Durban - A University of KwaZulu-Natal geophysicist says the province has for the past year experienced earthquakes that have been felt over large areas.
Dr Mayshree Singh, a geophysicist and lecturer at the school of engineering at the University of KwaZulu-Natal, was commenting after the province experienced earthquakes on Saturday and Sunday.
According to the Council for Geoscience the two quakes both had a preliminary magnitude of 3.9 on the local magnitude scale as recorded by the South African Seismograph Network (SANSN).
Singh said earthquakes in the KZN region are naturally occurring along known geological structures.
She said earthquakes bring about fear because of the sudden and extreme levels of destruction witnessed internationally.
“Earthquakes, such as those that occurred in Haiti, Afghanistan, Nepal, China and Japan, have been followed by landslides and, in some cases, tsunamis which caused large scale damage and loss of life.”
However she said it was important to remember that Southern Africa is situated on a relatively stable part of the African continental plate.
“While we do have accumulation of stress on faults, we do not expect large magnitude earthquakes such as those located near the margins of continental plate boundaries.
“Also, our large building infrastructure mostly conforms to strict building codes and practices, which often allows for some levels of ground movement. Awareness is the key.”
Singh said that an earthquake or an earth tremor refers to the same phenomena.
“A high energy shock-wave is released within the earth surface and travels several hundreds of kilometres outwards from the energy source called the epicentre. Often people associate earth tremors with minor levels of shaking, with people only having felt the vibrations with no associated damage. In contrast, an earthquake is often related to strong shaking, which causes structural damage.”
Singh added that earthquakes are caused mostly along geological faults but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests.
“Earthquakes occur in SA every day. They are detected by sensitive instruments called seismometers positioned throughout the country. The smaller naturally occurring earthquakes of Moment magnitude below about 2 often go unnoticed by the regional seismological network.The types of earthquakes in SA are usually due to mine blasts and stress release on geological faults.”
Singh said that extensive research in the field of earthquake risk and vulnerability is ongoing by researchers in the country.
“This research is often funded by national universities and government-funded research institutions. Densification of the seismological network in the KZN region will help in improved location and depth of the earthquake epicentre and understanding the type of movements along the geological faults.”