Many thanks to reader Ripendra for alerting me to the following, and indeed for doing nearly all the work for this post. The 14th June 2008 earthquake in Japan is known to have triggered a number of landslides, as per earlier posts, but the most notable appears to have occurred at Aratozawa Dam in Miyagi prefecture. The Aratozawa Dam (Figure 1) is a rockfill dam used for flood control, irrigation …

At 08:43:46 local time on Saturday 14th June 2008 a magnitude Mw=6.8 (USGS initial estimate) struck eastern Honshu in Japan. Although this earthquake (now being called the Iwate-Miyagi Inland Earthquake) was not particularly large, it occurred at a shallow depth (10 km) below an area that is quite mountainous. This is an areas that is very landslide prone anyway, being subject to active tectonic processes and frequent typhoon rainfall events. …

At 08:43:46 local time on Saturday 14th June 2008 a magnitude Mw=6.8 (USGS initial estimate) struck eastern Honshu in Japan. Although this earthquake (now being called the Iwate-Miyagi Inland Earthquake) was not particularly large, it occurred at a shallow depth (10 km) below an area that is quite mountainous. This is an areas that is very landslide prone anyway, being subject to active tectonic processes and frequent typhoon rainfall events. …

Now that the Tangjiashan crisis is over, it is clearly time to move on to other things. I will posta retrospective on that event when the dust has settled. For now I think we should allow the Chinese to bask in the success of their achievement. To change the topic, I thought it would be interesting to post an analysis that I did a couple of years ago. The analysis …

Two days ago I posted this picture AP image of the channel at Tangjiashan: AP image captioned: Water from the Tangjiashan “quake lake” flows down a landslide site in the quake-devastated Mianyang City, southwest China’s Sichuan Province. Today, the following Reuters image has been released, apparently showing the same location: Reuters image entitled: Water flows through a sluice channel of the Tangjiashan quake lake in Tangjiashan, Sichuan Province June 8, …

I thought that this would be a good time to review the situation with Tangjiashan now that water has been flowing for over a day. 1. Water flow is now apparently about 21.5 cumecs – up from 10 cumecs at about the same time yesterday. This is still not enough to balance inflow, so the lake level continues to rise. Of course as the lake level increases the rate of …

Xinhua is now reporting that the discharge in the sluice has now reached 40 cubic metres per second. This means that it is less than half that required to balance inflow at the current rate (c. 100 cubic metres per second). So far at least the channel is apparently stable. The same report indicates that the lake volume is now 229.5 million cubic metres. This is good news. The lake …

Various media sources are reporting that water began to flow through the channel at Tangjiashan today. For example, Reuters is reporting that:“Chinese troops began easing pressure on a dangerously swollen “quake lake” on Saturday, with water gushing into a man-made sluice in an operation monitored by satellite.” The dam and channel now has to survive two critical phases. The first lies in the next day or two, with increasing volumes …

Xinhua is now reporting that the flow through the sluice has now been delayed through the use of a 60 cm high temporary dam (see below). This is an interesting development – I wonder why they have decided to do this at this late stage. Delaying the flow has a risk associated with it as the body of water will be larger, and thus the flood is potentially more damaging. …

Xinhua has reported in the last 20 minutes that:“Water level of China’s main quake lake Tangjiashan climbed to the critical point of 740 meters on a sluice channel at 0:00 a.m. Saturday, but the long-awaited drainage hasn’t started yet.” Given that we know that it has been raining in the area this afternoon, over-topping must be about to start. Hold onto your hats…! And can I just say good luck …