16 October 2013

Initial news of landslides from the earthquake in the Philippines yesterday and Typhoon Wipha in Japan today

Posted by Dave Petley

1. The M=7.1 earthquake on Bohol Island in the Philippines

Yesterday’s earthquake in the Philippines is now known to have killed at least 107 people.  Over the next few days, the Philippines disaster management agency, NDRRMC, will release a series of very informative reports about the costs of this event, and the casualties, but at this stage information remains quite sketchy.  However, this is most definitely landslide country, so it is likely that there will be at least some losses from this cause.  At the moment, the best information I can find is on the Earthquake-Report website, which provides some images of landslides.   A part of the area affected is the rather unusual “Chocolate Hills”, which look like this (image from here):

Chocolate Hills



The Earthquake-report blog has these images of a part of this area, suggesting that there has been some landslide damage:

Chocolate Hills after earthquake

Courtesy of @docjolt and Earthquake-report.com


These are classic earthquake-induced landslides – shallow failures eminating from the top of the slope.  However, a close up of one of these hills suggests a very interesting failure mode:

Chocolate hills localised collapse

Courtesy of Earthquake-report.com

In terms of losses, Earthquake-report.com are reporting the following:

  • The highway in Cortes particularly in Lilo-an was rendered impassable due to a landslide. A part of Cortes’ highway was also damaged.
  • Many … deaths have occurred in a collapsed hospital (Congressman Castillo Memorial Hospital at the Loon municipality on Bohol, and due to landslides.
  • In Balilihan, the Bohol Mayor, Dominisio Chatto has confirmed that 5 people died from a landslide due to the earthquake.
2. Typhoon Wipha in Japan

Meanwhile, earlier today Typhoon Wipha swept across Japan, bringing quite exceptional levels of rainfall (some areas are reported to have received over 800 mm).  Current reports suggest that at least 14 people have been killed and a further 50 people may be missing, although these numbers will change during the day.  Most of the deaths are reported to be the result of landslides, primarily on the island of Izu Oshima.  Again, information is sketchy at the moment about this event.  The Japan News suggests that the number missing is 43.  There is little doubt that much of the loss has been caused by landslides- this image (from RT) very clearly shows a landslide event:

Wipha landslide



Some if the things reported as landslides appear to be very complex events that are rather hard to interpret at this stage due to the very large ampunt of wood present, such as this one:

Wipha mudslide


We will have to wait for a few more hours to know the true story on these events, but landslides appear to have played a key role in both cases.