The catalogue of observations is incomplete, especially so with the old data. The development and employment of suitable mathematical methods is of paramount importance to seismicity studies because of the special features of the data. Applying the available knowledge on geophysical and geological issues belongs to risk analysis, too. The perception of seismic risk globally has also been affected by relatively new observations such as the impact of a major earthquake on the seismicity of the surrounding area. As a result of a major earthquake, the houses simply collapse on people.
Building technology is the best way to reduce the destruction caused by earthquakes.
Many earthquakes cause indirect damage since they can be followed by mud or landslides, sludge deposit or fires. Earthquakes may damage factories, nuclear power plants, gas pipes, dams or bridges and, therefore, the location of special buildings and infrastructure in general should be carefully planned taking into account the seismic activity of the region. The most destructive earthquakes claim the lives of tens of thousands of people, injure many more and leave hundreds of thousands of people homeless. The magnitude of the earthquake was 7.8 on the Richter scale and lasted less than a minute. The major earthquake was followed by some hundred smaller aftershocks.