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Rob Parker (University of Cardiff) and Dave Petley
The Mw = 7.8 earthquake on Tuesday in Iran was the largest event in that country for about 50 years. Fortunately, the depth of the earthquake (82 km) and the low population density in the affected areas meant that loss of life was low for an event of this size. Indeed, reports suggest that only one person died in Iran, although there are reports of 40 deaths in Pakistan. This single fatality in Iran was the result of a landslide, and one of the images on the BBC reports about the earthquake also seems to show landslides:
Over the last three years or so, we have been working with our colleagues Alex Densmore and Nick Rosser, funded by the Willis Research Network, to develop a model that will allow us to make an initial assessment of landslide impacts in earthquakes. Rob recently submitted his PhD, and has now moved to a post-doctoral position at Cardiff. However, we thought that this event would be an interesting first application of the model, which has been produced through a statistical (logistic regression) analysis of spatial patterns of landslides (with areas larger than 11,000 square metres) triggered by four large earthquakes in the USA, New Zealand, Taiwan and China. The model provides a first-order prediction of the probability of hillslope failure across the region affected by seismic shaking, based on the strength of ground motions and the gradient of hillslopes. Areas likely to have experienced high levels of landslide activity are shown in red, and while areas we expect to be less affected by landslides are shown in green and then blue. Here, landslide probability has been estimated using preliminary ground motion data published by the USGS and hillslope gradients derived from the ASTER global elevation model. Read more
Yesterday I was deeply honoured to present the AQA Annual Lecture at the Geographical Association annual conference in Derby. I talked on the topic of Future Trends in Natural Hazard Losses - essentially a review of what we expect to see in the next few decades on a global basis. I started the talk by looking at recent trends, and then looked forward to what we might expect. I finished with an example of one of the mega-quakes that we fear – in this case a large earthquake in Western Nepal.
The slides are on Authorstream – you can download the Powerpoint file there – and should also appear below:
Re-blogged from Dave Petley’s Landslide Blog
Rockfall at Port Hills, Christchurch. Credit: Rob Becker
One of the legacies of the Christchurch earthquake sequence in New Zealand has been both increased levels of rockfall hazard and increased awareness of the level of hazard that predated the seismic events. The most seriously affected area is the Port Hills area to the southeast of the city, where large numbers of houses were affected by rockfalls during the earthquakes, and may more were left at risk in the aftermath. To assess the level of hazard properly, Christchurch City Council commissioned GNS Science to undertake a quantitative life risk assessment for the affected areas. This has been a huge piece of work, undertaken in the public spotlight on a very short timescale. The aim has been to generate the best possible assessment of the risk to life; this assessment can then be used as the basis for decisions on the viability of individual properties. Read more
The M=7.4 that struck just offshore western Guatemala yesterday is now believed to have killed at least 48 people, with more people thought to still be buried in the rubble. The location of the epicenter of the earthquake, as measured by the USGS, indicates that there is high ground within the area that might be expected to have suffered high peak ground accelerations (as the Google Earth perspective view below shows), indicating that landslides are likely:
Inevitably, the area affected by landslides is both remote and inaccessible in the aftermath of the earthquake, so a proper understanding of the landslides will take some time. In the meantime, there is some evidence that landslides have been a significant problem. The BBC has two images that show landslides. Read the rest of this entry »
Dr Timothy Sim with Hong Kong Polytechnic University visited Durham University to present a unique exhibition of photos by young people who lived through the 2008 Sichuan earthquake in Wenchuan, China. In this video, Dr Sim talks about the resilience of the children who survived the earthquake and tells the story behind their international photo exhibition. This video includes photos from the exhibition.
