complete transportation gridlock; emergency response severely hampered |
| Power Grid | Transmission lines, substations, distribution network | Severe: widespread power infrastructure damage | Total blackout in Metro Manila for days; partial restoration taking weeks |
| Communications | Cell towers, fiber optic networks, broadcasting stations | Moderate to Severe: tower collapse, network overload, power loss | Communication breakdown; emergency coordination extremely difficult |
| Healthcare | Hospitals, clinics, emergency facilities along fault | Severe: structural damage to medical facilities; equipment failure | Medical capacity overwhelmed while facilities themselves damaged/destroyed |
| Schools | 1,000+ school buildings along or near fault | Severe: many non-compliant buildings at high collapse risk | Mass casualties if earthquake occurs during school hours |
| Commercial | Shopping malls, office buildings, markets in CBDs | Moderate to Severe: variable depending on building compliance | Economic paralysis; thousands trapped in collapsed structures |
| Residential | 500,000+ residential structures in high-intensity zones | Severe: 168,000+ complete collapses; 340,000+ damaged | Housing crisis; 3+ million displaced persons |
3.4 Economic Impact Projections
The economic consequences of "The Big One" are staggering, with impacts extending far beyond immediate destruction:
| Impact Category | Estimated Cost (₱ Billion) | Timeframe | Components |
|---|---|---|---|
| Direct Physical Damage | ₱1,800 - ₱2,000 | Immediate | Buildings, infrastructure, equipment, inventory losses |
| Business Interruption | ₱300 - ₱500 | First year | Lost productivity, supply chain disruption, closed businesses |
| Emergency Response & Relief | ₱50 - ₱100 | First 6 months | Search & rescue, medical response, temporary shelters, food/water distribution |
| Temporary Housing | ₱150 - ₱200 | 6-24 months | Transitional shelters for 3+ million displaced |
| Reconstruction Costs | ₱200 - ₱300 | 3-5 years | Beyond direct damage; includes improved building standards |
| Long-term Economic Impact | ₱500 - ₱1,000+ | 5-10 years | GDP reduction, investment loss, talent migration, opportunity costs |
| TOTAL ESTIMATED IMPACT | ₱2,500 - ₱4,100+ | Multi-year | Comprehensive economic disruption |
Context: Economic Scale
To put these numbers in perspective:
- ₱2.5 trillion represents approximately 11-13% of Pilipino GDP
- This is larger than the entire national budget for a typical year
- Economic recovery would take at least 10-15 years to return to pre-earthquake trajectory
- Metro Manila contributes ~37% of Pilipino GDP; prolonged disruption would trigger national economic crisis
4. Comprehensive Risk Assessment by City/Municipality
4.1 Metro Manila Cities
Quezon City
| Risk Factor | Assessment | Details |
|---|---|---|
| Fault Crossing | EXTREME | West Valley Fault crosses through Fairview, Commonwealth, UP Diliman, Tandang Sora, La Mesa area |
| Population Exposure | EXTREME | 3+ million residents; densest city in Metro Manila |
| Critical Infrastructure | EXTREME | La Mesa Dam (water supply to 12M people), major hospitals, government offices, universities |
| Building Vulnerability | HIGH to EXTREME | Mix of old non-compliant and newer compliant buildings; many informal settlements |
| Expected Intensity | VIII - X | Varies by distance from fault; Intensity X along fault trace |
| Secondary Hazards | HIGH | La Mesa Dam failure potential, landslides in upland areas, fire following earthquake |
| Overall Risk Level | EXTREME | Highest-risk city; fault crossing + high population + critical infrastructure |
Marikina City
| Risk Factor | Assessment | Details |
|---|---|---|
| Fault Crossing | EXTREME | Fault crosses along Marikina Valley; city namesake |
| Population Exposure | HIGH | ~500,000 residents in compact urban area |
