Most people think that time and war are responsible.
But we now know that actually most of the damage was caused by historical earthquakes. Simple examples are Troy, Micenea, Crete, or ancient Jericho. Because it is situated on top of an active earthquake fault we believe now that many of its 32 layers of destruction are the result of repeated past earthquakes. Another example is the huge earthquake of 31 BC in ancient Judea. We now think that this earthquake caused collapse in many caves in the Qumran area where the Essenes wrote the Dead Sea Scrolls.