Ecology
Typhoons and hurricanes can contribute to large earthquakes in tropical seismically hazardous regions, scientists say.
Due to heavy rains and landslides, hurricanes can change the weight of rock in dangerous areas, causing pressure in certain places, resulting in earthquakes. Stressed rock that is under pressure is more likely to deform within a few years after severe tropical cyclones.
The 2010 earthquakes in Haiti (7) and Kaohsiung, Taiwan, in the same year (6.4) followed such hurricanes, as scientists led by Shimon Wdowinski have found , Professor of Marine Geology and Geography from the University of Miami.
“The cyclone itself is a disaster because it brings floods that cause landslides, followed by earthquakes,” Wdowinsky said.
The chain reaction of natural disasters
Wdowinsky and his colleagues became interested in this issue when they noticed that tropical cyclones occurred shortly before the terrible earthquakes in Haiti and Taiwan. In the case of the 2008 Taiwan earthquake, Typhoon Morakot was observed in the area, which caused about 292 centimeters of rain over 5 days. Haiti experienced severe seasonal hurricanes Fey, Gustav, Hana and Ik in 2008, which brought a lot of trouble.
The researchers wanted to find out if this was just a coincidence or if earthquakes had something to do with hurricanes. They began exploring areas in Taiwan where earthquakes and hurricanes have experienced numerous earthquakes and hurricanes over the past 50 years.
Paying attention only to typhoons and hurricanes that brought rains that could cause erosion, and excluding earthquakes that did not occur before such cataclysms, researchers It was determined that 85 per cent of the time, large earthquakes of magnitude 6 or higher occurred within a few years after very large rain storms.
Even minor earthquakes have also followed such hurricanes. In 35 per cent of cases, earthquakes of magnitude up to 5 occurred within the next 4 years after the hurricanes. This is twice as much as expected.
A matter of time
Past studies have shown that too low pressure caused by hurricanes can trigger earthquakes in dangerous areas within a short time, but in this case completely different mechanisms are involved. These areas are already tectonically active, and the deformation builds up stress when the rock masses begin to move. As a result, this leads to fractures and earthquakes occur.
During typhoons and hurricanes with heavy rains, streams of water cause landslides in mountainous areas. Additional showers in the following months further undermine the rock, resulting in displacements when the elastic strength of the rocks is deformed.
Scientists say that such earthquakes do not differ in strength from ordinary ones, but tropical cyclones may tell scientists that this seismically dangerous area will soon (several years) there'll be an earthquake. Scientists also reported that the main culprits of earthquakes in these regions are not hurricanes with rain. They only contribute to the conclusion that earthquakes in this area are very likely.