| Critical Infrastructure | HIGH | Major transport corridors, residential zones, commercial centers |
| Building Vulnerability | MODERATE to HIGH | Newer developments generally compliant; older areas vulnerable |
| Expected Intensity | VIII - X | Extreme shaking along fault; amplification in valley sediments |
| Secondary Hazards | MODERATE | Liquefaction potential in river valley; flooding risk |
| Overall Risk Level | EXTREME | Direct fault crossing; significant population exposure |
Makati City
| Risk Factor | Assessment | Details |
|---|---|---|
| Fault Crossing | EXTREME | Fault crosses through parts of Makati; proximity to CBD |
| Population Exposure | EXTREME | 600,000+ residents; 1M+ daytime population (workers/visitors) |
| Critical Infrastructure | EXTREME | Financial district; numerous high-rise buildings; hospitals; embassies |
| Building Vulnerability | MODERATE | Many modern buildings code-compliant, but some older structures vulnerable |
| Expected Intensity | VIII - IX | Very strong to devastating shaking |
| Secondary Hazards | HIGH | High-rise vulnerability; glass and debris cascade; fire risk in dense areas |
| Economic Impact | EXTREME | Financial center disruption would have national/international economic consequences |
| Overall Risk Level | EXTREME | Economic epicenter at severe risk; massive daytime population exposure |
Pasig City, Taguig City, Muntinlupa City
All three cities have EXTREME risk levels due to direct fault crossings, high population density, significant commercial and residential development, and critical infrastructure presence. Each faces Intensity VIII-X shaking and potential for severe casualties and infrastructure damage.
4.2 Rizal Province Municipalities
| Municipality | Risk Level | Key Risk Factors | Expected Intensity |
|---|---|---|---|
| Rodriguez (Montalban) | EXTREME | Both WVF and EVF proximity; mountainous terrain; landslide risk; growing population | VIII - X |
| San Mateo | EXTREME | East Valley Fault crosses town; steep terrain; densely populated valley areas | VIII - X |
| Antipolo | HIGH | Near fault; hillside developments vulnerable to landslides; rapid urbanization | VII - IX |
| Cainta | HIGH | Proximity to fault; dense residential areas; commercial development | VII - IX |
| Taytay | MODERATE to HIGH | Near fault zone; growing population; mixed building compliance | VII - VIII |
4.3 Laguna Province Municipalities
| Municipality | Risk Level | Key Risk Factors | Expected Intensity |
|---|---|---|---|
| Biñan | EXTREME | Fault crosses city; high population density; commercial/industrial areas | VIII - X |
| Santa Rosa | HIGH to EXTREME | Near fault; major industrial estates; significant population | VII - IX |
| Calamba | HIGH | Southern terminus of fault; industrial city; Laguna de Bay proximity | VII - IX |
| San Pedro | HIGH | Near fault zone; densely populated; rapid development | VII - VIII |
5. Preparedness Strategies for MVFS-Affected Areas
5.1 Building Safety Assessment
For residents and businesses located within 5 kilometers of the West Valley Fault, building safety is the single most important preparedness factor:
Priyoridad Actions for Building Occupants
- Structural Assessment: Hire licensed structural engineers to evaluate your building's earthquake resistance. Focus on:
- Building age and construction type
- NSCP compliance status
- Foundation integrity
- Structural reinforcement
- Non-structural hazards (heavy fixtures, glass, utilities)
- Retrofitting: If assessment reveals deficiencies, prioritize seismic retrofitting:
- Foundation strengthening
- Structural bracing and reinforcement
- Securing mga non-structural elements
- Upgrading critical systems (electrical, plumbing)
- Relocation Consideration: For buildings deemed severely vulnerable (especially informal settlements and very old structures directly on the fault), relocation may be the only effective mitigation strategy.
