Explain why densely populated coastal cities near subduction zones face high tsunami and earthquake risk, and how urban planning can mitigate this.

• A. Coastal cities are immune due to infrastructure.
• B. Urban planning cannot mitigate hazards.
• C. High exposure to intense shaking and potential tsunamis; mitigation includes strict building codes, tsunami hazard zoning, early warning, evacuation planning, and land-use controls.
• D. Tsunami risk only affects unpopulated areas.

Answer: (C)

Exposure and vulnerability are the key ideas here. Subduction zones produce large, sometimes megathrust earthquakes, and the nearby coastline means intense shaking can affect dense urban areas with lots of buildings, lifelines, and people. Tsunami waves can arrive quickly after a quake, flood low-lying coastlines, and disrupt infrastructure, transportation, and emergency response. When many people and critical facilities are concentrated in these zones, the potential damage and casualties rise sharply.

Urban planning helps reduce both exposure and vulnerability. Strict building codes ensure structures can withstand strong ground shaking, lowering collapse risk and injuries. Tsunami hazard zoning guides where development can occur and often requires elevated or flood-proof designs in risk areas, reducing inundation damage. Early warning systems paired with clear evacuation planning give people precious seconds to reach higher ground or safe zones, saving lives. Land-use controls help preserve evacuation routes, create safe assembly areas, and limit construction in the most dangerous spots, making rapid, organized responses more feasible. Together, these measures shift the balance from high-risk exposure to a more resilient coastal city.