Past earthquakes may help predict future quake damage

Evidence from past earthquakes can be used to help predict the damage from future quakes in developing countries that may lack extensive seismic monitoring, scientists say.

Researchers have used innovative methods to examine the ground around Mbeya in Tanzania where a large earthquake occurred some 25,000 years ago.

They found evidence of fluidisation (where soil behaves like quicksand) and upward displacement of material which is uncommon in a continental setting, raising questions of how the rapidly growing cities of the region would fair in the event of a major earthquake.

"We can now use this to evaluate how the ground would deform in a modern earthquake," said Eric Roberts of James Cook University in Australia.

"This is important because the approach is inexpensive and can be used to model how structures might be affected by future events, providing a valuable tool in hazard assessment," he said.

According to lead researcher Hannah Hilbert-Wolf, the team found evidence of massive ground deformation and previously unknown styles of liquefaction and fluidisation, caused by past earthquakes.

"This could be a major concern for the growing urban population of East Africa, which has similar tectonic settings and surface conditions," she said.

The research comes on the back of a series of damaging earthquakes already this year, including in Nepal and Papua New Guinea and the study may be of much use in predicting the effects of future earthquakes in those countries, researchers said.

"What we have shown is that in developing countries in particular, which may lack extensive seismic monitoring, the rock record can be used to not only investigate the timing and frequency of past events, but also provide important insights into how the ground will behave in certain areas to seismic shock," said Hilbert-Wolf.

It is estimated that by 2050 around 130 million people will live in Tanzania, mostly in constructed urban settings that are more susceptible to earthquake damage and surface deformation than traditionally fabricated buildings.