Landslides at Donghekou, Ciban and Kangle in the Sichuan Earthquake

Reports and images are now emerging of the complete burial of three villages, Donghekou, Ciban and Kangle, located on the Qingzhu river in Sichuan Provinc as a result of (separate) landslides in the Sichuan Earthquake. In particular, images are now available of Doghekou, which is one of the landslides that has blocked the river upstream of Beichuan. These three landslides have together entombed an estimated 300 families, which would indicate a death toll of about 1000 people based upon an average household size of 3.32.

The Donghekou landslide appears to be very large. AP have released the following images. The caption describes this as a mountain collapse, which would seem to be appropriate for a slide of this size. Note that in at least one case the rising water levels behind the landslide dam can be seen. The hazards of this should not be under-estimated. The landslide appears to consist of very disaggregated and fragmented material, not the bouldery surface that we usually see for rock avalanches.

Caption: Survivors, bottom left and right, gather near the aftermath of a mountain collapse that swallowed up Donghekou village and two other village near Qingchuan, southwestern China's Sichuan province, Saturday, May 17, 2008. Around a hundred households and hundreds of residents were completely buried after Monday's quake.

Caption: Residents stand on the highway and view the aftermath of a mountain collapse that swallowed up Donghekou village and two other villages near Qingchuan, southwestern China's Sichuan province, Saturday, May 17, 2008. Around a hundred households and some hundreds of residents are lost, completely buried after Monday's quake.

Caption: A man is dwarfed by the aftermath of a mountain collapse landslide triggered by an earthquake that swallowed up Donghekou village and two other villages near Qingchuan, southwestern China's Sichuan province, Saturday, May 17, 2008. Around a hundred household and hundreds of residents are completely buried after Monday's quake. (AP Photo/Ng Han Guan)

Satellite imagery of the landslides in the Sichuan earthquake

Now that there is a brief weather window, satellite imagery is starting to emerge of the Sichuan Earthquake zone. At present most of these images are too low resolution to allow detection of the real damage to the buildings (which is notoriously difficult to achieve), but they are excellent for looking at landslides.

The best to date that I have seen has come from the Taiwanese Formosat-2 instrument, which is a moderately high resolution imaging system that passes over Taiwan (and thus China) on a twice daily basis (10 am and 10 pm). They have helpfully released before and after images of the Beichuan area:

(Annoted from the BBC - click for a better resolution version)

The town in the centre of the image located around the river is Beichuan. The landslides are the brown areas on the left hand image - it is clear from this that about 20% of the land mass in this area has slipped. The southern edge of the town has been hit by a big landslide (see here) that appears from this image to have spread over a large area. Worryingly, some of the rivers also appear to have been blocked in two locations by landslides. I hope that urgent works are underway to resolve this as there is a real danger of a secondary disaster when the blockages are breached. This is an absolute crisis that needs very urgent action.

The Formosat-2 image has also been enlarged for Beichuan, again in before and after format. This is available here. This the before image:

This is the after image annotated to show the big landslide:

Note that the river appears to be blocked in this image too. There is no evidence of flow. Note also that the location of the very damaging landslide does not appear exceptional in the "before" image - this is a forested slope that looks the same as the surrounding slopes.

Finally, there are now ALOS images (both optical and radar) available. Radar adds little as the data are very difficult to interpret without processing. The optical image is better, and indeed has been annotated to indicate the location of landslides. To my eye there are many landslides that have not been annotated. Unfortunately the resolution is too low to be really helpful in this form. This is the image (click for a bigger view - warning this is a big file):

Updated: The Beichuan landslides in the Sichuan earthquake

Some information is now becoming available about the impact of landslides in Beichuan. I have blogged before about this. However, a report in the Chinese Economic Observer online is now beginning to highlight just how bad the problem actually has been. This report states the following:

In fact, landslides triggered by the May 12 earthquake had exacerbated the destruction in Beichuan. Take Maoba Middle School for instance, all traces of its existence – save a basketball hoop in the far end of a field – had "vanished" under fallen boulders from the hills. Of the 400 or more students and teachers there, merely one to two percent survived. What's more disturbing was that the landslide had blocked the flows of the White River, creating an artificial lake in its upstream, near the Kuzhuba hydrolic dam. If the water pressure built up and threatened to burst the dam, the cost of life and property would be dreadful. The risks involved had added urgency and hazards to the rescue work that was racing against time.

