Hayward Fault Earthquakes

By Howard Cook, Founder and General Manager of Bay Area Retrofit

 

 The Dangers of the Hayward, San Andreas, and Cascadia Fault Lines

Since the year 1315, the longest period of time between five major Hayward Fault earthquakes was 160 years.  The average was 138 years.   October 21, 2008 was the 140th anniversary of the 1868 Hayward Fault earthquake, a magnitude 7.   In 2016, we are now at 148 Years!  That’s 10 years beyond the average rupture cycle and 12 years before the maximum rupture cycle.  In other words we are in trouble.

Below is a graph from the  UC Berkeley Seismological Laboratory.  The laboratory also publishes a FAQ page that will tell you everything you want to know about our seismic geology.

USGS

The USGS has a webpage where you can see exactly where you are in relation to major faults such as the Hayward Fault.  As of April 1, 2017 this page was being updated and is not accessible.  In lieu of this some very interesting information about our local geography can be found here.   

According to government statistics, a quake on the entire Hayward fault would reach magnitude 7.3.  It would leave over 155,000 housing units uninhabitable.  Over 350,000 people will be displaced.   Damage to residential buildings will be $90.4 billion; commercial buildings, another $96 billion.   See The Coming Bay Area Earthquake, page 75, by the Earthquake Engineering Research Institute.

An Hayward Fault earthquake is expected very soon. and may rupture other faults.

The Bay Area is riddled with numerous earthquake faults.

On page 10 of Seismic Behavior of Level and Stepped Cripple Walls by Y. H. Chai, it states, “More than half of the $40 billion dollar property losses in the Northridge Earthquake were due to failures of wood frame construction, primarily as a result of the damage or collapse of residential, single-family homes ……………..”  Damage from the Hayward Fault will greatly exceed this.

San Andreas Fault

The Devastating Potential of the Cascadia and San Earthquake Fault Lines

New studies described in a New Yorker article, “The Really Big One,” warn that the Cascadia Fault is even more dangerous than the Hayward Fault.  Kathryn Schultz, the author, was awarded the 2016 Pulitzer Prize for Feature Writing.  “When the next very big earthquake hits, the northwest edge of the continent, from California to Canada and the continental shelf to the Cascades, will drop by as much as six feet and rebound thirty to a hundred feet to the west . . . To see the full scale of the devastation when that tsunami recedes, you would need to be in the international space station.”  FEMA conservatively anticipates a death toll near 13,000.

Here is an eye-opening,  7-minute TV clip on the Cascadia Subduction Zone.    This fault regularly generates 9.0 temblors similar to the 2004 Sumatra earthquake and tsunami that killed over 227,000 people in Indonesia and India.  The 2011 Tohoku 9.0 earthquake that caused the Fukushima nuclear disaster is discussed in this 3-minute video.

This 50 minute long BBC documentary on this earthquake fault also points out that it triggers the San Andreas Fault to rupture 75% of the time, which in turn can cause the Hayward Fault to rupture.

 

A very real possibility if the Cascadia Subduction Zone Reuptes

This devastation is practically inevitable when the Cascadia Fault ruptes

 Below is the repeat cycle for the Cascadia Earthquake Fault.

Anticipated occurrence of earthquakes on the Cascadian Subduction Zone.

The subduction zone is larger than the Hayward Fault

The Cascadia Fault is on the left, the equally sized Sumatra Fault which caused 260 thousand deaths on right.

 

A Hayward Fault Earthquake in Comparison to other Earthquakes

It is expected that when the Hayward Fault ruptures there will be $165 billion in damage.  The chart below should give you some perspective on how much devastation this is.

The Hayward Fault Earthquake will cause more damage than all previous earthquakes combined.

A comparison of the damage cause by California earthquakes since 1933

 When the shaking starts

While the author of this article was employed by the Federal Emergency Management Agency he evaluated injuries and discovered that 99% of the injuries were caused when people tried to run out of the house.  While trying to stand up or run, people are thrown against a wall, appliances or down the stairs.  When the shaking starts, drop and crawl away from any object that may fall on you, cover your head, and stay there. If you have children, crawl to their aid, do not run.  Retrofitting will reduce the intensity of the shaking, but you will still be terrified but know there is no record for deaths in houses, except in hillside homes.

 

Member

eeri-logo struc-eng-icon icc-icon

Headquartered at:

Bay Area Retrofit
427 San Pablo Ave
Albany, CA 94706
With field offices in San Jose and Hayward.

Company License Info

Works' Comp #3900008328-011
Contractors Lic #558462
Bond #511-67-26
Liability Ins GL 3984008