Johannesburg Earthquake - 21 June 2014

At about 17.30 I saw a number of retweets from @Abramjee about earth tremors being felt in the Johannesburg/Pretoria area:

Joburgers are you feeling this earth tremors?! #scared #johannesburg

— natasha stander (@iamtashastander) June 21, 2014

Just felt 3 tremors in my area of #mayfair west, #Johannesburg now. Did you? May ALLAH TA’ALA PROTECT US FROM ALL CALAMITIES. @radioislam — Qari Ziyaad Patel (@QariZiyaadPatel) June 21, 2014

Two light earth tremors in Randhart Alberton. About 5 min apart. Nothing serious but one could hear and feel it.

— Wolfram Zwecker (@wolfzwe) June 21, 2014

Having fact-checked a previous earth-shaking event I knew exactly where to go for the information. I hadn’t spotted it before but although the network states that reports are received every 10 minutes the charts were showing about an hour’s lag from real-time (even allowing for time zones), so the truth wasn’t available for another hour or so.

Now the truth has been revealed, and yes, it looks like there were a couple of tremors detected at both Lobatse and Boshof.

Seismogram of 21 June 2014 Johannesburg Earthquake – Lobatse Station

Seismogram of 21 June 2014 Johannesburg Earthquake – Boshof Station

The tweets above occur around 17:10, and the charts are in UTC/GMT so the traces around 15:05UTC to 15:10UTC correspond, given the magnitude and a slight offset in the timing it looks like the event was closer to Lobatse – in the same way as the previous event linked above. Interesting that there don’t seem to be any reports of an apparently larger event at about 14:17UTC – maybe the single events fade into the background?

Hopefully we’ll see some more informed commentary in tomorrow’s newspapers.