5.2 Household Emergency Preparedness
Mga Mahalagang Suplay (Minimum 7-Day Supply)
| Category | Items | Quantity per Person | Storage Notes |
|---|---|---|---|
| Water | Potable water | 21-28 liters (3-4 liters/day) | Store in food-grade containers; rotate every 6 months |
| Food | Hindi madaling masira, ready-to-eat | 7+ days supply | Canned goods, crackers, energy bars; check expiration dates |
| Medical | First aid kit, prescription meds | 7+ days supply | Include personal medications, basic first aid mga suplay |
| Light & Power | Ilaws, baterya, power banks | Multiple per household | Test monthly; replace baterya regularly |
| Communication | Battery/solar radyo, whistle | 1-2 per household | Store with emergency kit; test functionality |
| Tools | Multi-tool, wrench (gas shutoff), crowbar | 1 set per household | Include tools for self-rescue and utility shutoff |
| Sanitation | Toilet mga suplay, hygiene items, trash bags | 7+ days supply | Critical given likely water/sewer system failure |
| Documents | IDs, property docs, insurance, contacts | Waterproof copies | Store in waterproof container; include digital backups |
| Cash | Small bills and at papel na pera | ₱5,000 - ₱10,000 | ATMs and electronic payment will not function |
5.3 Family Emergency Planning
Critical Planning Elements
- Evacuation Plans:
- Primary and alternative evacuation routes from home, work, school
- Designated meeting points (kapitbahayan, city-level, out-of-region)
- Transportation plans (assuming roads may be impassable)
- Communication Strategy:
- Out-of-region contact person (relay point if local communication fails)
- List of all family member contacts, schools, workplaces
- Alternative communication methods (SMS often works when voice calls don't)
- Special Needs Considerations:
- Elderly family members: mobility aids, medications, care kinakailangan
- Infants/children: formula, diapers, comfort items, child care arrangements
- Pets: carriers, food/water, identification, veterinary records
- People with disabilities: specialized equipment, medications, care needs
- Practice Drills:
- Conduct household earthquake drills quarterly
- Practice Drop-Cover-Hold
- Test evacuation routes and meeting points
- Review and update plans annually
5.4 Business Continuity Planning
Businesses located in MVFS-affected areas must develop comprehensive earthquake business continuity plans:
Business Continuity Checklist
- Structural Safety: Professional seismic assessment and retrofitting of business facilities
- Data Protection: Offsite data backups; cloud-based systems; redundant IT infrastructure
- Alternative Operations: Identify backup facilities outside fault zone; remote work capabilities
- Supply Chain Resilience: Diversify suppliers; maintain emergency inventory; establish alternative logistics routes
- Employee Safety: Earthquake preparedness training; emergency communication systems; family support programs
- Financial Preparedness: Earthquake insurance; emergency cash reserves; line of credit arrangements
- Stakeholder Communication: Plans for communicating with customers, suppliers, investors, government agencies post-disaster
5.5 Community-Level Preparedness
Effective earthquake response requires coordinated community action. Barangays and municipalities along the MVFS should implement:
- Community Emergency Response Teams (CERT): Train residents in search & rescue, first aid, emergency management
- Evacuation Planning: Identify safe evacuation areas; establish evacuation routes; conduct community drills
- Critical Infrastructure Protection: Seismic retrofitting of government buildings, schools, health centers, evacuation facilities
- Emergency Stockpiles: Community-level emergency mga suplay, medical equipment, rescue tools
- Communication Systems: Ham radyo networks; community alert systems; regular information dissemination
- Vulnerable Population Support: Identify and plan for elderly, disabled, impoverished residents requiring special assistance
- Regular Drills: Community-wide earthquake drills at least annually; participation in Metro-wide Shake Drills
6. Government Initiatives and Monitoring
6.1 PHIVOLCS Monitoring and Early Warning
PHIVOLCS maintains continuous monitoring of the Marikina Valley Fault System through:
- Seismograph Network: Dense network of seismic sensors detecting earthquake activity in real-time
- GPS Monitoring: Continuous GPS stations measuring ground deformation and strain accumulation
- Paleoseismic Studies: Ongoing trenching investigations to understand fault behavior and recurrence patterns
- Ground Penetrating Radar: Subsurface imaging to map fault traces in urban areas
- Public Information: Regular updates, hazard maps, educational materials available at www.phivolcs.dost.gov.ph
Important Note: No Earthquake Prediction
Despite sophisticated monitoring, earthquakes cannot be predicted. Scientists cannot forecast when the next major earthquake will occur—it could be today, next year, or decades from now. The only certainty is that it WILL happen. Monitoring helps us understand the fault's behavior and provides data for scenario planning, but cannot provide specific advance warning of when an earthquake will strike.
