Quicksand is mainly water and sand so it makes sense that it eventually leads to a water source underground.
(1) Meteorological/Climate factor:
-Rainfall intensity
-Rainfall amount
-Rainfall duration
-Distribution of rainfall over the drainage basin.
(2) Phsyiographic factors (e.g. watershed)
- watershed size
-Watershed shape
-watershed slope
(3) Vegetation
- Dense vegetation leads to less run-off while sparse vegetation leads to more run-off.
(4) Urban development.
- Roads and buildings have do not allow infiltration into the soil. Water will therefore run off directly into the stream, at a very fast rate and in significant volume.
The answer for this is Tokyo