🏘️ Lesson 13: Effects of Earthquake Hazards on Communities and the Environment 

🎯 Learning Objectives

By the end of this lesson, you should be able to:

• 🧠 Cognitive: Analyze the different effects of earthquake hazards.

• 💛 Affective: Express willingness to participate in earthquake preparedness activities.

• ✋ Psychomotor: Create a simple infographic showing earthquake effects and safety measures.

1️⃣ Quick Reminder: Earthquake Hazards = More Than Shaking

A strong earthquake can trigger multiple hazards at once, not just ground shaking.
These hazards affect:

• People (health, safety, emotions)

• Infrastructure (homes, roads, schools, hospitals, utilities)

• Environment (land, rivers, coastlines, ecosystems)

• Economy & society (income, schooling, services, community life)

2️⃣ Effects of Specific Earthquake Hazards

✅ A. Ground Shaking

Main effect: everything moves violently.

Effects on people:

• injuries from falling objects

• deaths from building collapse

• panic, fear, trauma

• displacement due to unsafe homes
  
  

Effects on infrastructure:

• buildings crack or collapse

• bridges/roads break

• power, water, communication lines fail

• hospitals and schools stop operations
  
  

Environmental effects:

• triggers landslides

• changes river paths

• damages soil stability
  
  

Community impact:

• evacuation centers crowded

• services disrupted

• livelihoods paused because workplaces damaged
  
  

✅ B. Ground Rupture

Main effect: the ground splits open along fault lines.

Effects on people:

• sudden destruction of homes near faults

• injuries from cracks/breaks

• forced relocation (unsafe land)
  
  

Effects on infrastructure:

• houses, roads, pipelines cut in half

• railways distorted

• foundations permanently damaged

• rebuilding becomes harder because land is offset
  
  

Environmental effects:

• permanent landscape changes

• soil displacement
  
  

Community impact:

• long-term land-use restriction near faults

• permanent zoning changes
  
  

✅ C. Liquefaction

Main effect: soil weakens and acts like liquid.

Effects on people:

• houses tilt/sink → injuries, displacement

• drowning risks if ground sinks in flooded areas

• stress due to sudden housing loss
  
  

Effects on infrastructure:

• buildings tilt even without collapsing

• roads buckle, crack, or sink

• buried pipes break → water contamination

• ports and airports become unsafe
  
  

Environmental effects:

• sand boils and ground cracks

• damage to wetlands/coastal land
  
  

Community impact:

• whole neighborhoods become unlivable

• recovery takes long because soil must stabilize
  
  

✅ D. Earthquake-Induced Landslides

Main effect: soil/rocks slide downhill.

Effects on people:

• burial of homes and residents

• injuries from debris flow

• isolated communities

• loss of life in steep areas
  
  

Effects on infrastructure:

• roads and bridges blocked/destroyed

• power lines down

• communities cut off from rescue

• rivers blocked → possible flash flooding
  
  

Environmental effects:

• loss of forests and wildlife habitats

• river siltation (muddy rivers)

• increased erosion risk
  
  

Community impact:

• forced relocation

• loss of farmland

• repeated risk if slopes stay unstable
  
  

✅ E. Ground Subsidence / Lateral Spreading (brief reminder)

Subsidence: ground sinks → roads crack, lowlands flood more easily
Lateral spreading: soil shifts sideways → foundations and bridges pull apart

✅ F. Tsunami (if earthquake is offshore)

Effects on people: drowning, displacement, trauma
Infrastructure: coastal homes swept away, ports destroyed
Environment: saltwater intrusion, coral/mangrove damage
Community: coastal livelihood collapse (fishing, tourism)

3️⃣ Social and Economic Consequences of Earthquake Hazards

Earthquake hazards don’t stop at physical damage — they affect how communities live.

Social effects

• displacement and long stays in evacuation centers

• interruption of classes and schooling

• family separation

• emotional trauma and fear of aftershocks

• health risks in crowded shelters
  
  

Economic effects

• loss of livelihood (shops, farms, workspaces damaged)

• expensive rebuilding costs

• inflation in basic goods

• government resources shifted to recovery

• long-term poverty risk for affected families

4️⃣ Importance of Preparedness and Mitigation

Earthquakes cannot be prevented, but their effects can be reduced.

✅ Preparedness means:

• knowing hazards in your area

• having Go Bags ready

• practicing drills

• identifying evacuation routes

• having communication plans

• making homes safer (secure shelves, reinforce structures)
  
  

✅ Mitigation means:

• building structures that follow earthquake codes

• avoiding fault zones and unstable slopes

• strengthening infrastructure

• creating hazard maps and land-use plans
  
  

Preparedness reduces fear. Mitigation reduces damage.