6.2 Metro Manila Earthquake Contingency Plan
The National Disaster Risk Reduction and Management Council (NDRRMC), MMDA, and local government units have developed comprehensive earthquake contingency plans including:
- Pre-Disaster Risk Reduction: Building code enforcement; land use planning; infrastructure retrofitting; public education
- Emergency Response: Rapid deployment plans for search & rescue, medical response, fire suppression, mass care
- Coordination Mechanisms: Incident command systems; inter-agency coordination protocols; resource mobilization
- Recovery Planning: Debris management; temporary housing; infrastructure restoration; economic recovery
6.3 Building Code Enforcement
The National Structural Code of the Pilipinas (NSCP) 2015 and subsequent updates mandate earthquake-resistant design for all new construction and major renovations. Key provisions include:
- Seismic Zone 4 Classification: Metro Manila and surrounding areas classified as highest seismic risk zone
- Fault Setback Zones: Restricted construction within 5 meters of identified active faults
- Structural Design kinakailangan: Mandatory seismic analysis and design for all buildings
- Inspection and Certification: Required structural inspections and engineer certification for building permits
7. What to Do When the Earthquake Strikes
7.1 During the Earthquake: Drop, Cover, Hold
When you feel shaking or receive an earthquake alert:
- DROP: Drop to hands and knees (protects from falling but allows movement)
- COVER: Take cover under a sturdy desk or table; cover head and neck with arms
- HOLD: Hold on to your shelter and be prepared to move with it
- STAY: Stay in position until shaking stops (major earthquake may last 30-90 seconds)
Special Situations
| Location | Action |
|---|---|
| In bed | Stay in bed; cover head with pillow; hold on |
| Outside | Move away from buildings, trees, power lines, streetlights; drop and cover |
| Driving | Pull over safely away from overpasses, buildings, power lines; stay in vehicle |
| In elevator | DO NOT USE ELEVATORS; if trapped when shaking starts, get low and cover head |
| In high-rise | Drop-Cover-Hold; DO NOT run outside or use elevators; expect fire alarms and sprinklers |
| In crowded space | Take cover where you are; avoid rushing for exits (stampede danger) |
7.2 Immediately After Shaking Stops
- Check for injuries: Provide first aid; do not move seriously injured unless immediate danger
- Inspect building damage: Look for structural damage, gas leaks, electrical hazards
- Shut off utilities if necessary: Gas (if leak suspected), electricity (if damage), water (if pipes broken)
- Prepare for aftershocks: Major earthquakes followed by numerous aftershocks (some potentially damaging)
- Evacuate if building unsafe: Use stairs (never elevators); watch for falling debris outside
- Listen for information: Battery radyo for official emergency information and instructions
- Check on neighbors: Especially elderly, disabled, or those needing assistance
7.3 Aftershock Safety
A magnitude 7.2 mainshock will generate hundreds of aftershocks, including potentially:
- Magnitude 6+ aftershocks: Strong enough to cause additional damage to already-weakened structures
- Duration: Aftershocks continue for weeks to months, gradually decreasing in frequency and magnitude
- Danger: Buildings damaged in mainshock may collapse in strong aftershocks
- Safety: Do not re-enter damaged buildings; sleep away from damaged structures; stay alert
8. Long-Term Recovery and Resilience
8.1 Recovery Timeline Expectations
Recovery from "The Big One" will be a multi-year process:
| Timeframe | Phase | Key Activities | Expected Conditions |
|---|---|---|---|
| 0-72 hours | Emergency Response | Search & rescue; emergency medical care; firefighting; initial assessments | Chaotic; limited communications; infrastructure failure; ongoing aftershocks |
| 4-30 days | Early Recovery | Continued search & rescue; mass care; temporary shelters; debris clearing; utility restoration begins | Gradual stabilization; partial utility restoration; supply chain challenges |
