Amid a series of aftershocks in Kyushu after deadly earthquakes struck Kumamoto Prefecture last week, experts warn strong tremors may cause dizziness, as the March 2011 earthquake did among survivors.
To maintain a sense of balance, the human brain processes information from the skin, muscles, eyes and ears, according to Yasuyuki Nomura, a professor specializing in otolaryngology at Nihon University School of Medicine in Tokyo.
A strong tremor interferes with this normal functioning, and can have an effect long after a quake is over. In some cases, stress and anxiety triggers the memory of the shaking, leading survivors to mistakenly believe they are experiencing a quake. In his research on the phenomenon, Nomura dubs it post-earthquake dizziness syndrome, or PEDS.
Following the Tohoku quake, Nomura's team surveyed some 3,000 patients who underwent treatment at medical institutions in the Tokyo metropolitan area and Fukushima Prefecture between March and May 2011.
About 80 to 90 percent of adults and 50 to 70 percent of children had experienced sudden bouts of dizziness. In many of those cases, dizziness occurred when they were indoors and seated.
"Dizziness is less likely to happen if they are outdoors in the open rather than in a confined space indoors. Exercising (outdoors) will help ease the anxiety associated with the memory of the tremor in the brain," said Nomura.