KUMAMOTO--An increasing number of residents here are complaining of “earthquake sickness," caused by the prolonged aftershocks from the major temblors that started in April in Kumamoto Prefecture.
Experts say the inconvenience of prolonged stays in shelters and cars after the mid-April quakes are a major contributor to the development of the syndrome.
Also known as post-earthquake dizziness syndrome, earthquake sickness is a condition in which an individual feels a false sensation as if they are experiencing an actual tremor.
The human brain maintains the body’s balance by processing information from the semicircular canals of the inner ear, the eyes and from sensations from the arms and legs.
Although the cause of earthquake sickness is not fully understood, researchers believe it develops when the part of the brain in charge of maintaining body equilibrium receives extra stress from frequent earthquakes.
Experts from Kumamoto University and Hidetake Matsuyoshi, a doctor specializing in balance disorders and the director of the Matsubase Clinic in Uki, Kumamoto Prefecture, examined 214 individuals, both new and existing patients, complaining of dizziness during a one-month period beginning April 19.
Of those, 108 were diagnosed with earthquake sickness. Female patients counted for 80 percent of those diagnosed.
Out of the 108, 81 were living in cars or shelters, and the remaining 27 were living in their homes.
Results of physiological tests showed many have been feeling stress and anxiety, with 20 to 50 percent believed to be suffering from neurosis and depression.
Matsuyoshi said in addition to the long streak of earthquakes, living conditions and physiological distress have put pressure on the autonomic nervous systems of many individuals, making them more liable to develop earthquake sickness.
Post-earthquake dizziness syndrome was also experienced by many survivors of the 2011 Great East Japan Earthquake as frequent aftershocks shook large areas of Japan.
After the 2011 earthquake, a survey was conducted by the Nihon University School of Medicine on about 3,000 people, including children, living in Tokyo and Chiba Prefecture. The survey revealed that about 80 to 90 percent of adults and 50 to 70 percent of children experienced symptoms of earthquake sickness.
The condition usually subsides as seismic activity subsides.
However, Kumamoto residents may have to deal with it for some time as the ground beneath the city and prefecture continues to percolate and shows few signs of settling down. More than 1,600 earthquakes with an intensity of at least 1 on the Japanese scale of 7 have hit Kyushu since the seismic activity started on April 14.
“You are more prone to experience the symptoms when you are sitting inside a building,” Matsuyoshi said. “For those still living in shelters, it is important to relax by walking and exercising.”
http://www.asahi.com/ajw/articles/AJ201606190010.html
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