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Has there been a change in frequency in earthquakes and volcanic eruptions?


It's been a week since a series of powerful earthquakes shook Japan's west coast. More than 125 people died, and more than 100 people are still missing. The quake came less than a month after a volcanic eruption pushed molten lava through parts of southwestern Iceland.


PAMELA BROWN: Lava and smoke spewing into the air. It is not unexpected after several weeks of seismic activity in the area.


Yeah. From Iceland to Italy to the Philippines to Afghanistan to Chile to Indonesia, we heard a lot about seismic activity in the past year. Was there really more?

CHUCK BAILEY: No, there's not really been a change in frequency in earthquakes and/or volcanic eruptions.

MARTIN: The president of the Geological Society of America, Chuck Bailey, says Iceland and Japan were spectacular, photogenic events. They appeared all over social media, and that made it feel like more is going on.

BAILEY: But if you step back out and looked at it over the course of a year or a year and a half, my suspicion is that the seismicity, as well as the number of volcanoes that are erupting, will effectively end up being about on pace with what normally our planet does.

INSKEEP: Seismicity.

Magnus Tumi Gudmundsson is a geophysics professor at the University of Iceland and also an Icelander.

MAGNUS TUMI GUDMUNDSSON: Over the last years or decades, we are seeing the same trend as we have seen over the past centuries.

MARTIN: Which means, according to the National Earthquake Information Center, about 20,000 quakes worldwide each year, with no evidence that the frequency of seismic activity has changed.

GUDMUNDSSON: The biggest eruptions memory in the United States was the Mount St. Helens eruption of 1980. And then we had Pinatubo eruption in 1991. And then we had the rather spectacular Hunga Tonga event. These events do not happen very frequently.

INSKEEP: What has changed, according to the experts, is the increase in climate disasters fueled by human-caused climate change. One of those experts is volcanologist Marco Brenna at the University of Otago in New Zealand.

MARCO BRENNA: The increasing occurrence of these weather events might be subconsciously increasing natural disasters like earthquakes and volcanoes, but it's totally different systems.

MARTIN: So while seismic activity can affect weather and generate tsunamis, there is a risk of conflating seismic activity with the general increase in climate events.

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