The Taiwanese Formosat-2 satellite has collected an image that shows this landslide. This is shown below, annotated to show the landslide:

It appears from this image that the school is not the only structure to have been hit by this landslide. This is also apparent from these newswire photographs, which show the site:

Caption: Rescuers looks at a Chinese flag and a basketball loop among the rubble of a school after it was flattened by falling rocks following Monday's 7.8 magnitude earthquake in Beichuan county, Sichuan province, China, Friday, May 16, 2008.

Caption: A Chinese flag and a basketball loop are seen among the rubble of a school after it was flattened by falling rocks following Monday's 7.8 magnitude earthquake in Beichuan county, Sichuan province, China, Friday, May 16, 2008.

Updated 18th May: Reported landslides from the 2008 Sichuan Earthquake

I am starting a second thread here to document landslides reported in the Sichuan earthquake. Background information about landslides and the earthquake is provided in the post below. I will update this list as new information becomes available. I would really welcome any information that can be provided - please email me ( d.n.petley@durham.ac.uk ) or post a comment.

General observation: as feared, landslides have taken a terrible toll in this earthquake. Reports from almost every town in the mountains suggest that landslides and rockfalls have killed large numbers of people. For example, Xinhua report:

The road from Dujiangyan, a city northwest of the provincial capital Chengdu, to Wenchuan, the epicenter, was blocked by rocks and mud slides, holding up rescue, medical and other disaster relief teams.

These landslides continue to cause serious disruption to the relief efforts. Again, Xinhua have said:

The official said the vice governors treked into Yingxiu after many hardships and several close brushes with death. Rocks were still rolling down from the mountains on Wednesday. The highway linking Yingxiu and Dujiangyan City was totally paralyzed and a bridge on the highway had collapsed, hampering the arrival of rescuers.

A few photographs are starting to emerge of the landslide damage. For example, Xinhua again have this image, which shows extensive fresh landslides:

Update: 18th May
Location: Donghekou, Ciban and Kangle villages
Report: International Herald Tribune
A mountain sheared off by China's massive earthquake swallowed the village whole, entombing an unknown number of people inside a huge mound of brown earth. The road to the village ends in a tangled twist of metal and tar. The landscape, eerie and still, shows few signs of human life — a soiled green floral scarf, a rubber pipe, a log. Wen Xiaoying, 32, held up a hand as she ticked off the family members buried in the muck before her — her father, her mother, her sister and her brother-in-law. The landslide blocked the valley's Qingzhu river and a lake was swelling behind the wall of debris, posing the threat that it could break its banks and send torrents cascading into villages downstream. Locals said two other villages further upstream from Donghekou — Ciban and Kangle — suffered the same fate as Donghekou. The three villages were home to about 300 families, locals said. "When I saw them the last time, we had a good time together," said Wen, a glimmer of a smile showing through as she remembered happier days with her family. "I didn't expect it would be the last time I saw them."

Update: 17th May
Location: Bai He river upstream from Beichuan
Report: The Independent
Mountains separate Hanwang from Wenchuan county, the epicentre of the quake, which is still cut off after Monday's 7.9 magnitude quake and where many thousands are feared dead. Soldiers who parachuted in to the county said four villages had been overwhelmed by landslides after the quake.

Update: 16th May
Location: Bai He river upstream from Beichuan
Report: Monster and Critics

A lake had formed on the Bai He river above Beichuan town after a landslide caused by the earthquake blocked the river, an official from the Sichuan Seismological Bureau told Deutsche Presse-Agentur dpa by telephone. Because of the high risk of flooding, troops evacuated everyone to higher ground before returning to continue their rescue work in Beichuan, which was home to about 30,000 people, state media said. The Sichuan official declined to respond when asked how the government planned to tackle the blockage on the Bai He.

Update: 14th May @ 07:00
Location: Huixian county, Longnan, Gansu
Report: Reuters

The flow of the Jialing River has been effectively blocked in Huixian county, in south-eastern Gansu's Longnan region, by landslides triggered by the quake, the Xinhua news agency said. Rubble created a 6-meter tall, 30-meter wide and 100-meter long dam, holding back 600,000 cubic meters of water. Commentary: valley blocking landslides presenta very serious threat in earthquake affected areas. Unless mitigated, this dam is liable to coollapse, which would create a devastating flood.

