Why do earthquakes occur and what does science reveal about their causes, measurement, and unpredictability? A clear, news-style analysis.
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| Comprehensive news-style analysis of earthquake causes, seismic science, and why prediction remains impossible. Image: CH |
Science Desk — November 21, 2025:
Earthquakes remain among the most powerful and disruptive natural events, reshaping landscapes, damaging infrastructure, and challenging the scientific community’s ability to forecast them. While researchers understand the mechanics behind earthquakes better than ever, the exact timing of such events remains impossible to predict.
Earthquakes begin when two sections of the Earth’s crust, locked together by friction, suddenly slip along a fault plane. This abrupt movement releases accumulated stress from a point deep underground known as the hypocenter. Directly above it lies the epicenter, the location where the strongest shaking is usually felt. Major earthquakes often follow a recognizable sequence. Smaller tremors known as foreshocks may occur in the same region before the primary rupture. The central event, the mainshock, is typically followed by days, weeks, or even months of aftershocks as the crust continues to adjust.
The deeper cause of these events lies in the structure of the Earth itself. The crust and upper mantle form a rigid outer shell composed of tectonic plates. These plates move slowly across the planet’s surface, grinding against one another, colliding, or pulling apart. Although they generally move in a steady manner, their rough edges can lock together. Pressure then builds until the strain exceeds the strength of the fault, resulting in a sudden release of energy. This moment of rupture sends seismic waves through the Earth, creating the shaking that residents feel on the surface.
The process of shaking can be understood through the movement of these waves. When the fault breaks, the stored energy expands outward in all directions, similar to ripples created when a stone is dropped into water. As the seismic waves reach the surface, they cause the ground and everything built upon it to shake. The force of these vibrations depends on the size of the rupture, the amount of slip, the depth of the earthquake, and the geological conditions of the region.
To study these events, scientists rely on seismographs, instruments designed to record ground motion. A seismograph remains partly stationary even while the ground moves, allowing the device to track the relative motion. The resulting seismogram displays lines that vary in length and intensity based on the strength of the shaking. Long, dramatic movements on the seismogram indicate a large earthquake, while shorter, smaller deviations signify weaker events. Magnitude is calculated from this data, reflecting the size of the fault rupture and the energy released. Intensity, however, varies by location, depending heavily on proximity to the epicenter and local geological conditions.
Determining the exact location of an earthquake involves careful analysis of seismic waves. P waves, which travel faster, arrive first at recording stations. S waves follow more slowly. By comparing the difference in arrival times between these two wave types, scientists can estimate how far the earthquake occurred from each seismograph. A single instrument cannot determine direction, but when three or more stations calculate their distances and draw corresponding circles on a map, the circles intersect at the epicenter. This method, known as triangulation, remains fundamental to earthquake detection worldwide.
Despite enormous advances in seismic monitoring, satellite observations, and computational modeling, scientists still cannot predict earthquakes. Fault systems behave in highly complex ways, and no consistent warning signs have been observed before major ruptures. Experts can identify regions with long-term seismic potential, such as Japan, Turkiye, Chile, India, Bangladesh, Afghanistan and California, but they cannot determine precisely when the next major event will strike.
As research continues, the scientific community remains focused on improving early warning systems, strengthening infrastructure, and increasing public preparedness. Earthquakes remind the world that the planet is constantly shifting, and while their causes are well understood, their timing remains an unresolved challenge in modern geoscience.