{"id":194,"date":"2014-06-13T19:41:10","date_gmt":"2014-06-13T19:41:10","guid":{"rendered":"http:\/\/opentextbc.ca\/geography\/?post_type=chapter&#038;p=194"},"modified":"2014-08-29T14:23:21","modified_gmt":"2014-08-29T21:23:21","slug":"9-6-case-studies","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/geography\/chapter\/9-6-case-studies\/","title":{"raw":"Case Study 1: 1965 Hope Slide","rendered":"Case Study 1: 1965 Hope Slide"},"content":{"raw":"A <strong>landslide<\/strong> is the general term that describes the movement of\u00a0rock, soil and other debris down a slope as a result of\u00a0gravitational pull.\u00a0Landslides are most likely to\u00a0occur\u00a0in mountainous regions but may occur on any slope.\r\n\r\nThere are many factors that can contribute to the likelihood of a landslide, including\u00a0geological causes such as weak or sensitive materials, morphological causes such as tectonic plate shifting or soil erosion, and human causes\u00a0such as deforestation, water leakage, imposed vibrations or excavation.\r\n\r\nOne of the most tragic landslides in Canadian history was the Hope Slide, which occurred at 7 a.m. on January 9, 1965,\u00a0in the Nicolum Valley in the Cascade Mountains near Hope, British Columbia.[footnote]This Week in BC History video can be viewed at https:\/\/www.youtube.com\/watch?v=Aigd-_En5z0[\/footnote]\r\n\r\n<iframe src=\"\/\/www.youtube.com\/embed\/Aigd-_En5z0?rel=0\" width=\"700\" height=\"525\" allowfullscreen=\"allowfullscreen\"><\/iframe>\r\n\r\n&nbsp;\r\n\r\n[caption id=\"attachment_190\" align=\"aligncenter\" width=\"400\"]<a href=\"http:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Screen_Shot_2014-06-12_at_8.59_.58_AM_-e1406241804343.png\"><img class=\"wp-image-190\" alt=\"Figure 1. Hope Slide Location\" src=\"http:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Screen_Shot_2014-06-12_at_8.59_.58_AM_-e1406241804343.png\" height=\"327\" width=\"400\" \/><\/a> Figure 8.9 Location of Hope Slide[\/caption]\r\n\r\nShortly before\u00a0the landslide, a small avalanche (different from a landslide in that an avalanche is made up of moving snow, not rock or sediment) occurred on a stretch of the Hope-Princeton Highway below Johnson Peak, approximately 150 kilometres from\u00a0Vancouver, which\u00a0forced four people to stop their vehicles. While they were waiting for the clearing crews, a second landslide occurred.\r\n\r\nThe landslide buried the vehicles and the occupants, and all four people died\u00a0under 47 million cubic metres of pulverized rock, mud and debris that fell down\u00a0the 2,000-metre mountainside. This mass of debris completely displaced the water and mud in Outram Lake with incredible force, throwing it against the opposite side of the valley, wiping all vegetation and trees down to the bare rock, then splashing it\u00a0back up the original (now bare) slope before settling.\r\n\r\nRecent research shows that these impacts against the opposite valley sides produced the seismic signatures interpreted as earthquakes.\r\n\r\n[caption id=\"attachment_191\" align=\"aligncenter\" width=\"400\"]<a href=\"http:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Hope_slide-e1406241761321.jpg\"><img class=\"wp-image-191\" alt=\"Figure 2. Hope Slide, mountain scare is clearly visible from the side. \" src=\"http:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Hope_slide-e1406241761321.jpg\" height=\"300\" width=\"400\" \/><\/a> Figure 8.10 Hope Slide; mountain scare is clearly visible from the side[\/caption]\r\n\r\nThe landslide was caused by the presence of pre-existing tectonic structures (faults and shear zones) within the southwestern slope of Johnson Ridge. The lower parts of the slide scar are underlain by <strong class=\"Bold\">felsite sheets <\/strong>(which may have failed first) while the upper parts of the slide scar are underlain by highly jointed <strong class=\"Bold\">Paleozoic greenstone<\/strong> beds. Ongoing weathering and tectonic activity weakened the slide mass to the point where it had reached limiting equilibrium.