Understanding Natural Hazards and Their Impact

Introduction to Natural Hazards

• Natural hazards are processes that can cause property damage, injuries, or fatalities.
• Classified into geological (earthquakes, volcanic eruptions, landslides), hydrometeorological (tropical cyclones, floods), and coastal hazards (erosion, saltwater intrusion).
• Understanding these hazards aids in preparation and mitigation strategies.

Earthquakes: Causes and Effects

• Earthquakes result from tectonic plate movements; impacts include surface rupture, ground shaking, subsidence, liquefaction, and tsunamis.
• Types of earthquakes:
  • Tectonic Earthquakes: Most common, e.g., the 1990 Luzon earthquake linked to the Digdig Fault.
  • Volcanic Earthquakes: Triggered by magma movement, e.g., the 1991 Mount Pinatubo eruption.
  • Collapse Earthquakes: Result from underground voids, e.g., the 2012 Negros Oriental earthquake.
  • Human-Induced Earthquakes: Linked to activities like mining and fracking, e.g., the 2017 Leyte earthquake.

Earthquake Outcomes

• Surface Rupture: Ground breaks along fault lines causing physical damage; illustrated by the 1906 San Francisco earthquake.
• Ground Shaking: Seismic waves causing collapses, especially in poorly constructed buildings; notable example is the 1994 Northridge earthquake.
• Subsidence: Ground settling from structures or underground voids; significant in the 2011 Christchurch earthquake.
• Liquefaction: Saturated soils losing strength during shaking, causing buildings to sink; seen in the 1964 Niigata earthquake.
• Tsunami: Generated by underwater earthquakes, capable of extensive flooding; e.g., the 2004 Indian Ocean tsunami.

Volcanic Eruptions: Causes and Effects

• Occur when magma surfaces, creating hazards like tephra, lahars, pyroclastic flows, and lava flows.
• Tephra: Solid material from eruptions affecting air quality and agriculture; significant ashfall noted during the 1980 Mount St. Helens eruption.
• Lahar: Rapid mudflows of volcanic debris, e.g., the 1985 Nevado del Ruiz eruption.
• Pyroclastic Flow: Fast-moving and extremely hot; e.g., the 1902 eruption of Mount Pelée.
• Lava Flow: Slow-moving molten rock, destructive to infrastructure; observed in the 2018 Kilauea eruption.

Landslides: Causes and Effects

• Involves movement of rock or soil due to triggers like erosion, groundwater shifts, or seismic activity.
• Human activities such as deforestation can exacerbate landslide risks.
• Identifying hazardous areas through maps aids in disaster planning and management.

Coping with Geological Hazards

• For earthquakes: practice drills, prepare emergency kits, secure household items.
• For volcanic eruptions: plan evacuation routes, stay updated on volcanic activities, use protective gear during ashfall.
• For landslides: avoid building near slopes, use vegetation for erosion control, construct supportive structures.

Hydrometeorological Hazards

• Tropical Cyclones: Characterized by heat, low pressure, and heavy rains, leading to severe weather impacts.
• Monsoons: Seasonal winds causing heavy rainfall; distinct patterns in the Amihan (cool) and Habagat (wet) seasons.
• Tornadoes and Waterspouts: Violent winds causing severe destruction; capable of rapid formation and high wind speeds.

Coastal Hazards

• Coastal Erosion: Sediment movement caused by natural forces; leads to loss of coastal land and infrastructure.
• Submersion: Coastal areas submerging from rising sea levels; disrupts communities and ecosystems.
• Saltwater Intrusion: Seawater encroaching freshwater aquifers; threatens drinking water supplies.

Mitigation Strategies for Coastal Hazards

• Avoiding coastal construction, utilizing beach nourishment, and protecting shorelines with vegetation and engineered structures.

Conclusion

• Awareness and preparedness are vital for combating natural hazards.
• Proactive measures and community planning can significantly reduce risk and impact.