A seismologist models earthquake wave decay: the amplitude of a seismic wave decreases by 40% every 10 kilometers it travels. If the initial amplitude is 150 units, what is the amplitude after traveling 30 kilometers?

Wed, 06 May 2026 15:31:33 +0000

Modeling Earthquake Wave Decay: How Amplitude Slows with Distance Understanding earthquake wave propagation is essential for predicting ground motion and improving seismic safety. A key aspect of this is how seismic wave amplitude diminishes as waves travel through Earth’s crust. Recent modeling highlights a clear and predictable decay pattern: seismic wave amplitude decreases by 40% every 10 kilometers. This exponential decay model helps scientists estimate how strong ground shaking will be at different distances from an earthquake’s epicenter. ### The Decay Pattern Explained If a seismic wave starts with an initial amplitude of 150 units, each 10-kilometer interval decays the wave’s amplitude by 40%. This means only 60% of the wave’s energy remains after every 10 km. Mathematically, this represents a multiplicative decay rather than an additive drop.