Category Archives: Geology

District 6, District 8, District 9, Earthquake, Geology, Highways, Inyo County, Kern County, San Bernardino County, Searles Lake, SR-178, USGS

Earthquake UPDATES – Mw 7.1 near Ridgecrest

Well, that was strong! I felt it here in San Diego. First time I felt my building sway and it shook for a while. USGS is now reporting the quake as a Mw 7.1, which is 11 times larger than the one yesterday. This, assuming a larger one doesn’t happen, has also been deemed the “main shock” and the 6.4 was the “fore shock”. USGS and Caltech are a bit slow right now. If you felt this one, please let USGS know once their servers are not slow or not working. They need your help!

From Caltrans and CHP, damage reports are coming in of rockfalls on 178 in Poison Canyon, a sinkhole on 178 near the Trona Pinnacles turnoff, and buckling up to 4 feet as well as large cracks in other areas. Do not drive fast through any of the earthquake affected areas. Also be aware that rockfalls will be likely in all the local mountain ranges, so be careful. State 127 near Ibex Pass is covered with rocks, and that is a fair distance away from the epicenter.

http://scedc.caltech.edu/recent/
Working map of all earthquakes in California and Nevada by Caltech. Links to USGS as well on the page.

USGS site now working!
https://earthquake.usgs.gov/earthquakes/eventpage/ci38457511/executive

Earthquake, Geology, Kern County, Ridgecrest, San Bernardino County, Searles Lake, Southern California

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!

Fossils, Geologic Study, Geology, San Diego, San Diego County, South Park

San Diego Fossils

I’ve been doing a bit of work lately on my geologic study of central San Diego and have found many fossil sites. So far, none of the fossils have been very complete. Mostly shell fragments in condensed layers. The oldest found so far have been from the Eocene Mission Valley Formation, which is between 40 and 48 mya.

Small shells within the Mission Valley Fm in Presidio Park.

In addition to the fossils found in Presidio Park, I have also found a few locations around Hillcrest and South Park. Some of these are just the side of the road, others you have to hike a bit in a canyon.

Fossil shells (mostly bivalves) within the San Diego Fm.

Underlying the southern half of the central San Diego Mesa is the San Diego Formation, which is late Pliocene to early Pleistocene in age, about 5 to 1.5 mya. It has many layers containing fossils, such as the one pictured above.

Once you get the “eye” for fossils, they seem like they pop up everywhere. It would seem that every time I go out on my mapping project lately, I find fossils. Geology can be a lot of fun and I encourage all interested to go out and explore their local area. You never know what you might find.

Geologic Study, Geology, Highways, Ridge Route

Geologic Report

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In January, I was asked to do some research regarding the potential for a landslide on the Ridge Route near Templin Highway. I thought it would be a good opportunity to get some practice writing a geologic report. While I’m not a professional geologist, I still find it a lot of fun to do . I added a copy of the report on this site, available for download. I would love to hear feedback from any other geologists out there.

Ridge Route Geology Study – Preliminary

Geology, Los Angeles County, San Gabriel Mountains

Mt Wilson Observatory Geology Talk

Lectures

On Saturday, June 16, at 5:30 pm Mount Wilson Observatory will be hosting a talk by Dr. Tanya Atwater, professor emeritus of geology at UC Santa Barbara. Dr. Atwater played a major role in piecing together the plate tectonic history of our part of the planet. She will talk about how the motions of the Earth’s crust created the current topography of southern California (including the perfect site for astronomers to explore the Universe). The talk will be followed by a rare chance to look look through Mount Wilson Observatory’s 60-inch Telescope, which revolutionized telescope design and allowed astronomer Harlow Shapley to find our place in the Milky Way Galaxy. Tickets are only $20 and proceeds will all go to the maintain the Observatory.