{"id":15502,"date":"2015-07-15T07:19:25","date_gmt":"2015-07-15T07:19:25","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=15502"},"modified":"2015-07-15T07:19:25","modified_gmt":"2015-07-15T07:19:25","slug":"judgement-cliff-rock-avalanche","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2015\/07\/15\/judgement-cliff-rock-avalanche\/","title":{"rendered":"The Judgement Cliff Rock Avalanche in Jamaica"},"content":{"rendered":"
The Judgement Cliff Rock Avalanche in Jamaica<\/h5>\n

At 11:43 am on 7th June 1692 an Mw=7.5 earthquake struck the town of Port Royal in Jamaica<\/a>, killing an estimated 2000 people.\u00a0 The greatest impacts of the earthquake occurred in the town of Port Royal itself, in which there appears to have been a combination of a submarine landslide that removed 33 hectares of the town (this is sometimes interpreted as a liquefaction event, although this seems unlikely to me) and a tsunami (which could have been related to the landslide given the nature of the strike-slip faulting in Jamaica – I would not expect this earthquake to have been tsunamigenic in its own right).<\/p>\n

Inland, the earthquake is associated with a large earthquake, known now at the Judgement Cliff Rock Avalanche<\/a>.\u00a0 Strangely, it is a little unclear as to whether the landslide was triggered by the earthquake or by heavy rainfall a few days later (but it seems to me that a seismic origin is most likely given the depth of the shear surface).\u00a0 The landslide is very large – Maharaj (1994)<\/a> provides a detailed description, estimating that it has a volume of between 131 and 181 million cubic metres, and extended over 440 metres vertically and 1763 metres horizontally. The landslide is very clear in contemporary photographs:<\/p>\n

\"Judgement<\/a>

Jamaica Observer<\/a><\/p><\/div>\n

.<\/p>\n

And on Google Earth images, even 320 years after the event:<\/p>\n

\"Judgement<\/a>

The Judgement Cliff Rock Avalanche on Google Earth<\/p><\/div>\n

.<\/p>\n

Maharaj (1994)<\/a> describes a landslide body consists of highly fragmented and disrupted limestone fragments and chert nodules, suggesting that the Judgement Cliff rock avalanche was very dynamic.\u00a0 The runout distance is quite large – the H\/L (height \/ length) index is 0.25, implying a flow-type mechanism.\u00a0 Indeed as such this is an unusually mobile rock avalanche, comparable with for example, the Elm landslide in the Alps<\/a>.\u00a0 As such this landslide would probably benefit from a more detailed investigation.<\/p>\n

The Judgement Cliff Rock Avalanche was reported at the time to have killed at least 19 people.\u00a0 Thus, for example, a report compiled in 1809 on the basis of eye-witness accounts suggested that:<\/p>\n

“a great mountain split and fell into the level land and covered several settlements and destroyed 19 white people” (Maharaj 1994, p. 243).<\/p><\/blockquote>\n

My interpretation is that the loss of life would have been rather higher, given that the account only appears to be concerned about the colonial settlers.<\/p>\n

There is a nice account of the oral history of the landslide and the mythology that is associated with it in the Jamaica Observer<\/a> from a few years ago.<\/p>\n

Reference<\/h5>\n

Maharaj. R.J. 1994. The mprphology, geometry, and kinematics of Judgement Cliff Rock Avalanche, Blue Mountains, Jamaica, West Indies.\u00a0 Quarterly Journal of Engineering Geology,<\/em><\/a> 27<\/strong>, 243-56.<\/p>\n","protected":false},"excerpt":{"rendered":"

In June 1692 the Port Royal earthquake triggered the Judgement Cliff Rock Avalanche in Jamaica, killing at least 19 people <\/p>\n","protected":false},"author":22,"featured_media":15514,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[544],"tags":[173,23,469,883,306],"class_list":["post-15502","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-review-of-a-paper","tag-caribbean","tag-earthquake","tag-featured","tag-jamaica","tag-rock-avalanche"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/15502","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/users\/22"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/comments?post=15502"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/15502\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/15514"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=15502"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=15502"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=15502"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}