After the huge earthquake in Japan on March 11th 2011 (magnitude 9.0), many people in the eastern area of Japan close to the epicenter felt dizziness, as if they were rocking at a time when no aftershocks were actually occurring. There are a few reports about dizziness after major earthquakes in the world, but there has been no study so far with analysis of large numbers of cases of earthquake sickness. We conducted an epidemical clinical study and called those symptoms “post earthquake dizziness syndrome; PEDS.”
Affected subjects became aware of the rocking feeling within a minute especially when indoors and seated. A significant difference was found with respect to gender, with a prevalence of females, and with the people who were prone to suffer from motion sickness. Otherwise, there was no relationship with case histories of vertigo-related diseases. On the other hand, anxiety and social stress from the disaster seemed to be contributory factors.
The underlying mechanism is associated with stimuli to the vestibular and equilibrium balance systems. Emotional disorders such as post-traumatic stress disorder (PTSD) were added to the etiology. For the prevention and treatment, maintaining fitness in daily life and avoiding anxiety caused by reports in the media seemed to be important. Physiotherapy and medication also proved important to prevent symptoms from getting worse.