A Look at the Delta through the years and the latest attempt to mess with Nature or Revise the Delta!

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Seismic Risk and Earthquakes in the Delta ... and California
What is the seismic risk in the Delta? 

Fact:  No levee has been know to fail from any of the earthquakes in California
.  The media, which is probably controlled by those who wish to export even MORE Sacramento River water, have been using the public's fear of earthquakes to fabricate a sense of risk of levee failure in the Delta despite the fact there's never been a Delta levee failure as a result of an earthquake since records have been kept for California.  Since horizontal hydraulic fracturing is emerging as a natural gas exploration that results in KNOWN incidents of "induced seismic events" in other areas of the country, perhaps the people and agencies know the fracking already permitted in the Delta may induce levee failures.  There were field studies going on in 2004 in the Delta by Jones Tract and Bacon Island.  Could fracking test sites caused the "sunny day" failure of that levee?  Despite the facts, Department of Water Resources or water contractors have paid for researchers from UCLA and other engineering/science organizations to test earthquake impact on Delta levees.  In 2011 some UCLA engineering scientists did a test on Sherman Island and they could not get their fake levee, made for the test, to fail.  On 8/15/2012 more tests were conducted on a fake levee constructed in the middle of Sherman Island, which made the ground move as the equipment monitored the movement effect on the layers of peat below the fake levee.  The scientists there said they believe the deep of Sherman Island (deepest area of the Delta) makes the motion from an earthquate intensify in waves, rather than diffuse over an area.  Dr. Pike, often quoted by Restore the Delta newsletters, confirmed his belief of just the opposite-that peat may act as a cushion or absorber of the engery force from and earthquake.

Of course, an earthquake can happen anywhere, and failure of certain levees might put water quality of water exports at risk for a short time, which is the very reason WHY water exporters are focusing on levee integrity on Sherman Island.  However, it is much more likely both Los Angeles area and SF Bay area would receive that feared "big one"...why not focus on limiting development and populations in the high risk areas of California instead?  History shows the Delta is a low risk area for Earthquakes so shouldn't a concerned legislature prohibit high density development in high seismic risk area instead of targeting the low risk, low density area of the Delta?

Please review the  many maps and document links below  if you want  to know the historical FACTS compared to what the media or DWR wants you to believe.  Then ask the following logical questions:

1.  If the risk of earthquakes is HIGHEST in the San Francisco Bay area, (look at the liquification maps) including areas like the Oakland waterfront, San Jose and Santa Clara, WHY are those areas being promoted for high density development-one of the reasons water agencies are after more Delta water in the Bay Area?  Ask the same question for LA area:  Why promote high density development in the highest seismic areas of California?

2.  Since Delta levees have never been known to fail as a result of an earthquake, wouldn't the scientists be wiser to spend their time studying WHY the levees haven't failed or liquified?  Perhaps the peat soils of the Delta act as "shock absorbers" or a huge sponge that absorbs the impact of the earthquake movement in the area, so the levees stay intact?  Perhaps engineers could find better methods for creating buildings that can withstand inevitible earthquakes in California by studying what is RIGHT about Delta soils that history shows seems to do just fine in times of earthquakes?

3.  Regarding risk to Delta islands and area, if the scientists writing the reports can't even figure out which island is where, why would anyone believe their "results?  (See wrong maps study or the 2005FloodedIslandFeasibilityStudyBaselineReport.pdf, noting the baseline map of the Delta provided.  (the report is a large file so it will upload to your computer slowly)

Anyway, below are maps from studies related to seismic risk in the Delta, and all of California.  Since Delta land elevations and subsidence can affect seismic risk, there is additional information on those topics at the Elevations-Subsidence section also.  Click on the maps to see full size versions of each, or click on the links to go to the studies referenced.   Pay close attention to the colors indicating risk levels, and to the dates the maps were produced, and by whom or which agency the maps were produced.  In particular, the first "final" version of the DRMS Report Phase 1 uses false data regarding Delta islands upon which to base the risk calculations.  If the underlying or raw data is fabricated doesn't that meant the entire section of results based on fabricated data is at least partially wrong?  What would a math teacher tell you if you started your equation by filling in the wrong initial numbers?

Given the very poor condition of the gas lines in the Bay Area, according to news media, shouldn't the focus be on replacing those gas lines and discouraging the need for new gas lines for development in high seismic risk Bay Area and SoCal communities?  Ask yourself...are you more at risk from being blown up or burned from a gas leak after an earthquake, or at risk from being flooded?
note the Delta map from this report!

To see many more maps that look at elevations & seismic rist, go to this page



There are TWO islands named "Ryer" in the Delta, both located within Solano County boundaries.  This might explain one reason the DRMS Phase 1 report provided false data on the history of the "Ryer Island" northeast of Rio Vista-an island that has much lower seismic risk, and has not flooded in the last 100 years.

Note that soils tests were also conducted in Suisun Marsh area, and the soils test of the Suisun-area "Ryer Island" was accidentally or negligently used for at least one DWR report on soils types in the Delta, transposing the soils type of the Suisun-Ryer with the soils type of the Steamboat Slough area Ryer Island!


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Compiled by Delta citizens and Delta Voices Last Modified :01/15/14 04:34 PM Copyright 2009-2013 ,