\r\n\r\nAlthough we know the cause of the landslide, it remains unclear what the actual trigger was. A published analysis of seismograph records from January 9, 1965, suggested that the Hope Slide probably occurred as two rock avalanches separated by about 3 hours.\r\n\r\nChanges in groundwater condition are often a trigger for landslides, though are not thought to have played a role in the Hope Slide as the slide occurred during a protracted period of sub-zero temperatures in the winter. Weather records for the 25 days prior to the slide indicate that the temperature was much colder than normal, with\u00a0the average daily temperature not exceeding 0\u00ba C, and on most days it was below -10\u00ba C (Earle, 2006). Some have suggested that freezing of seepage exit points may have caused an increase in water pressure at the toe of the slide. It is also suggested that progressive long-term deformation of the slopes of the southwest flanks of Johnson Peak caused the stability of the slope to deteriorate. We can conclude\u00a0that the Hope Slide was the catastrophic result of very long term non-episodic mountain slope deformation.\r\n\r\nSince the landslide, the highway has been rerouted around and over the base of the slide's debris field 55 metres above the original ground level on the other side of valley. As a result of the slide, the mountainside remains bare rock, without significant growth of trees or other large vegetation. Visitors to the region can view the scar of the landslide along Highway 3 at a viewpoint.\r\n<h3>Attributions<\/h3>\r\n<ul>\r\n\t<li><strong>Figure 8.9<\/strong> Hope Slide location (<a href=\"http:\/\/wikimapia.org\/#lang=en&amp;lat=49.302404&amp;lon=-121.180916&amp;z=13&amp;m=b&amp;show=\/7296\/The-Hope-Slide\" target=\"_blank\">http:\/\/wikimapia.org\/#lang=en&amp;lat=49.302404&amp;lon=-121.180916&amp;z=13&amp;m=b&amp;show=\/7296\/The-Hope-Slide<\/a>) by Wikimapia (http:\/\/wikimapia.org) licensed under CC BY SA 2.0 <a href=\"\/\/creativecommons.org\/licenses\/by-sa\/2.0\/ca\/\" target=\"_blank\">(http:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/ca\/<\/a>)<\/li>\r\n\t<li><strong>Figure 8.10<\/strong> Hope Slide; mountain scare is clearly visible from the side.\u00a0 Hope Slide (<a href=\"http:\/\/en.wikipedia.org\/wiki\/Hope_Slide\" target=\"_blank\">http:\/\/en.wikipedia.org\/wiki\/Hope_Slide<\/a>) by Fawcett5 (<a href=\"http:\/\/en.wikipedia.org\/wiki\/User:Fawcett5\" target=\"_blank\">http:\/\/en.wikipedia.org\/wiki\/User:Fawcett5<\/a>) is in the Public Domain.<\/li>\r\n<\/ul>","rendered":"<p>A <strong>landslide<\/strong> is the general term that describes the movement of\u00a0rock, soil and other debris down a slope as a result of\u00a0gravitational pull.\u00a0Landslides are most likely to\u00a0occur\u00a0in mountainous regions but may occur on any slope.<\/p>\n<p>There are many factors that can contribute to the likelihood of a landslide, including\u00a0geological causes such as weak or sensitive materials, morphological causes such as tectonic plate shifting or soil erosion, and human causes\u00a0such as deforestation, water leakage, imposed vibrations or excavation.<\/p>\n<p>One of the most tragic landslides in Canadian history was the Hope Slide, which occurred at 7 a.m. on January 9, 1965,\u00a0in the Nicolum Valley in the Cascade Mountains near Hope, British Columbia.