The Japan disaster had a devastating immediate effect on tens of thousands of people but the true psychological impact will be felt "for some time to come", a psychology expert at Queen Mary, University of London has said.
Magda Osman, Psychology Lecturer at the University, said the psychological impact of natural disasters such as the Japan earthquake could be revealed in the way people inherently respond to unpredictable situations.
"A disaster like the Japan earthquake has such wide-ranging implications, especially on the psychological well-being of those affected," Osman said.
"After a disaster, typically small communities become incredibly co-operative and pull together to help each other and start the rebuilding process. There's an immediate response where people start to take control of the situation, begin to deal with it and assess and respond to the devastation around them.
"The problem is that we aren't very good at calculating the long-term effects of disasters. After about two months of re-building and cleaning up we tend to experience a second major slump when we realise the full severity of the situation in the longer term. This is what we need to be wary of because this triggers severe depression," she said.
Osman said as soon as there is a disaster, there is often a rapid increase of mental health problems in the people who have been affected. This is because natural disasters threaten our sense of control in the world.
"Our sense of control is like a mental engine, it's like an adaptive driving force that helps us stay motivated. When bad, unpredictable events happen we don't feel we have any effect over anything and this is when we start to lose self esteem," she added.