While predicting the next big earthquake is probably impossibility, there's still a lot we can learn about what causes severe earthquakes. We've now identified the trigger for some of the most destructive recent earthquakes, including the 2007 quake in Haiti.
Some earthquakes, it seems, are at least partially caused by tropical cyclones, known as hurricanes in the Atlantic and typhoons in the Pacific. While not all earthquakes can be traced back to these super-storms - it doesn't explain Japan's Tōhoku earthquake earlier this year, for instance - this newly discovered link could help us pinpoint areas that are most at risk for destructive earthquakes in the future.
University of Miami researcher Shimon Wdowinski found that in three separate instances in the last fifty years where extremely wet typhoons that passed over the Taiwanese mountains were followed within four years by major earthquakes in those same areas. Similarly, the 7.0 magnitude earthquake that hit Haiti in 2010 came a year and a half after two hurricanes and two tropical storms drenched the country's mountains within a space of just 25 days.
The reason why all this matters is that the fault areas are located in the mountainous regions of Haiti and Taiwan. When the cyclones pass through, they dislodge rocks and start landslides, washing huge amounts of material downstream. This reduces the surface load above the fault, which makes it easier for the fault lines to become active. Wdowinski explains:
"Very wet rain events are the trigger. The heavy rain induces thousands of landslides and severe erosion, which removes ground material from the Earth's surface, releasing the stress load and encouraging movement along faults. The reduced load unclamp the faults, which can promote an earthquake."
Right now, the link has only been demonstrated for Haiti and Taiwan, though Wdowinski hopes to expand his research by looking for similar correlations in Japan and the Philippines. Whatever the case, this doesn't explain every earthquake - just those that happen on inclined faults, where there's lots of vertical movement - and this likely isn't the only factor behind why these particular earthquakes occur.
Still, if the link holds up, it could give us a vital new tool in preparing for potentially disastrous earthquakes. Hurricanes and typhoons might not just be the potential triggers for major earthquakes down the road - they could also now serve as an early warning system, even if they are admittedly rather frustratingly inexact.