13 January 2009
Costa Rica Earthquake – the aftermath
Posted by Dave Petley
I thought a brief follow up email to my previous posts about the Costa Rica earthquake would be useful now that we are five days post the event. So what do we now know?
Well, first the final death toll is likely to be about 40, most of whom were killed by landslides. Officially, as of today, 19 bodies have been recovered and 21 more are buried under landslide debris. It is possible that there is a small number of addition casualties under collapsed slopes. Landslides continue to occur during aftershocks and there is growing concern about the potential for future slides (see image below). Initial estimates of the damage are $100 million. In a country with a GDP of $26 billion, this is a huge amount (in comparison, the GDP of the UK is $2.13 trillion, meaning that the equivalent loss in terms of GDP would be $8.2 billion). Estimates are that the earthquake destroyed 518 houses, triggered the loss of 16 miles of road and collapsed eight bridges. Of course there will also be a substantial hit to tourism, which is vital in this area.
In terms of landslides, the emergency management office has indicated that the earthquake triggered more than 246 landslides. Repair of roads damaged by the landslides is expected to cost $15 million (see image below).
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
Is there any information about how many post-earthquake landslides occurred ? I would like to know the reason ( or mechanism) why slopes which had survived the strong ground motion of main shock collapsed after few days.
K.A., the official number of landslides in the earthquake is 246, although I suspect that the reality is that this is the number that have caused damage in reality. The true number is probably higher. I doubt that anyone has collated information about what has happened since in any systematic way. Post event landslides happen for four reasons on the whole:1. Some slopes are left in an unstable state and collapse through time (delayed elevation of pore pressures may also be a factor);2. Some slopes fail due to aftershock activity;3. Some slopes fail in post event rainfall;4. Some slopes collapse due to recovery and reconstruction operations (especially as roads are being reopened)In the case of Costa Rica, it is clear that the weather since the earthquake has been wet (which may have triggered some slides) and there have been many aftershocks. I suspect that this is the main explanation.
I was in the earthquake in Costa Rica on the 8th. my wife and I were in Zarcero (I think thats how its spelled). The earth quake movement itself was felt and timed by us for at lest 8 minutes. The main shake was probably arounf 1 minute. We were in a restaurant that was up on stilts and the movement at the first 5 secounds was pretty intense followed by a swaying that seemed to me to be pretty gentle. On our ride back to San Jose we did not see any damage caused by the quake. We did however avoid large bridges. In San Jose itself we saw mainly cracks in building and it seemed the whole population of the downtown area was on the street. As far as landslides we did not see any. The terrain however to Poas volcano is very rugged and the main road up the volcano is built with very litle guard rails and there are many area where the road is right at the edge of very large drops. This is probably the biggest factor for so much damge to the road system in the area. i hope this helped. Jim Johnson
We were at the La Paz Waterfall Gardens, the epicenter of the quake, at the time of this 6.2 equake. Fortunately it was during the dry season or else their would have been even more slides. This is a high elevation mountainous region with roads cut into mountain slopes. Please see this link below for photos and consider making a donation to help out the surround villages rebuild. Thank you, Susanhttp://www.waterfallgardens.com/quake/
Hi,I am looking for an American who resides just out of San Jose on one of the mountains (I believe on the eastern side of Costa Rica). We have been trying to reach him without luck. His name is Jack McCune and my husband is his stepson. If anyone has any info please email me at [email protected] Thank you, Tammy
Thank you for the link Susan! We had been to the Peace Lodge some years ago and loved it!The hotel is still closed and it seems that some roads can’t be repaired. The road between Carrizal and Cariblanco is still closed, you can see it here:costa rica map