The Hidden Fault That Could Destroy Los Angeles

Beneath the towers of Downtown Los Angeles runs a fault that appeared on no geological map for a century. It has moved four times in the past eleven thousand years. And with every millennium that passes, it moves a little faster.

The Puente Hills blind-thrust fault was identified in 1999 by Harvard geologist John Shaw and Scripps seismologist Peter Shearer, working from oil-industry seismic reflection files that had sat unread for decades. Its full rupture scenario is modeled by the United States Geological Survey as one of the costliest natural disasters possible in the continental United States. And in 2017, a paper in the journal Geology showed that the fault's slip rate has accelerated six-fold since the last Ice Age.