The global frequency of significant earthquakes has increased in recent decades

What's this about?

People disagree about whether big earthquakes now happen more often around the world. Some years have many terrible quakes, but long-term records tell a different story.

What supporters say

• Some recent years had many strong earthquakes, which can make a rise seem clear.
• A big quake often brings many aftershocks, or smaller quakes that follow the first one.
• News reports can make several disasters in a short time feel like one global trend.
• Mining, dams, and fluid pumping can cause more quakes in some local areas.

What critics say

• Records of large earthquakes do not show a steady recent rise across the whole world.
• Groups of major quakes can happen by chance, even when the usual rate stays the same.
• Comparing one busy year with one quiet year does not show a long-term change.
• Local human-caused quakes do not prove that natural global earthquakes have increased.

The bottom line

The best evidence does not show that major earthquakes now happen more often worldwide. We do see busy periods and local rises, but they do not prove a lasting global rise.

The claim that significant earthquakes have become more frequent worldwide in recent decades is understandable: recent years have included dramatic clusters of destructive quakes and high annual totals in some records. But the best available evidence indicates that these patterns do not show a sustained rise in the global rate of major earthquakes.

The case for

There have been conspicuous periods of high earthquake activity in recent decades. Public earthquake catalogs and statistical summaries can show elevated counts in certain magnitude ranges, while several recent sequences have included multiple damaging events. Compared with quieter years, those episodes can make it appear that the world is experiencing more earthquakes than before. 1

That impression is especially powerful when annual totals are compared side by side, or when a major earthquake is followed by a long sequence of aftershocks. A short span containing several large, widely reported disasters can feel like evidence of a new global pattern.

There are also narrower situations in which earthquake activity can genuinely rise. Human activities including fluid injection, mining, reservoir construction and geothermal operations can trigger earthquakes in particular places. Such induced seismicity may increase locally, but it is distinct from a worldwide increase in natural tectonic earthquakes.

The central complication is the word “significant.” It could refer to small but newly detected quakes, major global tectonic events, or local earthquakes linked to industrial activity. Evidence about one of those categories cannot automatically be used to support a claim about the others.

The case against

The strongest evidence concerns large earthquakes—the events most likely to be considered significant in a global sense—and it does not find a recent worldwide increase. A study published in *PNAS* concluded that the apparent clustering of major earthquakes is consistent with chance, rather than evidence that the underlying global rate or risk has risen (see Figure 2). 2 The U.S. Geological Survey has likewise said it sees no evidence of an increased global rate of major earthquakes.

Short-term bursts are not unusual in a random process. Major quakes can be followed by aftershocks, and unrelated earthquakes can happen close together by chance. These patterns can temporarily lift annual totals without changing the long-run average. USGS long-term statistics describe year-to-year variation as normal.

Recorded earthquake numbers are also a poor guide to physical trends unless the records are comparable across time. Monitoring networks, instruments and communications have improved sharply, meaning that modern systems detect and report many smaller earthquakes that earlier systems would have missed. The USGS says this improved observation explains much of the apparent rise in reported earthquakes. 3

Older catalogs are uneven in other ways as well. Network coverage, location accuracy, magnitude measurements and reporting practices have changed over time. That makes simple comparisons of raw counts across decades unreliable. Researchers have created harmonized databases, including ISC-GEM, specifically to reduce these historical biases when studying long-term patterns in large earthquakes (see Figure 3). 4

These limitations matter most for smaller events, whose recorded frequency has risen as detection has improved. For large earthquakes, however, the available analyses still do not show a robust recent global rise.

The bottom line

The evidence strongly weighs against the broad claim that significant earthquakes have become more frequent worldwide in recent decades. Confidence is high because major-earthquake research, USGS assessments and studies of earthquake-record quality point in the same direction: apparent increases can be explained by chance clustering, aftershock sequences and better monitoring, rather than a higher global earthquake rate.

The claim could be true if it were made much more narrowly—for example, about a particular region, magnitude range, short-lived cluster or locally induced earthquakes. But those cases do not establish a general global increase in significant natural earthquakes.