<a class=\"footnote\" title=\"This Week in BC History video can be viewed at https:\/\/www.youtube.com\/watch?v=Aigd-_En5z0\" id=\"return-footnote-194-1\" href=\"#footnote-194-1\" aria-label=\"Footnote 1\"><sup class=\"footnote\">[1]<\/sup><\/a><\/p>\n<p><iframe loading=\"lazy\" src=\"\/\/www.youtube.com\/embed\/Aigd-_En5z0?rel=0\" width=\"700\" height=\"525\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_190\" aria-describedby=\"caption-attachment-190\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><a href=\"http:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Screen_Shot_2014-06-12_at_8.59_.58_AM_-e1406241804343.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-190\" alt=\"Figure 1. Hope Slide Location\" src=\"http:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Screen_Shot_2014-06-12_at_8.59_.58_AM_-e1406241804343.png\" height=\"327\" width=\"400\" srcset=\"https:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Screen_Shot_2014-06-12_at_8.59_.58_AM_-e1406241804343.png 661w, https:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Screen_Shot_2014-06-12_at_8.59_.58_AM_-e1406241804343-300x245.png 300w, https:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Screen_Shot_2014-06-12_at_8.59_.58_AM_-e1406241804343-65x53.png 65w, https:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Screen_Shot_2014-06-12_at_8.59_.58_AM_-e1406241804343-225x184.png 225w, https:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Screen_Shot_2014-06-12_at_8.59_.58_AM_-e1406241804343-350x286.png 350w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><\/a><figcaption id=\"caption-attachment-190\" class=\"wp-caption-text\">Figure 8.9 Location of Hope Slide<\/figcaption><\/figure>\n<p>Shortly before\u00a0the landslide, a small avalanche (different from a landslide in that an avalanche is made up of moving snow, not rock or sediment) occurred on a stretch of the Hope-Princeton Highway below Johnson Peak, approximately 150 kilometres from\u00a0Vancouver, which\u00a0forced four people to stop their vehicles. While they were waiting for the clearing crews, a second landslide occurred.<\/p>\n<p>The landslide buried the vehicles and the occupants, and all four people died\u00a0under 47 million cubic metres of pulverized rock, mud and debris that fell down\u00a0the 2,000-metre mountainside. This mass of debris completely displaced the water and mud in Outram Lake with incredible force, throwing it against the opposite side of the valley, wiping all vegetation and trees down to the bare rock, then splashing it\u00a0back up the original (now bare) slope before settling.<\/p>\n<p>Recent research shows that these impacts against the opposite valley sides produced the seismic signatures interpreted as earthquakes.<\/p>\n<figure id=\"attachment_191\" aria-describedby=\"caption-attachment-191\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><a href=\"http:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Hope_slide-e1406241761321.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-191\" alt=\"Figure 2. Hope Slide, mountain scare is clearly visible from the side.\" src=\"http:\/\/opentextbc.ca\/geography\/wp-content\/uploads\/sites\/34\/2014\/06\/Hope_slide-e1406241761321.jpg\" height=\"300\" width=\"400\" \/><\/a><figcaption id=\"caption-attachment-191\" class=\"wp-caption-text\">Figure 8.10 Hope Slide; mountain scare is clearly visible from the side<\/figcaption><\/figure>\n<p>The landslide was caused by the presence of pre-existing tectonic structures (faults and shear zones) within the southwestern slope of Johnson Ridge. The lower parts of the slide scar are underlain by <strong class=\"Bold\">felsite sheets <\/strong>(which may have failed first) while the upper parts of the slide scar are underlain by highly jointed <strong class=\"Bold\">Paleozoic greenstone<\/strong> beds. Ongoing weathering and tectonic activity weakened the slide mass to the point where it had reached limiting equilibrium.<\/p>\n<p>Although we know the cause of the landslide, it remains unclear what the actual trigger was. A published analysis of seismograph records from January 9, 1965, suggested that the Hope Slide probably occurred as two rock avalanches separated by about 3 hours.