Los Angeles has been tormented by earthquakes throughout its history.
The whole area is subject to constant seismic activity, with low magnitude earthquakes occurring on a daily basis.
Earthquakes occur along fault lines: breaks in the Earth’s surface where the two sections, called tectonic plates, stick and slide as they move past each other.
Just as when you rub your hands together, friction builds up between the surfaces of the two plates over time.
The energy produced by this friction can be released suddenly when the build-up is too great, which causes the plates to slip past each other, resulting in an earthquake.
The San Andreas Fault divides the rugged San Gabriel Mountains from the low-relief Mojave Desert with a straight and marked boundary.
This is one of the most famous faults in the world, and has
produced a number of huge and devastating earthquakes.
The 1994 Northridge earthquake killed 72 people and caused $20 billion worth of damage – one of the costliest earthquakes in American history.
The damage caused by this earthquake was aggravated by the physical characteristics of the area.
The Los Angeles area is built on a soft surface layer which sits on top of a base of harder bedrock.
This acted like “a bowl of jelly” during the earthquake, magnifying the shaking effects with devastating consequences on the natural and built environment.
Bounded by the physical obstacles of the San Gabriel Mountains and the Pacific Ocean, the entire city is built on this relatively soft surface, putting it at significant risk of impact from earthquake damage.
Movement on underwater sections of the fault can also cause tsunamis, huge waves with devastating effects.