Quakes and Typhoons: What's Up with Mother Nature?

Andrea Thompson, livescience.com 11 Aug 09;

It may seem like Mother Nature is pulling out all the weapons in her arsenal, after a spate of earthquakes and cyclones struck Asia in recent days, but the fact that these events coincided is just that - a coincidence.

Typhoon Morakot was the first to strike, slamming into Taiwan Sunday and causing disastrous mudslides with its torrential rains. Scores are feared to have died in the maelstrom.

While the Taiwanese were lashed by the storm's wind and rain, a 7.1-magnitude earthquake rumbled off the Japan coast, also on Sunday. On Tuesday, Japan was struck again by a magnitude 6.5 earthquake that triggered a small tsunami and caused buildings to sway in Tokyo, some 90 miles away, according to news reports. While the Earth trembled, the country was also seeing rain from Typhoon Etau.

Minutes before, another earthquake had ruptured in the Indian Ocean on Tuesday, north of India's Andaman Islands. The United States Geological Survey (USGS) put the magnitude of that temblor at 7.6.

The events have little to nothing to do with each other, except that they are happening in an earthquake-prone region of the world that is in the middle of its tropical cyclone season.

Stormy links

The western Pacific typhoon season lasts from about mid-May to November, about the same time as the Atlantic hurricane season (June 1 to Nov. 30). (Hurricanes and typhoons are the same phenomenon, collectively known as tropical cyclones. They just carry different names, because they occur over different ocean basins.)

While the Pacific typhoon season has been busy, no tropical storms or hurricanes have yet sprouted in the Atlantic. This is because of events a world away -the El Nino that has developed in the eastern Pacific. El Nino puts energy high into the atmosphere that tends to promote cyclone activity in the Pacific. That energy moves across the Americas, over the Atlantic, and tends to stifle hurricane formation in the Atlantic.

"That has worldwide effects," said Dennis Feltgen, a spokesman for the National Hurricane Center in Miami, referring to El Nino.

The Atlantic hurricane activity does seem to be picking up though, with the development of the second tropical depression of the season (tropical depressions have less intense winds than tropical storms, which in turn are less intense than hurricanes). Tropical Depression 2 seems to be on track to develop into Tropical Storm Ana, which will be the first named Atlantic storm of the season.

"We're seeing more activity now than we've seen all season," Feltgen told LiveScience.

The busiest months of the Atlantic season are typically August and September.

Shaky links

While the cyclone and earthquake activity in Asia aren't linked, there was initially some thought that the earthquake activity might have been.

The earthquake in Japan on Tuesday happened a mere 11 minutes and 29 seconds after the Andaman Islands quake in the India Ocean.

"They were very close in time," said Paul Caruso, a geophysicist with the USGS.

Scientists looked to see if the seismic waves from the Andaman quake might have triggered the Japan quake, but saw that the waves from the first quake arrived too early to have caused the second one, about 8 minutes and 40 seconds after the Andaman quake.

"We don't think they're linked at all," Caruso told LiveScience.

Neither of the Japanese quakes was linked either, with the Sunday temblor happening very deep in the ground, and the Tuesday earthquake occurring farther north and at a more shallow depth, Caruso said.

While aftershocks have shaken the regions hit by earthquakes, whether or not more strong quakes will occur can't be predicted.