A follow up to the Sea to Sky Highway landslide

Back on 1st August I posted about a landslide that had blocked the Sea to Sky Highway (Canadian Highway 99), which links Vancouver to Whistler, venue of the 2010 Winter Olympic Games. The road was blocked for a few days, but has now reopened.

Two sets of colleagues in Canada have very kindly provided follow ups to that post. First, Frank Baumann, who is a geotechnical engineer in Squamish has very kindly sent an image (Fig. 1) of the landslide for inclusion on the blog. This very nicely captures both the scale of the problem and the topographic setting of it.

Fig 1: Photograph (copyright Frank Baumann) of the Highway 99 (Sea to Sky Highway / Olympic Corridor) landslide in Canada.

Second, Steve Evans and Keith Delaney from the Landslide Research Programme at the University of Waterloo in Canada have very kindly provided the following explanation of the landslide, including this excellent comparison image:

Fig 1: Illustration (provided by Steve Evans and Keith Delaney from the University of Waterloo) showing the site of the 29th July 2008 landslide. The main image shows the site before the failure, the smaller image the site after. Inset is a stereographic projection plot of the failure surface and joint sets. Click on the image for a better view.

Steve and Keith write:
"The site of the July 29^th 2008 Sea to Sky rockfall/rockslide was examined in 1997. The main photograph in Figure 2 shows the site at that time. The photo at the lower right of Figure 1 was taken soon after the 2008 event by Canadian Press. The slope consists of resistant Coast Plutonic Complex granite but as seen on the 1997 photograph (and on the cover of the book “Rock Slope Engineering” by Hoek and Bray) the rock mass is characterized by more-or-less planar stress relief (sheeting) joints that dip west (downslope) towards Howe Sound (pole concentration is red dot on the stereonet in figure 2). Undercutting of the slope during construction of highway in 1958 resulted in the sheeting joints daylighting in the rock slope (pole concentration is red dot on stereonet). The location of the 2008 rockfall is known as Porteau Bluffs, they run for just under 1 km along Howe Sound (49 33 52.15N; 123 14 01.44W), and the rock slopes along this section of highway exhibit similar rock mass characteristics to those involved in the July 2008 event."

Frank Baumann has kindly also provided a couple of other images of another landslide at the north end on Highway 99 - this time an incipient failure (Figs 3 and 4). It clearly shows that there are other potential problems on this road - although it is also important to stress that, surprising though this might seem, cracks like this do not mean that collapse is imminent or even likely.

Fig 3: Photograph (copyright Frank Baumann) of an ongoing failure on Highway 99 in Canada

Fig 4: Photograph (copyright Frank Baumann) of an ongoing failure on Highway 99 in Canada

Thanks to Frank, Steve and Keith for their contributions to this - I very much appreciate their input.

Serious landslide in Indian Kashmir - at least 20 people killed

Updated: It appears that May has started with a terrible rockfall in Indian Kashmir (Figure 1). Reports are still rather sketchy, but it seems that the landslide occurred in the Chatroo area Kadiyah,which is about 220 kilometers from Jammu. The rockfall which happened on a road linking Kishtwar and Islamabad, seems to have been caused by blasting. Greater Kashmir online reports:

Eyewitnesses said that the incident took place when some of the labourers were busy in blasting a hanging part of the mountain for widening of the highway this morning. Two tippers, carrying labourers working with the Border Roads Organisation, crossed the same spot from opposite sides when a large portion of the mountain slid down, burying the two tippers and men under several feet of earth.

Figure 1: Greater Kashmir online image of the 1st May landslide, showing one of the buried vehicles. The chances of survival appear to be very limited.

Reports vary on the number of victims, but at least 20 and maybe as many as 30 seems to be the ballpark figure. The outlook doesn't look promising for the victims judging by Figure 1. Understandably, recovery is proving difficult - Greater Kashmir online reported:

“We need to blast the large stones that cannot be moved otherwise,” Kishtwar’s additional deputy commissioner, Riyaz Ahmad Zargar, told Greater Kashmir. “It is difficult to tell how many more are trapped. Fears are that the number could be in excess of 20. Exact details of the causalities can be ascertained only when the rescue operation ends." Zargar said that screams could be heard from under the rocks and efforts were being made to rescue men who could still be alive under the debris.

In an earlier post I highlighted the danger of mountain roads to buses. In a sense these trucks were being used for the same purposes, once again with tragic consequences. Sadly of course with good supervision during construction such rockfalls can be mostly avoided.

Landslides and buses

A nasty landslide this week in Peru triggered some thoughts about the occurrence of landslides that kill the passngers on buses. The event that triggered these thoughts occurred on 6th February when heavy rain dislodged a boulder hit a bus and knocked it into the Tarma River in Junin Province in Peru. Seven people were killed and a further 23 were injured.

TV3 news in New Zealand had this picture of the remains of the vehicle:

Such events appear on the database quite often, so I thought it might be interesting just to look at the 2007 data to see where and when they occur. These are the bus-related landslides within the Durham database:

Date	Country	Location	Fatalities	Injuries
24/02/2007	Pakistan	Sanadhi (Paniola) village, 15 kilometres away of Rawalakot, Kashmir	15	5
12/03/2007	India	Nauliband area of the Rudraprayag district, Uttarakhand	18	32
02/04/2007	China	Pengshui, Chongqing Municipality	7	1
25/05/2007	China	Shimian to Hanyuan county in the central western city of Ya'an, Sichuan	10	14
04/07/2007	Mexico	Eloxochitlan, Puebla	32
20/08/2007	Nepal	Palpa-Tamghas road, Palpa	25
02/09/2007	India	Ghansali town in Tehri district, Uttarakhand	19	20
17/09/2007	India	Rudraprayag district, Uttarakhand	19	28
11/10/2007	India	Vishnuprayag, Chamoli district of Uttarakhand	41
20/11/2007	China	Badong county, Enshi Tujia and Miao Autonomous Prefecture in southwest Hubei	35	1
		Totals	221	101

It is clear that there is a particular problem with landslides affecting buses in mountain areas, particularly in Asia. Over 200 deaths is a very high impact indeed. The impacts occur in one of three main ways:
1. Buses being hit by landslides or by rockfalls and knocked into a river (as in the case of Peru this week)
2. Buses being buried by landslide debris (this happened in the Pakistan example)
3. Buses being affected by a human induced failure. The Badong event in China was the result of a rockfall triggered by tunnel construction.

There are occasional other factors too - in one case the accident occurred because the driver was speeding to attempt to avoid a rockfall. I suspect that no-one has ever undertaken a systematic study of bus-related landslide fatalities. This is probably an important topic.