Update: 13th May @16:00
Location: Beichuan, Sichuan - see more detailed update here
Report: People's Daily Online and Xinhua
The county seat of Beichuan, about 160 km northeast of the Wenchuan, was almost leveled. As of early Tuesday, up to 5,000 people were said to be dead there, having been killed not in collapsed buildings but by landslides. The county seat was surrounded by hills 500 to 1,000 meters high. "When the quake struck, rocks rolled down the mountains and buried houses. People had no time to run out, and there was nowhere to run, as roads were blocked," said a survivor surnamed Zhang.


This is a Google Earth image of Beichuan (click on it for a better view). The site is indeed surrounded by steep mountains. Note the deep "bite" out of the mountain above the town - could this be an old landslide source zone? The town has not been completely buried by landslides, as this Xinhua image shows:

But it is likely that at least some of the damage has been the result of landslides and rockfalls.

This image appears to show that landslides have been a serious cause of loss of life in Beichuan:


Original list:
Location: Maoxian County, Aba Prefecture
Report: AFP
At least 37 tourists have been killed and about 15 British tourists were reported missing following the earthquake in China’s Sichuan province, emergency management office said Tuesday. “A tourist coach was buried by a landslide in Maoxian County, Aba Prefecture, leaving 37 people dead,” a Sichuan provincial emergency management spokesman said.

Location: Beichuan County
Report: Xinhua
Beichuan County was by far the worst-hit area in Monday's quake. Up to 7,500 people were said to have died in Beichuan, and it is believed that the final death toll will be higher. "When the quake hit, the buildings rocked and the mountains collapsed," said a survivor surnamed Zhang. "Many buildings at the foot of the mountains were buried and the people inside had no chance to escape." He said he feared the quake could have killed at least half of the 18,000 people in the county seat. "I saw many people running out of buildings, only to be buried in landslides," said Lei Xiaoying, another survivor. "The landslides never stopped because of the continuous aftershocks."

Location: Yingxiu Town, Wenchuan County
Report: Xinhua
A village was immediately engulfed by landslide and water level in a reservoir rose rapidly, recalled an earthquake survivor who is still haunted by terrible memories on Tuesday. The man named Yang Yang told He Biao, deputy secretary-general of Aba prefectural government that he was on a bus in Yingxiu Town, Wenchuan County of Sichuan Province, the epicenter of the earthquake that claimed at least 9,000 lives. "I saw a village on the mountainside disappear in a landslide triggered by the earthquake. Many vehicles on the road were swept away or hit by huge rocks," Yang was quoted by He Biao as saying.The water level in Zipingpu Reservoir also rose quickly, Yang said.

Location: The road from Dujiangyan to Wenchuan, Sichuan
Report: Xinhua
The road from Dujiangyan, a city northwest of the provincial capital Chengdu, to Wenchuan, the epicenter, was blocked by rocks and mud slides, holding up rescue, medical and other disaster relief teams.

Location: Jushui town, northern Sichuan
Report: Xinhua
"We were passing by the Jushui town, and we saw a huge landslide," a man from Mianzhu City, about 60 kilometers to quake center Wenchuan, told Xinhua over the phone. "Rocks buried many houses down at the foot of the hill, and some of the vehicles on the road were buried too. I saw the rear of a car and the wheels of another. Several people were crying for help and some were bleeding," he said.

Location: 312 national highway near the Wenchuan county, Sichuan
Report: Xinhua
A driver from the Sichuan provincial seismological bureau had been on the 312 national highway near the Wenchuan county when the tremor occurred. "I heard someone calling 'earthquake' and felt my car swaying. Rocks rolled off the hills and dust darkened the sky," he recalled.

Location: Dujiangyan city
Report: Xinhua
Xinhua reporters had attempted to go to Wenchuan, but were stopped at Dujiangyan city 100 kilometers away, where roads were blocked by rocks.

Location: Various railway tracks near Chengdu (15 reported landslides)
Report: Xinhua
Monday's strong earthquake in southwest China's Sichuan Province have caused multiple landslides and collapses along railway lines near the provincial capital Chengdu, leaving 180 trains stranded on the rails. Thirty-one passenger and 149 cargo trains were stranded on the Baoji-Chengdu line, the Chengdu-Kunming line, the Chengdu-Chongqing line and their branch lines linking Chengdu with the rest of the country. At least 15 cases of landslides and collapses had so far been reported along rail tracks.

