Why are aftershocks recorded?

Aftershocks produce some of the highest quality earthquake data for scientists to study.

Aftershocks can be used as "echo sounders" to study the local structure of the earth. Seismologists and geologists can find the orientation of the fault plane, which helps enormously in characterising the earthquake, and the stresses and strains within the Earth that caused it.

For these reasons seismologists and geologists are often the first people to arrive at the site of an earthquake. They deploy portable seismographs in order to record this valuable information. In the weeks after a big earthquake, scientists might record hundreds of aftershocks.

Deploying a portable seismometer above Sumner, Christchurch

Deploying a portable seismometer above Sumner, Christchurch. Caroline Ashenden © GNS Science