26 July 2013
The M=6.6 earthquake in Gansu province this week killed about 100 people in a poor area of China. Gansu is earthquake-triggered landslide country – the great M=8.5 earthquake of 1920 killed between 70,000 and 200,000 people, many of them in huge seismically triggered flowslides that buried whole towns. So, even though the event this week was by comparison a small earthquake, it is unsurprising to find that landslides have been a significant issue. News from the earthquake-affected area is scarce, but the Big Picture, the photo section of Boston.com, has a wonderful gallery of images from the area. The best of these shows two spectacular flowslide failures:
Other images show the aftermath of the landslides; this one for example has blocked a road:
And this one shows a slightly strange rockfall in loess – I am now really sure how one should classify such a phenomenon:
Meanwhile, the timing of this earthquake early in the wet season was likely to generate significant post-seismic landslide issues, so it is no surprise to see news reports today of severe rainfall-induced landslides in the earthquake-affected area. Xinhua reports that it is likely that nine people have been killed in one of the landslides, in Nanyu Village, Niangniangba Township, Qinzhou District within Tianshui City administrative area, burying 13 people. A further four people are missing after another landslide, this time in Yongguang Village. Landslides will be a big problem in this area during any heavy rain this summer.