Category Archives: Geology

Fault, Geology, Hemet, Image, Riverside County, San Jacinto Fault

Image of the Week – 11/11/14

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Bautista Canyon between Hemet and Anza in Riverside County. This follows the San Jacinto Fault.
Bautista Canyon between Hemet and Anza in Riverside County. This follows the San Jacinto Fault.
Geology, Hiking, Image, Los Angeles County, San Gabriel Mountains

Image of the Week – 11/1/14

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On the trail to Mt San Antonio along Devils Backbone.
On the trail to Mt San Antonio along Devils Backbone.
Baja California, Earthquake, Geology, Image, Mexico, Old Alignment

Image of the Week – 9/15/14

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Old alignment of Hwy 2, now offset by about 2 feet horizontally and 5 feet vertically.
Old alignment of Mexico Hwy 2, now offset by about 2 feet horizontally and 5 feet vertically.
Earthquake, Geology, San Bernardino County

M4.6 near Big Bear Lake, CA

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At 9:59am on July 5, 2014, a M4.6 earthquake struck near Big Bear Lake. The focus was 5.4 miles deep.  If you felt this earthquake, the USGS wants to know! Watch for debris on the roadways in that area (State Highways 18, 38, 138, 173, 189, and 330).

Shakemap showing intensity.
Shakemap showing intensity.
Map showing area where people felt the quake and at what intensity.
Map showing area where people felt the quake and at what intensity.
Baja California, Earthquake, Geology, Mexico, Old Alignment

April 2010 Baja Quake – Part 2

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In July 2010, I was able to go to Baja California with a friend. Part of our route traversed Federal Highway 2 (Mexico), which suffered some damage from the April 2010 quake. Hwy 2 had been repaired but the adjacent old alignment had not been. I was rather amazed at the amount of offset from this earthquake. I observed about 2′ of horizontal and about 5′ of vertical offset at the highway crossing.

East of the fault, bridge embankments on the Hwy 2 Mexicali Bypass show signs of settling.
East of the fault, bridge embankments on the Hwy 2 Mexicali Bypass show signs of settling.
Offset right of way fence next to Hwy 2.
Offset right of way fence next to Hwy 2.
Old alignment of Hwy 2, now offset by about 2 feet horizontally and 5 feet vertically.
Old alignment of Hwy 2, now offset by about 2 feet horizontally and 5 feet vertically.
Side view of the old alignment showing the vertical offset.
Side view of the old alignment showing the vertical offset.
Breaks in the soil to the north. Two distinct scarps can be noted here.
Breaks in the soil to the north. Two distinct scarps can be noted here.
At the break, the old alignment now has a steep ramp and crack.
At the break, the old alignment now has a steep ramp and crack.