Some months ago my inbox was blessed (not) with an email of a photostat copy of a newspaper clipping in which it was said that Durban would soon experience a horrific earthquake. Now, I’m the type of person who immediately sees these types of emails as hoaxes until I get some kind of concrete proof that they are true.
But then yesterday there were reports of a tremor felt in parts of Durban. So I took out my detectives hat and did some sleuthing. According to timeslive.co.za hundreds pf people in Durban North, Umhlanga, Phoenix and Verulam reported feeling the earth shake, but there was no reading on the local magnitude scale. So, it was a really tiny earthquake. But it got me thinking. Is there really a chance that Durban could be hit by a mega earthquake and be totally destroyed?
The guys over at East Coast Radio spoke to Craig Smith (Executive manager of the Geological Society of South Africa).
"From the description I’m hearing, it sounds like a very low magnitude earthquake. If you don’t feel it while you’re driving; you feel a little bit of shaking, it’s probably under-magnitude two. These kind of earthquakes can happen all over the world at any time."
He says, generally speaking, the Durban area should be free of earthquake activity. There is, however, a zone of weakness in the African plate which ends in the Lesotho region.
"It’s slowly but surely splitting apart. So, you can expect some seismic activity at times along that zone and we do see it. Having said that, it is a very rare event where we see an earthquake like that – and it’s certainly very rare to find something like that in Durban."
If you follow this link you can download a pdf document which talks about seismic activity in South Africa. ( www.aon.com/attachments/reinsurance/201006_mega_eq_report.pdf) Here is an excerpt form the article:
Seismic risk in Durban
Durban, the largest port city in South Africa, is located next to the warm Indian Ocean and is not regarded as being exposed to high seismic risk. A magnitude 6.3 event occurred at St Lucia Estuary, about 220 km north of Durban, on New Year’s Eve 1932 but – unlike Cape Town – there is not an active known fault close to the city.
The return periods for earthquakes of magnitude 5.0 and 6.0 were assessed considering all seismicity within a 300 km radius of Durban. From this research, it is estimated that an earthquake of magnitude 5.0 could cause structural damage only if its epicentre is less than 45km from Durban. The return period for such an event is about 735 years.
Using the Moses Mabhida Stadium as a case study, for a magnitude 6.0 event and larger to occur and have a damaging impact, the epicentre must be closer than 90km. The return period for such an event is about 5,000 years. It is clear that earthquakes are not a significant risk to insured structures in Durban, although the contribution to expected losses must be taken into account.
Here is an interesting article about earthquake activity in Africa – http://www.scienceinafrica.co.za/2010/february/earthquake_SA.htm
So, in my opinion, Durban is safe from doom. For the next few hundred years anyway.