Lightning is not supposed to strike the same place twice. Tragically, the same cannot be said of earthquakes.
The powerful quake which hit Indonesia on Monday night comes only three months after the same area was devastated by the Asian tsunami.
It is a cruel blow, which has added greatly to the terror and trepidation already felt by those who have been living in fear of another disaster.
The 8.7 magnitude earthquake was not as powerful as the one which caused the tsunami, resulting in the loss of almost 300,000 lives in 11 countries. But it ranks among the eight strongest recorded since 1900.
Nias, an island off Sumatra, has been worst hit. Early reports suggest that thousands have been killed or wounded. Buildings have been flattened.
Our hearts go out to the victims. Many of them survived the horror of the tsunami. Now they find themselves facing a new disaster.
The tragedy could, however, have been on a much greater scale. The earthquake was big enough to have caused another killer wave, possible stretching for 1,000km and hitting many of the countries still recovering from the last one.
Mercifully, that nightmare scenario did not occur this time. Some experts cannot understand why. It appears to have been a near miss.
This underlines the danger of another tsunami occurring - and the urgent need for better protective measures to be put in place.
Lessons have clearly been learned since the waves struck in December. This time, monitors in the Pacific picked up the threat and quickly passed the information to nations which were likely to be hit if there were a tsunami.
The warning was relayed to coastal areas and emergency measures taken. Government officials went on television to warn the public. Evacuations were organised in Thailand, Sri Lanka, India and Malaysia. Thousands headed for the hills. It was a big improvement on the failure to respond to the approaching tsunami in December. But the Indian Ocean is still without a fully fledged warning system. Efforts to put one in place should now be stepped up. The risk of a tsunami could not be more apparent.
The Indonesian government put out its own warning. But for people in Aceh, the area hardest hit by the tsunami, the earthquake itself was warning enough.
There have been many aftershocks since December. This one was on a different scale. Terrified people poured out of their homes and scrambled to reach higher ground. The death and devastation of the tsunami is still fresh in their memories. The widespread panic is understandable.
Nias is now in need of fresh supplies of aid. Australia and Japan have offered help. And there are many foreign aid workers already on the ground in Sumatra, helping victims recover from the tsunami.
The earthquake should make the Indonesian government think again about its plans to scale down the international relief operation.
Foreign aid workers had been due to leave Aceh last Saturday on the orders of the government. They would have left just before Monday's earthquake struck. Fortunately, the deadline had been extended by a month.
But the position of the aid agencies remains uncertain and the United Nations agency dealing with refugees has already been forced out.
Indonesia has a political agenda, especially in Aceh where it has been fighting a civil war against separatist rebels. These concerns, however, should not be allowed to hinder aid operations. The importance of the relief effort is even clearer now that disaster has struck again.
The earthquake hit an area where people are still struggling to rebuild their lives - and livelihoods - after the trauma of the tsunami. They deserve sympathy - and they need long-lasting support.