Whenever there's a series of destructive or notable earthquakes, scientists get asked the same question: are earthquakes becoming more frequent?
Authors
- Meghan S. Miller
Professor of Geophysics, Australian National University
- Allen Husker
Research Professor of Geophysics, California Institute of Technology
Over the past three months, multiple large earthquakes have occurred near population centres around the world, resulting in devastating impacts to people and infrastructure:
- Philippines (magnitude 7.8)
- Indonesia (M7.7)
- Venezuela (M7.5 and M7.2)
- Colombia (M7.4)
- Japan (M6.8).
In addition, there have been moderate-sized earthquakes on Hawai'i Island (M6.0) and Granada, Spain (M5.2) that have caused minor to moderate damage.
Is this unusual? To answer that question, we need to look at the data.
Occurrence rates
Earth is a dynamic planet and there are always earthquakes occurring somewhere. Most are too small or too far away to feel and go unnoticed by most people. However, there is a large earthquake somewhere (larger than M6.5) about every eight days on average.
This means there are usually around 46 earthquakes of magnitude 6.5 or greater each year.
As of August 21, there have been 26 earthquakes of M6.5 or more in 2026, shown as yellow dots in the global map above.
Statistically, the number of M6.5 or larger earthquakes so far this year is on track to be slightly fewer than average, as well as slightly below the annual frequency over the past 40 years, which is shown by the dashed line in this chart.
Tectonic setting
Earthquakes are primarily clustered along tectonic plate boundaries and are caused by the motion of these plates.
These regions have higher seismic hazard , such as near the well-known San Andreas Fault in California, the Alpine Fault in New Zealand, the southern Caribbean and also around the edge of the Pacific plate, the so-called Ring of Fire, where volcanoes are another geohazard .
To improve our understanding of earthquakes and their hazards, we monitor and record earthquakes globally, but also strategically install sensitive instruments in regions that are seismically active.
Over the past few decades the data from these instruments have dramatically increased, while new technologies and methodologies have been developed to learn more about earthquakes.
We have more data to better detect and locate earthquakes, but there are not more events. We know this because the average number of large earthquakes in our catalogues remains constant. Scientists have been able to catalogue the largest earthquakes for a very long time.
So why does it seem like there are more large earthquakes?
Large earthquakes happen often, but most of them don't occur near major population centres, and so pass unnoticed by most people.
The recent earthquakes are not unusual in number; they are notable because they have impacted people and communities. However, even the number of earthquakes that cause a lot of destruction remains fairly stable, as you can see below.
Nonetheless, the terrible destruction and devastating human impact the quakes have caused means they have been extensively covered by news media. This combination of impact, visibility and recency can trigger mental biases that can make it seem as if earthquakes (or other risks) are increasing.
Two of these biases are recency bias and frequency illusion. Recency bias happens when we place more importance on recent events than older information. The frequency illusion, also known as the Baader-Meinhof phenomenon , occurs when you notice a specific phenomenon more frequently after becoming aware of it.
So when several destructive earthquakes dominate the news cycle, it can seem as if earthquakes are increasing, even when the long-term data show otherwise.
In reality, only a handful of the 26 earthquakes above M6.5 this year have been mentioned in the news. Additionally, earthquakes in the western hemisphere tend to end up in news cycles in the western hemisphere, and vice versa.
We should still be prepared
Although there's no evidence the number of destructive earthquakes is increasing, the recent quakes should serve as a reminder that people living in earthquake-prone areas need to be prepared.
Preparedness is something both governments and individual people can do. Understanding seismic hazards and where they occur, ensuring seismically resilient design and construction, and creating an "earthquake-ready" public can help reduce the risk from earthquakes and keep these natural hazards from becoming disasters.
For those living in New Zealand, the AF8 program includes scientific modelling, coordinated response planning and community engagement, designed to build resilience when the next Alpine Fault earthquake happens. Similarly for those in California there are additional resources and information for earthquake preparedness .
Depending on where you live in the world, there are many resources that explain how to prepare .
The authors would like to acknowledge Wendy Bohon , Branch Chief of Seismic Hazards & Earthquake Engineering for the California Geological Survey, who contributed to this article.
Meghan S. Miller receives funding from the Australian Research Council and from National Collaborative Research Infrastructure Strategy (NCRIS) in her role as Program Director of AuScope Earth Imaging.
Allen Husker receives funding from the United States Geological Survey and the California Office of Emergency Services in his role as head of the Southern California Seismic Network.
