Overview photo of the Bandung landslide

The Jakarta Post has an overview image of the Bandung landslide:

Massive landslide in West Java, Indonesia

A large landslide occurred yesterday in the Dewata tea plantation area in Pasir Jambu, Southern Bandung in West Java, Indonesia, burying the accommodation for temporary plantation workers. It is estimated that 70 people were buried by the slide. This image, from AP, appears to show the head of the landslide, which looks to be a large but comparatively shallow flow type failure in regolith:


The toe of the slide, including some of the impacted buildings, is shown in this AP image:


News reports suggest that to date 7 bodies have been recovered from the debris, with rescue operations continuing amongst heavy rainfall, which must place the workers at considerable personal risk.

Java consistently appears in the landslide database with very high fatal landslide occurrence. Tea plantations are also areas of high landslide hazard.

A surprising spell of landslides

In most years in which I have been collecting landslide fatality statistics (since 2002) November has been a month with quite low landslide occurrence. Not this year though - in fact the last few days have been more like the summer monsoon season, with fatal landslides occurring in a wide range of places. Examples include:

• El Salvador on 6th November, in which the volcanic lahars triggered by Hurricane Ida appear to have killed over 100 people, with a few (very speculative) reports of rather more;
• South Sulawesi in Indonesia, when 13 people were killed in a slide Palopo;
• Tamil Nadu on 9th and 10th November, when a number of landslides killed at least 30 people;
• Casamicciola on Ischia in Italy on 9th November, when a 15 year old girl was killed by a slide that carried her out to sea in a bus;
• Bukittinggi in West Sumatra on 10th November, when two people were killed;
• Wassa-Akropong in Ghana on 10th November, when up to 30 people were killed in a landslide in an illegal mine;
• Goha village in Tanzania on 10th November, when 20 people were killed in a landslide.

In addition there have been reports of non-fatal landslides in the USA, Serbia, Vietnam, etc. I cannot tell at the moment whether this is just coincidence or something more significant, perhaps due to the El Nino conditions. With Cyclone Phyan currently bringing heavy rainfall to central western India, an area that is landslide-prone, there could be further events in the next few days.

More images of the earthquake-triggered landslides in Sumatra

I thought it would be useful to provide a compilation of images of the landslides triggered by the Sumatra earthquake. ReliefWeb is reporting that over 1000 landslides were triggered: "Landslides have hindered relief efforts in some areas. The West Sumatra Satkorlak reported at least 1,000 landslide spots in Gunung Tigo highlands, located between Padang Pariaman and Agam districts. Six helicopters carrying food and medical supplies were dispatched to the highlands as landslides blocked roads." Interestingly, the landslides appear to be highly mobile, (comparatively but not very) shallow flows in deeply weathered soils. They have run out over quite large distances and in some of the images there appears to be large amounts of water present.

From here, "A highway is severely damaged by a landslide after an earthquake occured near the Padang Alai village area in Pariaman, West Sumatra province"
From Reuters, "A motorbike is covered in mud after it was unearthed in the earthquake ravaged village of Tandikat, Indonesia's West Sumatra province October 6, 2009".


From Reuters, "An aerial view of a village hit by a landslide which occurred when an earthquake hit the area in Pariaman district, West Sumatra province October 6, 2009."


From Reuters, "An aerial view of villages hit by a landslide which occurred when an earthquake hit the area in Pariaman district, West Sumatra province October 6, 2009."


From Reuters, "An aerial view of villages hit by a landslide which occurred when an earthquake hit the area in Pariaman district, West Sumatra province October 6, 2009."

From Reuters, "Indonesian soldiers and police search victims buried after a quake-triggered landslide in Jumanak in Padang Pariaman district, Indonesia, Monday, Oct. 5, 2009."

From Reuters, "An aerial view of the damage after a landslide caused by a powerful earthquake in Limo Koto Timur village in Padang , Indonesia's West Sumatra province, October 4, 2009."

The elephant and the landslide

In one of the strangest stories of the year, Tempo Interaktif in Indonesia reports the death of an elephant, and three people, in a landslide in Sumatra:

"Heavy rains in Lampung Province have triggered landslide which killed three people in Tanggamus Regency and cut the Sumatra inter-provincial road in the western coast of the island on Sunday. A hillside was heavily eroded by the rain and mudslide blocked the main inter-provincial road in Way Kerap Village in Semaka Tanggamus Subdistrict. One wild elephant was also killed by the mudslide in Tanggamus."

It is of course irrational to feel more sad about the death of the elephant than that of the people, but this is a commonly-experienced feeling in these situations. I am not sure why.

