The cities of Manila, Malabon, Valenzuela, Pasay, Parañaque and several Cavite cities on the fringes of Manila Bay are land formed from the deltas of various rivers. These are all aluvial deposits where liquifaction can occur.

On the other hand the cities of Quezon City, Marikina, Pasig, San Juan, Mandaluyong and Makati are all on top of what is called the "Guadalupe Schist", named after that big rock formation you see on Guadalupe on the Pasig river. This rock was from volcanic deposits of ash that have been compacted and formed the "adobe" and "escombro" that you now find when you dig under these cities. Escombro is not adobe but the softer less compacted version of it, normally found on top of the adobe.