By Laurel Cleary | Updated March 24, 2022
The Earth is a mosaic of tectonic plates that drift and collide, releasing seismic energy when one yields to another. This energy propagates as seismic waves, which can reshape the land, alter groundwater flow, and trigger tsunamis that inundate coastlines. Understanding these processes helps scientists and communities prepare for and mitigate earthquake impacts.
Most human casualties arise from building collapse, driven by the interaction of body and surface waves. As the waves travel through the ground, they impose dynamic forces on foundations, stressing walls and joints. Structures not designed to resist these loads buckle or fail.
Earthquakes can initiate various landslides. The most frequent are rockfalls on steep slopes, followed by soil avalanches on otherwise stable, fine‑grained slopes. Subaqueous landslides occur in deltas, damaging port facilities—as occurred in Seward, Alaska, in 1964.
In saturated sandy soils, seismic shaking turns the ground into a fluid‑like state, similar to quicksand. Liquefaction manifests in several forms:
When the supporting soil liquefies, structures lose bearing capacity, settling or toppling.
Earthquakes alter groundwater dynamics by expanding or contracting aquifers, sometimes temporarily and sometimes permanently. Fault movement can offset stream channels, creating sag ponds along strike‑slip faults. The most dramatic hydrospheric response is a tsunami—an ocean‑floor displacement that generates waves several feet high at sea level but can swell to devastating heights as they approach shallow coastal waters. Lakes can experience a smaller‑scale analogue called a seiche.
Large earthquakes can raise mountain peaks by inches to a few feet. Fault movement produces scarps—steep ridges—while repeated events erode fault zones into valleys. Faults also influence groundwater distribution, forming ponds or springs, and surface strike‑slip faults appear as long, shallow disruptions known as mole tracks.
By integrating geological, hydrological, and engineering perspectives, scientists can better predict and mitigate the multifaceted effects of earthquakes on our planet’s living systems.
