Can an active hurricane season lead to an increase in earthquakes?

With Mexico still reeling from devastating earthquakes and aftershocks that occurred around the time that major hurricanes plowed through the Atlantic Ocean, Caribbean Sea and Gulf of Mexico, some might wonder whether the two natural disasters are somehow related.

As Irma battered Caribbean islands with heavy rainfall and powerful winds, an 8.1 magnitude earthquake struck Mexico’s southern coast on Sept. 7. Meanwhile, Katia also lashed the country’s eastern coast.

Weeks later, Mexico was again rattled by powerful 7.1 and 6.1 magnitude earthquakes as Maria pounded Puerto Rico and several other islands in the Caribbean Sea.

The earthquakes have killed more than 320 people.

While it’s not uncommon for tropical cyclones to occur in seismically active regions, research is limited on whether the two events are linked or if one event directly causes the occurrence of the other.

However, there is some evidence that some effects of a hurricane can contribute to seismic activity.

“Changes in air pressure, even extreme ones due to hurricanes, can generate seismic waves, but those seismic waves are typically very much smaller in magnitude than the seismic waves from big earthquakes,” said Dr. Raymond Russo, geophysics professor at the University of Florida.

Researchers from the University of Miami and Florida International University also found that significant rain events, such as hurricanes, could possibly lead to earthquakes.

The 2011 study analyzed information from magnitude 6-and-above earthquakes that occurred in Haiti and Taiwan and discovered that major earthquakes tended to happen within four years of extremely wet tropical cyclone seasons.

According to Dr. Shimon Wdowinski, the research associate professor who led the study, severe erosion and landslides can occur after heavy rainfall, especially in mountainous regions.

“When the erosion removes the material from the mountains, it changes the crust beneath the mountains and reduces what we call normal stressing ability of the crust to hold on faults,” Wdowinski said.

This activity can promote an earthquake, he said.

In 2010, Haiti endured a 7 magnitude earthquake a year and a half after being pummeled with heavy rain from two hurricanes and two tropical storms in a short timeframe.

“If you go back and look at when Haiti had some of their major hurricanes, it’s not the hurricanes that caused the earthquake, it’s the excessive rainfall,” said Bill Kirk, chief executive officer of Weather Trends International.

“You’re adding heavy weight that is normally not there on a given geography,” Kirk said.

When excessive rainwater seeps down into the Earth’s fault lines and into the crevices, it could take weeks or months for the water and added weight to impact those faults, Kirk added.

“You could argue that the rain in earthquake-prone areas is kind of like oil – it helps slip up the fault lines where the two could actually slip, and that’s what causes the earthquakes: fault lines slipping and merging against each other,” he said.

Kirk also said that due to the large distance between Maria, Irma and the earthquakes in Mexico, the events were not related.

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