A few minutes ago I felt an earthquake, the first since I moved back to Indonesia. In Banda Aceh, I felt tremors all the time. Usually, it was nothing more than a mild vibration, something your stomach could manage. But once in a while you'd get a scary one, where the ground felt about as stable as a raft in a river.
This time I was in the office, on the 9th floor of a skyscraper. The room swayed, not much, but enough to tell you it wasn't just gas. I was on the phone with my wife at the time. I interrupted her to say there was an earthquake in progress. I tried, but couldn't keep the excitement out of my voice. She didn't share my enthusiasm.
You can tell if there was an earthquake by looking at the water inside the large bottles they use for water coolers. Every office has one, so it's easy to check. If it's sloshing around, you can be sure you just had one.