Hi friends hope you all are fine According to my opinion Whenever a disaster or tragedies occur in a particular country, the investors in that country's stock markets start withdrawing their capital. Due to this they sell their shares they purchased quite some time back. Selling of stocks make the country's Stock indices to fall down rapidly. Due to this selling and withdrawing of funds, the value of the currency they are buying back by selling shares rises quickly. That is what happens initially just after the disaster.
On the international level, just after 2 or 3 days of the disaster, Big banks and organizations decide that the disaster destroyed a particular country strongly and needs some recovery. Due to this statement, people all around the world start selling that currency and it becomes weaker and weaker lately.Best wishes. Thanx to all of you