| 1-6 months | Transitional Recovery | Transitional housing; major infrastructure repair; business reopening; damage assessments complete | Basic services partially restored; significant displacement continues; economic disruption |
| 6-24 months | Reconstruction | Permanent housing construction; major infrastructure rebuilding; economic recovery efforts | Gradual return to normalcy; many still displaced; visible reconstruction progress |
| 2-5 years | Recovery & Rebuilding | Comprehensive reconstruction; improved building standards; economic recovery | Most infrastructure restored; population returning; economy recovering |
| 5-10+ years | Long-term Recovery | Complete rebuilding; resilience improvements; economic return to pre-earthquake trajectory | Near-complete physical recovery; ongoing economic and social recovery |
8.2 Building Back Better
Post-earthquake reconstruction offers opportunity to enhance resilience:
- Stricter Building Codes: Enhanced seismic standards for reconstruction
- Land Use Planning: Restrict development on fault traces; relocate high-risk settlements
- Infrastructure Resilience: Rebuild critical infrastructure with redundancy and enhanced seismic resistance
- Community Resilience: Strengthen social cohesion and community disaster response capabilities
- Economic Diversification: Reduce concentration of economic activity in vulnerable areas
9. Key Takeaways and Action Steps
Immediate Action Checklist
- ✅ Assess your building: Hire structural engineer if you live/work within 5 km of WVF
- ✅ Prepare emergency mga suplay: Minimum 7-day supply of water, food, medical mga suplay, and essentials
- ✅ Create family emergency plan: Evacuation routes, meeting points, communication strategy
- ✅ Secure your space: Anchor heavy furniture, secure water heaters, identify safe spots
- ✅ Get earthquake insurance: Standard homeowner's insurance does NOT cover earthquake damage
- ✅ Practice Drop-Cover-Hold: Conduct household drills quarterly
- ✅ Stay informed: Follow PHIVOLCS updates; understand your local evacuation plans
- ✅ Participate in community preparedness: Join or support local CERT programs
Remember:
- The West Valley Fault WILL generate a major earthquake—the only question is when
- Preparedness dramatically reduces casualties and accelerates recovery
- Building safety is the most important factor in survival
- Individual, family, community, and government preparedness all contribute to resilience
- The time to prepare is NOW—before the earthquake strikes
10. Additional Resources
Government Agencies
- PHIVOLCS: www.phivolcs.dost.gov.ph - Earthquake monitoring, hazard maps, educational materials
- NDRRMC: National Disaster Risk Reduction and Management Council - Disaster preparedness and response coordination
- OCD: Office of Civil Defense - Regional disaster preparedness offices
- MMDA: Metro Manila Development Authority - Metro-wide disaster management
Educational Materials
- PHIVOLCS "Ready for the Big One" campaign materials
- Metro Manila Shake Drill guidelines and resources
- Earthquake preparedness guides for households, schools, and businesses
- Fault maps and hazard assessments for specific locations
Mga Mga Emergency Hotlines
- NDRRMC Operations Center: 911 (emergency hotline)
- PHIVOLCS: (02) 8426-1468 to 79
- Red Cross: 143
- Local Government Emergency Operations Centers: Contact your city/municipality
Disclaimer: This guide provides general information based on current scientific understanding and government assessments as of January 2025. Earthquake science continues to evolve, and readers should consult official government sources (particularly PHIVOLCS) for the most current information. Individual preparedness needs vary based on specific location, building type, and personal circumstances. Professional consultation is recommended for structural assessments and specialized preparedness planning.