How are long-term and short-term earthquake predictions made? What is the basis for determining a recurrence interval, and what does a recurrence interval mean? What is an earthquake early warning system? (H)

Long-term earthquake predictions estimate the probability of an earthquake occurring in a specific region within several decades or more, based on geological history and past patterns. Short-term predictions estimate the probability of an earthquake within days, weeks, or months, using seismic activity and other data. A recurrence interval is the average time between two successive earthquakes on a fault or in a region, determined by analyzing geological evidence left by past earthquakes. It represents the average time for energy buildup and release through earthquakes. An earthquake early warning system uses sensors to detect the initial P-waves emitted by an earthquake, triggering an alarm to alert people in the affected area, providing time to take protective actions before more destructive S-waves arrive.