An earthquake is the sudden, rapid movement of a block of Earth’s crust along a fault plane, generating seismic waves that travel through the planet. This natural phenomenon is constant, yet many people perceive that the frequency of these events is rising significantly. The sense that “so many” earthquakes are occurring involves a complex interplay of natural forces, vastly improved technology, and global communication. To understand this feeling of increased seismic activity, we must consider the human lens through which these events are now viewed and recorded.
The Geological Forces
Earthquakes are fundamentally a product of plate tectonics, the process by which the Earth’s outermost layer, the lithosphere, is divided into large, constantly moving plates. These plates grind against, pull apart from, or slide beneath one another at their boundaries. This motion is not smooth, causing immense mechanical stress to accumulate in the crustal rocks over decades or centuries.
The energy builds up along geologic fractures known as fault lines, where friction locks the rocks in place. When the accumulated stress exceeds the rock’s strength, the fault suddenly slips, releasing stored energy as seismic waves. This sudden release is the earthquake, and the size of the rupture determines the magnitude. This geological engine has operated consistently for billions of years, providing the baseline rate for all natural seismicity.
Increased Detection and Reporting
While the Earth’s geological forces are constant, the human ability to detect and report seismic events has changed dramatically, influencing the perception of rising frequency. Data indicate that the global rate of major earthquakes (magnitude 7.0 or greater) has remained relatively stable over the last century. The actual increase has occurred in the number of smaller events that are detected and logged.
Technological advancements in global seismic networks are the primary reason for this jump in recorded events. Since the 1970s, the expansion of networks like the Global Seismographic Network (GSN) has vastly increased the number of monitoring stations worldwide. Modern digital seismographs are exponentially more sensitive than older analog models. This allows scientists to routinely detect minor earthquakes in the magnitude 2.0 to 4.0 range that previously went unnoticed, especially in remote regions.
This expanded detection capability creates a much larger catalog of events, even if the total energy released remains unchanged. The growth of global communication and the 24/7 news cycle amplifies the visibility of every recorded tremor. Instantaneous news reports and social media ensure that an earthquake occurring anywhere is reported nearly in real-time, contributing to the feeling that seismic activity is relentless.
The rapid growth of urban centers near geologically active fault systems also contributes to a heightened sense of frequency. As metropolitan areas like Istanbul, Los Angeles, and Mexico City grow, more people are exposed to the shaking from a standard seismic event. This increased exposure and the resulting higher potential for damage lead to greater media attention and public awareness, reinforcing the perception that earthquakes are happening everywhere.
Earthquakes Triggered by Human Activity
A distinct category of events known as induced earthquakes contributes to the overall count of registered seismic activity, particularly in regions that were previously quiet. These events are not caused by natural tectonic movement, but are triggered by specific industrial practices that alter the stress balance deep underground. The most significant cause of induced seismicity in certain areas is the deep-well injection of wastewater, a common practice in oil and gas production.
This wastewater, which can be saline water or flowback fluid from hydraulic fracturing, is pumped into deep geological formations for disposal. The fluid enters fractured rock layers and increases the pore pressure within the rock structure. This elevated pressure acts as a lubricant, reducing the friction holding existing, stressed faults in place. If the pressure exceeds a certain threshold, the fault can slip, triggering an earthquake.
Other human activities can also induce earthquakes through similar mechanisms of fluid pressure change or crustal stress alteration. The impoundment of water behind large dams, called reservoir impoundment, can add significant weight to the crust and force water into underlying fractures. Projects involving fluid injection or extraction for geothermal energy production or carbon capture and storage have also been linked to induced seismicity. These human-triggered events, though often smaller, add measurably to the total number of earthquakes recorded each year, especially where they were historically uncommon.