TANC: Earthquakes and Landslides

 

Some History

The major earthquakes of the past few decades remind Californians’ that we live in a region where the ground is certain to sake and rattle sooner or latter. One of TANC’s alternative corridors takes its 500kV overhead transmission electric line adjacent to the foot of the  Blue-Ridge Berryessa Mountains which is a 750,000-acre corridor of still-undeveloped land which spans the range across Napa, Yolo, Lake and Colusa Counties. One of the greatest fears beyond an earthquake is the possibility of subsequent landslides.

In fact, in 1906 at the foot of the from Blue-Ridge Berryessa Mountains is Cache Creek where occurred one of the greatest land slides in California history, but its significance was lost due to the 8.25 magnitude earthquake that struck San Francisco only thirteen days earlier. The slide happened on May 1, 1906, near Crack Canyon, a tributary of Cache Creek. Residents downstream in Capay Valley noticed the creek level had dropped five feet overnight, but the slide area was so inaccessible that it was two days before the cause could be confirmed. The slide that completely blocked Cache Creek was one hundred feet high and 500 feet wide on top, impounding 12,000 acre feet of water in a lake four miles long. This could easily happen again. Installing a series of 150 plus high voltage towers near a known earthquake fault line with a history of landslides is very dangerous and must not be allowed.

 

Maps of Proposed Route Central 3

landslideTANC_risks_files/ca_landslides_small_2.jpg
seismicTANC_risks_files/transmissionline_1.png

Related Google Group

There has been lots of discussion on a Google Group that has been set up to exchange ideas and concerns about the TTP.  To access this, you have to join the Google Group. It is easy to do.

The 1892 Earthquake

In April 1892, a series of earthquakes rattled the western Sacramento Valley. Their epicenters were near Winters and Vacaville, both very small towns at the time.

The first quake, felt most in Vacaville, occurred on Tuesday, April 19th in the early morning. Damage was more apparent in brick buildings than wooden ones, shocking to many who thought brick was far more modern and superior to wood. In Winters, the same was true. Residents of both towns began rebuilding that day. In Davis a few chimneys were toppled, and one older building fell to the ground. However, in Dixon, a larger town, a fire as started after a lantern was knocked over, making rebuilding a bit harder to accomplish. The Tuesday quake had a magnitude of M6.5.

The second quake struck Winters on Thursday, April 21st at 9:40 am. It was stronger than the Tuesday quake, although only an M6.2, eliminating all remaining brick and stone buildings in Winters. The Thursday quake also resulted in the only fatality, Jeff Darby, who was behind the brick Cradwick Building as the earthquake occurred. He was pounded by falling bricks, and died in the hospital early the next morning. At 9:45 am, Vacaville felt the second earthquake. It brought down much of the standing walls and contributed to the panicked mood of the citizens.

Earthquake damage, looking east on Main Street, Winters, CA.

April 19th-21st, 1892

 

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