Which of the following is a primary effect?

• A. Ground shaking
• B. Landslide
• C. Deaths
• D. Road/bridge destruction

Answer: (D)

Primary effects are the direct results of the earthquake’s energy. The ground shaking itself is the basic manifestation of that energy, and it immediately stresses and damages structures. The destruction of roads and bridges happens because that same strong ground motion directly damages and collapses transportation infrastructure. It’s a direct, immediate consequence of the shaking, making it a primary effect. Landslides are often triggered by the shaking but are considered secondary effects, since they arise from the ground movement rather than being the initial energy itself. Deaths are a downstream outcome of the damage and hazards that follow shaking, not a direct physical effect. So, road and bridge destruction best represents a primary effect because it is the immediate damage caused by the earthquake’s ground motion.