This week has been a tragic one for parts of Southern California. Heavy rains have triggered landslides and mudflows that have killed over 17 people with dozens more missing. Now, this tragedy is a sequel to an earlier disaster: wildfires that ravaged the coastal mountains near Santa Barbara. However, they are two events that tend to go together because the effects of one prompt the other.

The wildfires that burned forests and homes in 2017 have the net impact of destabilizing rugged terr