<\/p>\n<p>Changes in groundwater condition are often a trigger for landslides, though are not thought to have played a role in the Hope Slide as the slide occurred during a protracted period of sub-zero temperatures in the winter. Weather records for the 25 days prior to the slide indicate that the temperature was much colder than normal, with\u00a0the average daily temperature not exceeding 0\u00ba C, and on most days it was below -10\u00ba C (Earle, 2006). Some have suggested that freezing of seepage exit points may have caused an increase in water pressure at the toe of the slide. It is also suggested that progressive long-term deformation of the slopes of the southwest flanks of Johnson Peak caused the stability of the slope to deteriorate. We can conclude\u00a0that the Hope Slide was the catastrophic result of very long term non-episodic mountain slope deformation.<\/p>\n<p>Since the landslide, the highway has been rerouted around and over the base of the slide&#8217;s debris field 55 metres above the original ground level on the other side of valley. As a result of the slide, the mountainside remains bare rock, without significant growth of trees or other large vegetation. Visitors to the region can view the scar of the landslide along Highway 3 at a viewpoint.<\/p>\n<h3>Attributions<\/h3>\n<ul>\n<li><strong>Figure 8.9<\/strong> Hope Slide location (<a href=\"http:\/\/wikimapia.org\/#lang=en&amp;lat=49.302404&amp;lon=-121.180916&amp;z=13&amp;m=b&amp;show=\/7296\/The-Hope-Slide\" target=\"_blank\">http:\/\/wikimapia.org\/#lang=en&amp;lat=49.302404&amp;lon=-121.180916&amp;z=13&amp;m=b&amp;show=\/7296\/The-Hope-Slide<\/a>) by Wikimapia (http:\/\/wikimapia.org) licensed under CC BY SA 2.0 <a href=\"\/\/creativecommons.org\/licenses\/by-sa\/2.0\/ca\/\" target=\"_blank\">(http:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/ca\/<\/a>)<\/li>\n<li><strong>Figure 8.10<\/strong> Hope Slide; mountain scare is clearly visible from the side.\u00a0 Hope Slide (<a href=\"http:\/\/en.wikipedia.org\/wiki\/Hope_Slide\" target=\"_blank\">http:\/\/en.wikipedia.org\/wiki\/Hope_Slide<\/a>) by Fawcett5 (<a href=\"http:\/\/en.wikipedia.org\/wiki\/User:Fawcett5\" target=\"_blank\">http:\/\/en.wikipedia.org\/wiki\/User:Fawcett5<\/a>) is in the Public Domain.<\/li>\n<\/ul>\n<hr class=\"before-footnotes clear\" \/><div class=\"footnotes\"><ol><li id=\"footnote-194-1\">This Week in BC History video can be viewed at https:\/\/www.youtube.com\/watch?v=Aigd-_En5z0 <a href=\"#return-footnote-194-1\" class=\"return-footnote\" aria-label=\"Return to footnote 1\">&crarr;<\/a><\/li><\/ol><\/div>","protected":false},"author":37,"menu_order":5,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-194","chapter","type-chapter","status-publish","hentry"],"part":273,"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/pressbooks\/v2\/chapters\/194","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/wp\/v2\/users\/37"}],"version-history":[{"count":21,"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/pressbooks\/v2\/chapters\/194\/revisions"}],"predecessor-version":[{"id":834,"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/pressbooks\/v2\/chapters\/194\/revisions\/834"}],"part":[{"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/pressbooks\/v2\/parts\/273"}],"metadata":[{"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/pressbooks\/v2\/chapters\/194\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/wp\/v2\/media?parent=194"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/pressbooks\/v2\/chapter-type?post=194"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/wp\/v2\/contributor?post=194"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/geography\/wp-json\/wp\/v2\/license?post=194"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}