Geoscience Reference
In-Depth Information
23. The San Andreas fault system in California is not a single crack in the Earth's
crust. Even this map is simplified.
When the ground turns to liquid
If you've ever stood on a wet sandy beach and jiggled your foot up and down, you may
have noticed that water tends to rise in the sand and your foot sinks in; the sand liquefies.
The same thing happens when an earthquake shakes wet sediments. The epicentre of the
Mexico City earthquake in 1985 was 400 kilometres away, yet many buildings in the city
