While the earthquake that struck near Isleton Wednesday morning wasn’t strong, the location did raise questions about the possible risk to an area that is critical to the state’s water supply.
The Delta region in Sacramento County relies on more than 1,000 miles of aging levees to protect local farms and communities that could be vulnerable in a more powerful quake.
The shrinking and drying out of the Salton Sea has reduced stress on the San Andreas Fault, possibly reducing the frequency and severity of earthquakes in Southern California, according to research from San Diego State University and Scripps Institution of Oceanography.
The study, published Wednesday in the journal Nature, found that the reduced stress on the fault from a significantly lesser amount of water may be delaying the next “big one.”
Local utilities are looking for new ways to make Southern California earthquake safe, and one way is by replacing aging water pipes.
The new pipes could help keep the water flowing after a big one hits. LADWP is replacing critical areas along its 7,000 miles of water pipes in Los Angeles with earthquake resilient pipes to ensure water is still flowing after the shaking stops.
In a dramatic decision that could significantly impact Silicon Valley’s water supply, federal dam regulators have ordered Anderson Reservoir, the largest reservoir in Santa Clara County, to be completely drained starting Oct. 1.
The 240-foot earthen dam, built in 1950 and located east of Highway 101 between Morgan Hill and San Jose, poses too great of a risk of collapse during a major earthquake, the Federal Energy Regulatory Commission, which regulates dams, has concluded.
“It is unacceptable to maintain the reservoir at an elevation higher than necessary when it can be reduced, thereby decreasing the risk to public safety and the large population downstream of Anderson Dam,” wrote David Capka, director of FERC’s Division of Dam Safety and Inspections, in a letter to the Santa Clara Valley Water District on Thursday.
Earthquakes could have a major impact on San Diego’s water supply, even if they happen far away. That’s because San Diego’s water comes from hundreds of miles away, through threads of metal and concrete that connect us to distant rivers and reservoirs. Our biggest source of water is the Colorado River, which is diverted into Southern California from the Arizona border through a 242-mile water system that includes 92 miles of tunnels. On this week’s San Diego Explained, Voice of San Diego’s Ry Rivard and NBC 7’s Catherine Garcia lay out three worst-case scenarios that could affect San Diego’s water when an earthquake hits.
The impact of an earthquake will not respect borders. Much less, a quake that will be registered in the fault of the Rose Canyon. For the past five years, researchers and authorities on both sides of the border have been preparing a seismic and damage scenario for the San Diego-Tijuana region, the findings of which will be presented to the population next March. The purpose is to know what would happen if there is an earthquake of magnitude 6.9 in this fault that passes through the center of the city of San Diego and is projected to Tijuana.
Seismologist Lucy Jones hikes through a dirt trail into a canyon, past a riverbed, and through some brush in Altadena. She kneels down and points at a thick layer of greenish-grey clay, snaking through the sloping terrain among rocks and dirt.
“This is the fault! Isn’t it amazing?”
San Diego faces a hidden earthquake threat — to its water supply. A quake, even one so far away that nobody in San Diego feels it, could cause an emergency and force mandatory water-use restrictions. That’s because most of San Diego’s water comes from hundreds of miles away through threads of metal and concrete that connect us to distant rivers and reservoirs.
The Water News Network is San Diego County’s source for water news and information.
