Do We Need To Look At The Risk Of A Mud Slide Or Earthquake
While we look to the south for both an earthquake and a mudslide such as the one that has just occurred in Washington state, we have trouble grasping the issue as it affects the people of central BC and the north, and yet this problem is not unique to these areas.
Just how stable are the cutbanks, or the various slopes of both the Nechako and Fraser hillsides? We do know that earth quakes can be felt in Prince George, at least two have been felt in this region over the past decade. There have also been a number of small earthquakes near Quesnel ( near the Nazko Cone) in the fall of 2007.
What would happen to the those who live along the valley of the Peace River in the event of a mud slide? We do know that the soils surrounding the river valley are very unstable in some regions.
We don't need to rush off and begin a study that might take years and millions of dollars to find that we could have a problem in the event of a catastrophe like the one which happened Washington State , or that an earthquake of severe proportions could cause havoc in our region.
Just as the office of the Auditor General is calling on government to look more closely at the issue more closely in the lower mainland , a little examination of what we might expect and what preventive measuresshould be taken, might be in order for our city and region.
I'm Meisner and that's one man's opinion.
Comments
One issue that should be examined is that of residential or commercial areas that are located at or near the bottom of hillsides.
Too often, the hillside and/or top of the hill is owned by others, or maybe the crown, therefore may eventually be subject to some sort of development. Point being, those at the bottom of the hill may not have any control of what happens beside and above them. If such development strips the trees and vegetation from the the hillside or area at the top, then in my opinion the stage is set for an eventual landslide.
The trees not only anchor the slope and the area above the slope with their root systems, they also draw ground water. Take away the trees, there is suddenly more water available to saturate the soil, and, after a while, no vigorous root system to hold it all together. Add in a few weeks of heavy rain, and you have a situation such as what befell the town of Oso, Washington. There are many such potential scenarios, when will it happen again?
metalman.
Ben, I’m more interested to know if there are any geotech type studies done on Kenny Dam on a yearly basis to determine how safe it would be in an earthquake. There’s what, 500 Km of lakes behind it, how far would the flooding go, what communities would be wiped out?
Earthfill dams are not rigid structures. They can remain viable after a small amount of deformation. Concrete dams are rigid and don’t bend. The spillway on Ootsa lake is more vulnerable to earthquake damage. If it fails, the top many feet of water would drain from the lake through a comparatively small hole.
Ben,here is a link to an excellent Guide to the Geoscape around Prince George. The Cutbanks aren’t going anywhere soon but what is interesting in the guide is the fact that the rock you see along Foothills blvd is volcanic. I read somewhere that Cranbrook hill is located on a fissure. Who cares about earthquakes! If the fissure along Cranbrook hill opens up it could lead to a rather warm day.
http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CEcQFjAD&url=http%3A%2F%2Fdpts.sd57.bc.ca%2F~gthielmann%2Fgeog12%2Fgeog12docs%2FUnit3Forces%2FGeoscapePG.pdf&ei=ZhUzU_HaL5DeyQHqtYCgDQ&usg=AFQjCNEmUNGbP4tdO8MUsrBZpyrSK1du4A&bvm=bv.63738703,d.aWc
It’s along link but it works and it leads to a PDF called GeoscapePG
I wonder what the folks in West Quesnel are thinking.Part of their neighbourhood has been sliding for years.
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