Significant lessons learned from the 1987 Whittier Narrows earthquake – Orange County Register

The Whittier Narrows quake struck 30 years ago this Sunday, Oct. 1. It wasn’t the most deadly or most costly temblor in California, but it set many things in motion to help us deal with future earthquakes.


The magnitude 5.9 earthquake caused eight deaths and an estimated $358 million in damage (adjusted to 2008 dollars). Homes were damaged in Los Angeles, Orange and Ventura counties in the strongest quake in Southern California since 1971.

Statewide impact

The quake occurred on a previously unrecognized fault and was the first sign that the Los Angeles basin was on what is now called a blind thrust fault. The second major quake from such a fault was the Northridge shaker in 1994, which killed 57 and inflicted $44 billion in damage.

The search for blind thrust faults has been on since the early 1990s.

What lurks beneath

The Whittier quake took place in the Puente Hills thrust system, considered one of the highest-risk faults in the U.S. because it is underneath a heavily populated area.

Matter of magnitude

Measuring earthquakes accurately has come a long way since 1987.  The USGS website shows earthquakes occurring around the world in real time and what their magnitude is.

Shown above are examples of magnitudes and how vast the difference of fault slippage is. California has not had a magnitude 8 quake since records have been kept.

The energy released in a magnitude 7 earthquake is about 30 times more than the energy released in a magnitude 6 earthquake.

Getting the alert out

There were just a few seismic monitoring stations in California before the Whittier quake, and now there are 740. California is trying to fund an earthquake early-warning system that can send a message to your computer or mobile device seconds to minutes in advance.

How the system works:

When an earthquake occurs, it sends out three types of waves: P-waves, S-waves and surface waves. The P-wave is the initial wave detected by seismometers. It…

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