I was visiting a place while a mild earthquake. It didn't cause any damage, but it took many locals by surprise, as it didn't take place in a seismic country.

Naturally the mobile phone network, GPRS/3G that POS devices relied on was overwhelmed. And maybe something else went wrong on the banks backend.

So international credit card transactions were hit or miss for half a day. I was happy I had got some local before the earthquake. So I was able to continue the rest of the day with no issues.