Category Archives: Southern California

M 3.6 – 4km NNE of Granada Hills, CA

Shakemap from USGS showing the extent of shaking and major fault lines

On January 21, 2020, just a few days after the 26th anniversary of the Mw 6.7 Northridge Earthquake, we had another small jolt strike the San Fernando Valley. This one, while small, was felt over a wide area. If you are among the many that did feel it, the USGS wants to hear from you! These “Did You Feel It?” reports help them to understand earthquakes further.

Ridgecrest – Part 1

Finally posting the photos from my August 22, 2019 Ridgecrest trip. Part 1, which covers the fault rupture, is finally up. Part 2, which will cover the problems in Poison Canyon and Trona, are coming soon!

M 6.4 near Searles Lake, CA

Seismic activity map of the Ridgecrest / Searles Lake area as of 12:40 pm July 4, 2019.

At 10:33 am this morning, July 4, 2019, there was a Mw 6.4 earthquake centered a few miles northeast of Ridgecrest, California. The focus of the earthquake was mid-range in depth, about 10.7 km deep. So far, there have been numerous aftershocks ranging up to M 4.7 in size at the time of this writing. The earthquake is the largest to strike southern California in some time. The area to the northwest of the epicenter has been subject to earthquake swarms in the past as well, though usually only up to the M 5.0 range in size.

Shakemap from this morning’s earthquake

https://earthquake.usgs.gov/earthquakes/eventpage/ci38443183/executive
USGS summary of the earthquake

Due to the size of the earthquake, I would expect there to be a fair amount of damage to buildings in the Searles Lake, Trona, Pioneer Point, Ridgecrest, and Inyokern areas. If you live in any of these areas, let the USGS know about what happened. Your information is greatly appreciated and will help them better understand the effects of earthquakes.

https://earthquake.usgs.gov/earthquakes/eventpage/ci38443183/dyfi/intensity
Did you feel it? Report it to the USGS here!

Featured Image – March 12 and 13, 2018

Photo of the St. Francis Dam just before it collapsed.

Side view of the dam. Note the lack of any real spillways in the dam. Water was about one foot below the rim of the dam the day of the collapse.

This featured image covers two dates for a reason. The St. Francis Dam, a former dam in San Francisquito Canyon above Santa Clarita, California, collapsed at 11:57:30 pm on March 12, 1928. The ensuing flood caused a great deal of damage along the canyon and the Santa Clara River Valley. Over 500 lives were lost that night in, even in 2018, the second largest disaster by loss of life in California. The even had repercussions throughout the world. Following that event, dams, as well as other large projects, no longer were approved by engineers. Geologists had the final say, not engineers. Both geologists and engineers also had to be certified by their state government to work as professionals.

The head engineer on the project, William Mulholland, was a great engineer. He oversaw and helped design the Los Angeles Aqueduct, which was the largest and longest project of its time. It is still an engineering marvel today, more than 100 years later. The disaster ruined his career and during the investigation, he not only took full responsibility for the event, but also was said to have “envied the dead”. The collapse took a big toll on the “Chief” and he died a few years later.

This post is in memory of both those that died that fateful night in 1928 and to William Mulholland. A man that went from the “Savior of the City” to a pariah in just a few years.

Featured Image – 2/27/2018

Irrigation canal offset by the Imperial Fault on Chick Road just west of Barbara Worth Road in the Imperial Valley.