Category Archives: Geology

California, Disaster, Earthquake, Event, Fault, Geology, Southern California, USGS

Earthquake Information

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Felt an earthquake? Want to know where it was and how big? Follow the links below to get up-to-date information from the USGS and the California Geological Survey.

If you felt the earthquake, let the USGS know by contacting them at: “Did You Feel It?“ This data helps them determine magnitude of the earthquake, how the geology affects that, and how the type of structure reacts to the event. Most earthquakes larger than 4.0 are listed in the “Events”  section of the page.

Additional Earthquake Information:

Geology, Highways, Image, Los Angeles County, Old Alignment, Ridge Route, Ridge Route Preservation Organization, Roads, US 99

Featured Image – 4/7/2021

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Today’s featured image is a video. This was taken just a few days ago on the Old Ridge Route near Swede’s Cut. A rockfall in January 2021 has partially blocked the roadway with more material coming down in the near future. The rock, located in the Ridge Route member of the Ridge Basin Group, isn’t all that stable. Landslides still plague I-5 despite more modern construction methods.

For additional information check out the
Ridge Route Preservation Organization

District 7, Earthquake, Geology, History, I-5, Image, Los Angeles County, Santa Clarita, SR-14, US 6, US 99

Featured Image – 2/8/2021

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1970 view of the I-5 / SR-14 Interchange construction. This “build” would partially collapse on February 9, 1971 while still incomplete. Courtesy – Caltrans

To commemorate the 50th anniversary of the February 9, 1971 M6.6 Sylmar / San Fernando Earthquake, our featured image shows the construction work in progress on the I-5 and State 14 interchange in 1970. This work would be halted abruptly in the early hours of February 9, 1971. After this, it would be reconstructed two more times. The earthquake changed the way freeways such as this were built and did further seismic codes throughout the state.

For further information about the interchange:

Golden State Freeway / Antelope Valley Freeway Interchange
US 6 / US 99 Junction – Tunnel Station
Historical Photos of the US 99 / US 6 Interchange
CBR650FA, County Highway, Fault, Geology, Image, Los Angeles County, Motorcycle, Road Signs, Roads, San Andreas Fault, Southern California

Featured Image – 11/23/2020

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Along the San Andreas Fault

Near Valyermo, California, outside of Palmdale, the locals have placed signs where Pallet Creek Road crosses the San Andreas Fault. They picked a really nice spot too, as you have a sag area, fault scarp, and offset streams all easily visible from there. I recommend a visit!

Fault, Geology, Image, Los Angeles County, San Gabriel Mountains

Featured Image – 4/17/2020

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Step faulting, slickensides, and heavily fractured rock

The San Gabriel Mountains have been subject to quite a bit of deformation in their past. Some of which is still ongoing, such as the movements along the Sierra Madre and San Andreas Faults. Here, near Mt Wilson, the rocks exhibit multiple instances of deformation. The white vein is mostly composed of quartz, which has been offset by multiple faults. Slickensides can be seen as the reddish areas on the right side of the photo. The surrounding materials are complex metamorphic rocks.