earthquake – Page 7 – GeoPrac.net

The Claremont Tunnel – Designed to Survive Fault Rupture on the Hayward Fault

June 24, 2008 rockman Comments Off

The Claremont tunnel beneath the Berkeley Hills on the east side of Oakland is a water supply tunnel that serves over 800,000 customers in Richmond, Oakland, San Leandro and neighboring communities. One of the unique things about the tunnel is that it crosses the active Hayward Fault. Most of the time when you talk about designing for earthquakes youâ€™re talking about designing to withstand the seismic forces. In this case, the designers needed the water transmission tunnel to withstand up to 7.5-ft of offset due to fault slip and still maintain a minimum level of service. (Photo credit: Sue Bednarz, Jacobs Associates, Inc. by way of Civil Engineering Magazine)

This post describes the relatively recent Claremont Tunnel Seismic Upgrade Project as reported in Civil Engineering Magazine (May 2008, v. 78, no. 5, pp 58-63, 96-97).

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Sichuan Earthquake Update

May 21, 2008 rockman Comments Off

[Updated May 30, 2008] I forgot to publish this post to the front page, whoops! The two links still have excellent information. In particular, Dave’s Landslide Blog has coverage of the many landslide lakes and the efforts to breach some of them. [/Update]

The latest numbers according to AFP, Worldwide News Agency, is 71,000 dead, missing or buried and over 5 million homeless. There were many victims that were buried by landslides and rockfall. In the past few days 200 rescue workers have been buried by mudslides.

For more coverage on landslides related to the earthquake, I recommend Dave’s Landslide Blog. Geology.com also has very comprehensive coverage as well. (AFP Photo)

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China Earthquake Coverage

May 13, 2008 rockman Comments Off

The regular news media as well as the geo-blogosphere are all abuzz about Monday’s 7.9 magnitude earthquake in central China. Official death toll is at 12,000 right now and that’s in Sichuan Province alone. My guess is that number will swell substantially in the coming days. If you haven’t seen photos and video yet, they are absolutely gut-wrenching. My heart and prayers go out to the victims of this disaster. (Photo by Liu Hai, AP)

Several geo-bloggers have posts about the earthquake. Harold Asmis of Ontario-GeoFish describes the earthquake as a "big valley-thrust earthquake" or what he calls the "Fist of God". Dave’s Landslide Blog has started compiling reports of landslides related to the earthquake in this landslide prone region of China. And here is the USGS info on the earthquake.

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New Study Shows Odds High for Big California Quakes

April 15, 2008 rockman Comments Off

Released: 4/14/2008 12:02:15 PM

California has more than a 99% chance of having a magnitude 6.7 or larger earthquake within the next 30 years, according scientists using a new model to determine the probability of big quakes.

The likelihood of a major quake of magnitude 7.5 or greater in the next 30 years is 46%-and such a quake is most likely to occur in the southern half of the state.

[Editor] At Left: Figure 1. The colors on this California map represent the UCERF probabilities of having a nearby earthquake rupture (within 3 or 4 miles) of magnitude 6.7 or larger in the next 30 years. As shown in the table, the chance of having such an event somewhere in California exceeds 99%. The 30-year probability of an even more powerful quake of magnitude 7.5 or larger is about 46%. [/Editor]

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Geologic Hazard Photos

February 28, 2008 rockman Comments Off

The National Geodetic Data Center (NGDC) of NOAA has an online collection of photos of various geologic hazards. Many of the photos are from older sets of 35mm slides that have been digitized. They are free to use provided you credit the photographer and the NGDC as the source. The would be really useful for educators and for powerpoint presentations. The only drawback is that they are in TIF format and some of them could use some retouching. (Photo by University of Colorado, made available by NOAA/NGDC)

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Series of Articles on Seismic Analysis

February 19, 2008 rockman Comments Off

I had an earthquake engineering course in my geological engineering undergraduate program, and an excellent teacher, but man, the math gave me fits! Well, apparently my time has finally come to make the effort to understand it again. A retired Canadian geophysicist/engineer is writing a series of articles on seismic analysis. Read more… (Photo by trochee)

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Anniversary of Loma Prieta Earthquake – USGS Warns of Hayward Fault

November 1, 2007 rockman Comments Off

October 17 was the 18th anniversary of the 6.9 magnitude Loma Prieta earthquake that struck the Bay area. But a recent story by the Bay Area’s local ABC affiliate, ABC7, chose to focus on another earthquake, a 1868 earthquake of about the same magnitude that occurred on the Hayward Fault. According to the USGS, the Hayward Fault has a return period of about 140-years and "It’s the most heavily urbanized fault in the U.S. and it’s just waiting to go off…" Next year will be the 140-th anniversary of the last earthquake on the Hayward Fault. At some point it has the potential to be a very bad earthquake there. More after the break. (Photo by sanbeiji)

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Indonesia to Build Monumental Suspension Bridge in Ring of Fire

October 27, 2007 rockman Comments Off

Indonesia is planning to build what will be the World’s longest suspension bridge to link up its two main islands of Java and Sumatra. The total length will over 30-km with a (max?) height of 70-m so ships can pass underneath. The catch is that the bridge will be located on the Pacific Ring of Fire, the boundary between the Asian and Australian tectonic plates and one of the most seismically and volcanically active areas in the world. There have been several recent earthquakes greater than magnitude 7, not to mention the earthquake that caused the 2004 tsunami. The bridge will be built to withstand a magnitude 9 earthquake. Oh, and in case the seismic concerns weren’t great enough, the bridge will pass within 50-km of the volcano Krakatoa. The estimated cost of the bridge is $12 billion ($AU?). Credit to Geology.com for the story.

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Geologists Recover Pieces of San Andreas Fault from 2 Miles Deep

October 7, 2007 rockman Comments Off

As a follow up to a previous post, the San Andreas Fault Observatory at Depth (SAFOD) team has announced that they have successfully completed their drilling and obtained cores of the San Andreas Fault at depths in excess of 2 miles below the surface. The zone of interest is approximately 135-ft in length. The core size is 4-in diameter. They have cemented in a 7-in casing and the next phase of the project will be to perforate the casing within the fault and install monitoring equipment consisting of seismometers, accelerometers, tiltmeters and a fluid pressure transducer. Read on for more info and links. (Image credit: EarthScope / NSF)

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Japan Quake Kills 9, Effects Nuclear Plant

July 19, 2007 rockman Comments Off

A magnitude 6.8 earthquake struck Japan on 7/16/07, killing 9 and injuring more than 150. The hardest hit areas were near the town of Kashiwazaki, northwest of Tokyo. It triggered mudslides in the town that was already effected by a Typhoon several days before. One of the most newsworthy things about this earthquake is the damage to and minor leakage of radioactive waste and coolant from the world’s largest nuclear power plant in Kashiwazaki. Read on for links and video. (Photo by Kazuhiro Nogi, AFP – Getty Images)

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