Updated 16th May (twice): Sichuan Earthquake landslide images

I thought a thread showing some news images of landslides triggered by the Sichuan earthquake would be useful. The first image shows vividly the likely impact of landslides in this area.

AP photo entitled "Buildings are destroyed by landslides following Monday's powerful magnitude 7.9 earthquake in Beichuan in Mianyang city in southwest China's Sichuan Province Tuesday, May 13, 2008. A signboard atop the building at left reads: Beichuan Hotel"

Xinhua image entitled: An aerial photo taken on May 14 shows the road from Dujiangyan city to Wenchuan County in southwest China's Sichuan Province is destroyed by landslide caused by Monday's earthquake. The serious devastation of the road affected the transportation of rescue teams and relief materials to the disaster areas


Reuters image entitled: "A damaged highway is seen after an earthquake in Beichuan, Sichuan province May 13, 2008. "

Xinhua image entitled "An aerial view shows the earthquake-hit town of Yingxiu in Wenchuan County, Sichuan province May 14, 2008"

Reuters image entitled "Vehicles are stranded on an earthquake-affected highway linking Dujiangyan to Wenchuan, May 15, 2008. China poured more troops into the earthquake-ravaged province of Sichuan on Wednesday to speed up the search for survivors as time ran out for thousands of people buried under rubble and mud."

Reuters image entitled "Vehicles are stranded on an earthquake-affected highway linking Dujiangyan to Wenchuan May 14, 2008."

Reuters image entitled "Soldiers use explosives to clear a road leading to an earthquake-hit village in Dujiangyan, Sichuan province, May 14, 2008."

Xinhua image entitled "a volunteer helps a woman walking out of the earthquake-stricken area in Mianzhu city of southwest China's Sichuan Province, Wednesday, May 14, 2008."

Xinhua image entitled "A soldier from the People's Liberation Army makes his way to the quake-stricken Yingxiu town of Wenchuan county, Sichuan province, May 14, 2008"

Reuters image entitled: "A general view shows the earthquake-hit Beichuan county, about 160 km (99 miles) northeast of the epicenter of Wenchuan county, Sichuan province, May 14, 2008."

Reuters / Stringer image entitled "A local resident walks among the debris of collapsed buildings at the earthquake-hit Beichuan county, about 160 km (99 miles) northeast of the epicentre of Wenchuan county, Sichuan province, May 14, 2008."

Reuters image entitled "A view of the earthquake-affected Beichuan county, Sichuan province, May 13, 2008."

The Dorset landslide revisited

It is now sensible to revisit the 7th May Dorset landslide, upon which I blogged here. Now, eight days on, it is clear that there was a slight media over-reaction to this event, probably spurred by reported comments that this was the largest failure for a century. It wasn't.

The image below from the BBC, clearly shows what actually happened. A section of cliff has collapse from the Blue Lias at the front of the landslide complex. The failure is wide but does not propagate very far inland. This is much smaller than other recent movements on this landslide complex, albeit visually dramatic from the beach. It is true that if there had been people on the beach at the time the consequences could have been serious. However, there weren't, meaning that this is not a really significant event.


John Lock has very kindly provided two images from the Lyme Regis side, which I reproduce below. The first shows the site of the landslide before the failure, taken from the Lyme Regis side, the second shows the same site afterwards.

Of course, the interesting factors here are:
1. The way in which the media provide misleading impressions of what actually happened; and
2. The potential implications for stability upslope given the loss of the toe of this part of the complex. I am sure that the local authority will now be pretty active in assessing the latter.

Sichuan landslide problems - the seasonal issue

To illustrate the problems with landslides that the Chinese authorities now face, I have plotted the occurrence of rainfall induced landslides in Sichuan for 2005, 2006 and 2007 by month, using data from the Durham University landslide database. We know that the occurrence of landslides increases dramatically after large earthquakes, especially in the rainy season. Figure 1 shows that landslides in Sichuan occur in the period May to September .

Figure 1: Monthly occurrence of fatalities from landslides in Sichuan, as recorded in the Durham University Landslide Database. (Click on the graph for a better view)

The picture is clear - the occurrence of rainfall induced landslides begins in May and lasts through to October, with the peak occurring in July. In fact, with the exception of a single event in March, the earliest fatal landslide in this period occurred on 20th May.

The implications for the earthquake affected areas are very clear - assuming that the rains do occur as per usual (and there is no reason to believe that they won't), landslides are going to be a very serious problem in the coming months.