an earthquake

I was filling my glass by the water dispenser at the office, when my friend said "I think it's an earthquake..."
I stood still and true enough my body swaying slowly... all of us looked at each other, grabbed our bags and half running towards the lift... gee... we're on the 20th floor!!!
We finally reached the ground floor safe and stayed there until we thought it was safe to go back to the office. Strangely, no announcement made by the building nor my office management.
Later I learned that tsunami hit southern part of Java. What we felt was not the earthquake but when the wave hit the shore...