Emerging news of landslides triggered by the Sumatra earthquake

It is interesting to note that in all three of the large earthquakes upon which I have worked (1999 Taiwan, 2005 Pakistan, 2008 China), the media has tended to initially focus their coverage upon urban areas, whilst the real story has actually been in the rural hinterland. The reasons for this are complex of course, and include the power of the imagery of people buried / being rescued from buildings. However, the main reason is of course that in upland rural areas landslides kill large numbers of people whilst also destroying communications links and power infrastructure. Thus, the disaster in these areas goes unreported for some time; even the government is often unaware of this situation. As I tell my students, in this case no news is definitely bad news - if no information is coming out about these upland rural areas then the situation is probably dire.

And so it has proven once again in the Sumatra earthquakes. It appears that yesterday communications infrastructure reached the point in which aid, and of course journalists, could start to get into the upland areas, whereupon it became clear that there has been a substantial disaster during this earthquake. AP have distributed this aerial overview shot, showing a series of large flow type failures in Padang Pariaman district:

There are various reports about the impact of this landslide, which appears to have destroyed four hamlets: Pulau Aie, Lubuk Laweh, Cumanak and Gunung Tiga. Some reports suggest quite high fatality totals (>650 people). In this case local knowledge may be the most reliable, so I have taken a look at the Jakarta Post report, which says:

"Three hamlets have gone and 400 people are feared dead as the earthquake that shook West Sumatra on Wednesday produced a landslide that pushed the hamlets of Kapalo Koto, Cumanak and Lubuk Laweh into a river. An area of at least five square kilometers was buried by a huge landslide falling down from the nearby hills. A mosque which had stood 30 meters high disappeared with the hamlets. "

The higher death tolls being quoted elsewhere from this slide may be because the media are conflating estimates of the loss of life from all landslides with the losses from this single event. This is a Reuters quote from a Health Ministry Official:

"In the villages in Pariaman, we estimate about 600 people died," said Rustam Pakaya, head of the Health Ministry's crisis centre. Pariaman, closer to the epicentre, is one of the worst-affected.
In one of the villages, there's a 20-metre-high minaret, it was completely buried, there's nothing left, so I presume the whole village is buried by a 30-metre deep landslide."

It is easy to read that quote as suggesting that 600 died in a single slide, but actually he is suggesting that this might be the loss "in the villages of Pariaman".

The high loss of life in that particular landslide appears to be related to the fact that one of the villages was hosting a wedding party at the time of the landslide. There are a couple of other AP images of what is reported to be this landslide (although it could also be a different failure):


Unfortunately this landslide is certainly not the only one to have caused fatalities. The image below appears to show a different landslide (and note that in the background another failure can just be seen). Here it appears that a building has been incorporated into the slide:

Meanwhile the BBC have a report here from another village affected by landslides, including a large failure in which the reporter suggests that ten people died.

Whilst the main concern at the moment must be the emergency response, a serious medium term worry will be that the rainy season for this area starts in November. Landslides will pose a very substantive hazard during that period.

Typhoon Parma update, plus landslides in Indonesia, India, Sicily, Samoa, Cambodia and Vietnam

I am struggling to keep up with the natural disasters at the moment. The main point of this post is to highlight the continued threat of Typhoon Parma to the northern Philippines. The current track forecast has it making landfall in the next day or so in the northern part of Luzon. The forecasts are still that it will stall as it makes its way across that area - this is typically the scenario that leads to very heavy rainfall and hence many landslides. Note also that at the moment it is not clear where it will go once it clears the Philippines, but the South China Sea is warm, which could lead to a re-intensification:

Meanwhile the last week has been grim for landslides:

1. The Samoa earthquake and tsunami has received some publicity, but has been overshadowed by events elsewhere. The intensity of the shaking may well have triggered some landslides, and of course there is the possibility that a submarine slide contributed to the tsunami;
2. The Indonesian Earthquakes: there are lots of reports of landslides triggered by the earthquakes. These slides appear to have cost lives directly and also to be hampering the rescue operations due to blocked roads.

3. Typhoon Ketsana: Cambodia and Vietnam were both hit very hard by typhoon Ketsana. Reported death tolls are 99 people in Vietnam and 14 people in Cambodia, adding to the reported 293 fatalities in the Philippines. In each case landslides appear to have been a major factor.

4. Rain in India: 140 people are reported to have been killed in heavy rainfall in the states of Karnataka, Andhra Pradesh and Maharashtra. At least some of these are the result of landslides - for example, a single landslide killed eight people in Maharashtra yesterday.

