Landslide in Saint-Jude Quebec

Source: Canadian Press.  A landslide last year taken May 11, 2010

The above photo was taken a little less than a year ago in Saint-Jude Quebec.  Now there are signs that another landslide in the area may occur.  Nine families are waiting to hear if they can return to their homes, after a riverbank collapsed last Wednesday.  A large section off the Salvail River eroded and collapsed into the water.  Officials are taking precautions in order to avoid another disaster as last years landslide resulted in a family of four that died.  

So what are these signs that are predicting another landslide?

Over the past week heavy rains have caused the ground to be less stable.  The ground in the area overlies a clay seabed where water can get in between the clay particles.  Water in between clay particles = unstable.  The soil becomes weak, even worse if there are buildings providing a load on it.

It makes you wonder why homes were ever built on this clay layer in the first place.  Testing is usually done before houses are even constructed to know the types of material the foundation is going to be built upon.  These homes have probably been there a long time and testing was not available when they were being built. Now a days, homes would not be built without having lab tests done on the soil. 

Municipal and provincial officials will spend the next two months assessing the safety of the area and mitigating the erosion problem along the Salvail River.  To stabilize the shore will take six to eight weeks.  

To read the original article click here

Liquefaction

Liquefaction

"When sediments liquefy, they lose their structure and strength. During earthquake shaking, the individual grains of sand within a deposit collapse on each other. Anything built on them can sink or collapse. Picture a container of balls of slightly different sizes–baseballs, golfballs, marbles. If they were transported by water into the container and then deposited, they would settle with spaces between them. Some of the spaces would be filled with water, some with air. When you shake the container, the balls settle against each other, and the water and air are forced to the surface. That is exactly what happens in a sediment-filled valley. The valley is a large ‘container’ holding gazillions of ‘balls’ or grains of sand. Shaking the container simulates an earthquake" (Science Views).

Source: Science Views

This video shows how and why houses get damaged or collapse during an earthquake in a seemingly stable geologic environment.
The following observations were made:

• The water works its way to the surface, flooding the area around the houses,
• The "houses" start leaning over and sinking into the sand, and
• The volume of the sand decreases by a small amount.

Another Aftershock for Japan

Areas are still flooded from the tsunami near Sendai, Japan and yet another aftershock it the east coast of Japan, 40 miles from Sendai, knocking out the power in the northern part of the country on Thursday morning.  It was orginally measured to be a magnitude 7.4 but was downgraded by the U.S. Geological Survey in Golden to be a magnitude 7.1 aftershock of the 8.9 earthquake.  It is the strongest aftershock since several were recorded on March 11.  Another two were killed as a result of the aftershock and over a 100 injuries were reported.  A tsunami warning was issued following the quake, but was then taken off and announced that there was no tsunami threat to Hawaii.

The operator of the Fukushima nuclear power plant said there was no sign that any more damage was done.  The plants spent fuel pools lost cooling capacity briefly when the power went down, but resumed shortly after just the way it was supposed to work.  There is no evidence of any radiation to have leaked so far.  It is constantly being monitored right now.  Japan cannot afforded to have more destruction to its nuclear power plant.

I-70 High Maintenance

Close to home, I-70 near Georgetown was closed this last Tuesday due to mitigation of rockfall hazard.  Rock scalers were working for seven hours prying unstable boulders from the rock outcropping 300 feet above the highway near Georgetown.  To loosen the rock, the Colorado Department of Transportation (CDOT) used high-pressure airbags as well as other devices.  The boulders were caught in netting that was strung across the slope of the Georgetown Grade.  Georgetown Grade gets a significant amount of attention because of the heavy traffic volumes on I-70 below and it has an especially high slope that can send rocks down a long distance, building energy and momentum as it goes.

Source:Denver Post

For a short video that shows rocks being scaled click here

Scaling is done periodically to help reduce the risk of rockfall coming onto the highway.  By closing the highway and prying these boulders out, they will no longer be taunting I-70 commuters below.  About 30,000 motorists drive along I-70 at Georgetown Hill every day.  In 2003, a commuter was killed when a boulder crashed into his windshield.

After working on the site, CDOT announced that another rockfall mitigation technique may need to be done in the coming weeks.  Anchoring boulders may be done, if a solid section of the slope can be found.  This would mean another lengthly closure of I-70.

CDOT has placed netting along the slope face.  The goal of these nets is to progressively slow down falling rocks by letting them slip through the netting and roll to the next fence.  The rocks will loose energy this way each time they hit the netting.

The full article can be find here: I-70 reopens near Georgetown; intermittent closures planned Wednesday

China Maps Active Faults

The Chinese government has announced it launched a campaign to map its country's active faults as a result of the strong earthquakes in Japan and Myanmar.

The reason for this being that earthquakes mostly occur on or near active faults.  China has faults that run tens to thousands of kilometers in length.

The CEA Institute of Geophysics has said that China is working on a new seismic map which would mark the different regions by the risk of a quake.  They have said the map will be finished this year.  Based on this new map, the government will have specific requirements for buildings and other facilities across the country.

You may be wondering if Japan was pursuing mapping their active faults within their own country?  Japan has already mapped the seismic risk of different regions. They are considered to be very well prepared for earthquake activity with codes for buildings and other infrastructure already in place.  However, I still find it quite scary that if an earthquake happens at the country's capital of Tokyo, it will hit one of the most densely populated city in the world.

It is encouraging that China is taking action to be better prepared for earthquakes in their country.

California updates plans for tsunami danger

Damages along the Californian coast have reached up to $50 million.

Scientists at the California Geological Survey (CGS) are visiting every port city along California's coast to detail the affects of the tsunami that hit the coast as a result of the March 11 earthquake in Japan.


Rick Wilson, and engineering geologist for the California Geological Survey has said, the CGS is now planning maps to help land-use planners assess hazards to buildings near shores and harbors as well as provide a guide to danger zones where new construction might be avoided.  The new maps will not be ready for a year or two.  The maps are primarily based on a worst case scenario of a 9.2 magnitude earthquake in the Aleutian Islands (Alaska).

Read more: http://www.sfgate.com/cgi-bin/article.cgi?=/c/a/2011/03/21/BAR51IG6NE.DTL#ixzz1HSC1rchY

New evacuations plans are also being developed for future tsunamis.

It is good to know that we are learning from this disastrous event so that we can be better prepared in the future.

We're Sinking....

Foundation and walls cracking....water leaking through windows....

These are a few signs that people whose houses are built on sinkholes are seeing in Florida.  The land below their houses in sinking.  Some home owners are saying that their house will sink in before it will be fixed.  There is a major debate going the the Florida legislature right now to find out when insurance companies should pay for sinkhole damage.  For more information about the insurance companies seeking legislation to reduce sinkhole claims click here.

What is a sinkhole?
A sinkhole is a hole or depression in the earth's surface often associated with glacial terrain.  Sinkholes can vary in size from about 3 meters to 600 meters.  They can form gradually or can occur suddenly in rocks that naturally be dissolved by water circulating through them.  This creates voids in the rock that can cause the rock to collapse.  Many processes can lead to sinkholes.  Erosion, lowering the level of groundwater, or the collapsing of a cave can all lead to the formation of sinkholes.

Check out this video catching the some of a sinkhole collapsing in Texas in 2008.