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Geologic Hazards

Mega Earthquake Could Strike Closer to Seattle

Preliminary results from a study related to the subduction of the Juan De Fuca Plate beneath the North American Plate off the coast of Washington and British Columbia indicate that the potential mega-thrust earthquake could […]

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Geologic Hazards

Landslides in China – Sichuan and Guangxi

In Sichuan Province, China, they were still in the recovery process from the devastating 2008 earthquake when a series of landslides, rockfall, mudslides and flooding has hit the region. Dave’s Landslide Blog has excellent coverage as usual on the slide pictured here, which blocked a major road, hindering rescue efforts. (Photo Xinhua/Jiang Hongjing)

A remarkable video of the aftermath of a bridge destroyed by one of these rockfall / landslide events is shown below. The destruction is pretty profound. (Via Geology.com)

Also on Dave’s blog, a landslide in Guangxi caused a train to derail, killing 4 people and injuring 50. My heart truly goes out to the people of those portions of China, particularly in Sichuan as they have been through so much.

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Geologic Hazards

Maitland Sinkhole Stabilization Project – Central Florida

image A massive sinkhole more than 300-ft in diameter and with depths to bedrock of up to 350-ft is located under a future I-4 traffic interchange in an Orlando suburb. A massive $9 million stabilization project is underway to prepare the site for the eventual TI construction. The size of the Maitland Sinkhole is on par with the largest sinkholes to form in central Florida in recent times. There is not a void present, instead it is infilled with a compressible sand deposit. (Image from FDOT)

The mitigation method includes drilling over 300 grout injection holes, and performing grouting operations to infill cracks in the limestone bedrock. Then in the same holes, compaction grouting will be used as a method of ground improvement to densify the sand in place. Once the grouting is complete, the site will be surcharged to compress any remaining weak layers. Click through for a subsurface profile and location map. Via ASCE SmartBrief.

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Devil's slide repair of PCH 1 using
Geologic Hazards

Devil’s Slide Repair and Tunnel Bypass Presentation

Devil's slide repair of PCH 1 using [Updated Thursday May 29, 2009 – 1:00 PM PDT] Added a photo of the AIS Kaiser S2 excavator (spider excavator), and added photos of the Devil’s Slide debris dump where they have put the landslide material removed and the material from the tunnel excavation. [/Update]

Grant Wilcox, Geology Branch Chief with CALTRANS Office of Geotechnical Design West gave a presentation on the Devil’s Slide repair along PCH Highway 1 at the Southwest Geotechnical Engineer’s Conference on May 12 in Phoenix. I’ve posted about the project here before. When I saw Mr. Wilcox, I knew he looked familiar but I couldn’t figure out why. At the beginning of his presentation he made light of his being on You-Tube…then it clicked! He gave a nice overview of the history of the failures, the geology, and the tunnel project. What follows are a few quick tidbits from his talk based on my notes. (Photo via Caltrans site).

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