5. Mudslides in Sicily: heavy rainfall in Sicily last night triggered extensive mudslides around Messina killed at least 14 people. Image below from here (not my normal daily read I should quickly add):

I cannot remember a time with so many events occurring simultaneously. Certainly an interesting time as the old curse says.

The Cikangkareng village landslide, Indonesia

As I reported a couple of days ago, the Mw=7.0 earthquake in Indonesia on Wednesday triggered a substantive landslide in the village of Cikangkareng in West Java. This landslide buried ten houses, a mosque and an amusement (video game) arcade with the loss of about 57 lives. AP have today released images of the landslide that are quite interesting. In particular this one:

Why is this interesting? Well, first lets note that we should ignore the red colour on the face of the scarp - this is a mantle of tropical soil that have come down from the crown of the slide (you can see the red soil at the very top of the landslide - this is of course typical of a tropical area). More important is the structure behind the mantle of soil debris. Here it is clear that the rocks are horizontally-bedded (or at least nearly so). Such a large failure in horizontally-bedded rocks is certainly not unprecedented, but is slightly surprising. The debris is very coarse-grained and has travelled quite a long way, which is also interesting.

Often, failures like this are associated with some process that has caused undercutting of the toe - for example wave erosion. Clearly there are no waves here - I wonder if there had been any activity to quarry stone from the slope, perhaps as a building material?

I am reminded of the Manshiet Nasser landslide in Cairo a year ago:

In that case the key cause was probably quarrying at the foot of the slope.

Updated: A large landslide triggered by the latest Indonesian earthquake

A large (Mw = 7.0) earthquake struck offshore Java in Indonesia today at 07:55 UTC (2:55 am local time). USGS has a location map (below) and earthquake parameters, a shake map, etc here.

AP is reporting that a large landslide was triggered in Rawa Hideung village, Cianjur district in Java:

"Antara reported that 12 families, or about 30 people, were trapped in houses buried by the landslide in Rawa Hideung village, Cianjur district. Six bodies had been recovered and the fate of many others was unknown, a resident, Agus Sobandi, was quoted as saying."

Java appears as one of the most serious hotspots on the global landslide dataset that I collate, so the occurrence of slides from this earthquake is not surprising. There may well have been many more landslides.

Update: The Indonesian National Disaster Agency BNPB has a report on its web page about the earthquake here. This is in Indonesian, but Google can translate this to English. The key element from a landslide perspective is (unedited translation): Cianjur: "Interim report, there were 10 people died in landslides buried, with details of the 9th district residents and 1 Cibinong Sukanegara citizens. A total of 11 houses in the district Jembrong severely damaged and landslides buried Cikado district offices to the ground."

Landslide in Lombok, Indonesia

The Jakarta Globe is today reporting a quite large landslide at Buwun Mas village in West Nusa Tenggara Province. This slide is reported to have killed at least four people, with a further 11 potential victims believed to be buried in the debris. The report is quite interesting as it says that:

"The area, [Rustam Pakaya, the head of the Ministry of Health’s Crisis Center] said, is used for illegal gold mining. “We are still searching for the missing people,” Rustam said. “We don’t have any information yet on who these victims are. We don’t know if they are miners or not.”

It should be said that other, unfortunately non-local, reports are rather more certain about the mining issue:

"A landslide at a gold mine killed four workers and left 11 missing on the Indonesian island of Lombok, a Health Ministry official said Sunday."

Fortunately, this is an area with excellent Google Earth imagery, so a quick look at the site of the landslide shows the following (click on the image for a better view in a new window):

The area around the village appears to be quote densely forested, but note that the Google Earth data covers the junction between two epochs (periods) of imagery, which you can see from the colour change across the image above. I have shown this below:


Note how to the west of the line (north is approximately at the top of the image) the forest cover is quite intact, but to east it is mainly denuded. The junction is along the line that I have marked above. This presumably means that the imagery to the west is older and was taken when the forest was mostly intact, whilst to the east the images are more recent. In the meantime there has been extensive deforestation. Unfortunately, the consequences are all to clear to see - to the east of the line the ground is visibly eroded. Just a couple of kilometres from the village there is an area of extensive recent shallow landslides:

A perspective view shows that these are breaking out all over the deforested landscape:

Given that this is an area of illegal mining and extensive deforestation, the occurrence of destructive landslides should not be a surprise. The level of vulnerability here is indicated by the fact that the Tropical Rainfall Measuring Mission have not detected unusually high levels of rainfall in this area over the last few days.

The combination of deforestation and mining in tropical environments is really bad news from a landslide perspective.