Which country had the most advanced earthquake warning system in the world at the time the article was written?

• A. Japan
• B. United States
• C. Mexico
• D. China

Answer: (A)

The key idea is how quickly and reliably a system can detect an earthquake and warn people and infrastructure to reduce damage and injuries.

Japan stands out because it built a mature, nationwide earthquake early warning network with dense sensor coverage and fast real-time processing. Seismographs spread across the country detect the initial P-waves, which travel faster than the damaging S-waves, and within seconds the system estimates the likely shaking and broadcasts warnings. Those alerts are integrated with automated actions—such as slowing or stopping trains, shutting off gas valves, and notifying schools and hospitals—which can drastically cut risk. The combination of broad coverage, rapid analysis, and widespread, practical responses across public and private sectors makes Japan’s system the most advanced among the options.

Other countries have notable efforts, but at that time their systems were less extensive or mature, so they didn’t match Japan’s level of readiness and integration.