The ceiling of my house suddenly collapsed. What is the sign? earthquake?

There must be many reasons for this drop. A simple drop does not mean it is an earthquake, because an earthquake is a destructive pressure, but from the situation you told, it is not too serious. If it is broken, compare it with the surrounding neighbors to see 1. The reason for falling may be: the load-bearing wall is cracked and there is a problem with the main structure. 2. The reason for falling may be: there is a quality problem with the ceiling hardening and the design strength is not enough. 3. The reason for falling Possible reason: The load-bearing pressure upstairs is too great.