Thursday, May 14, 2009
Another Chinese tailings dam failure
The Chinese media are reporting another tailings dam failure, this time in Hunan province. Fortunately, the effects appear to be far less devastating than this event last year. The reports suggest that a manganese ore tailings dam failed in Huayuan County, Xiangxi Autonomous Prefecture in Hunan Province early on Thursday morning, releasing a flowslide that hit a house, killing three people and injuring four more.
Tuesday, May 12, 2009
So what have we learnt from the Wenchuan (Sichuan) Earthquake?
Driving home from work last night, and bored with listening to endless discussions on the radio about the ways in which politicians use the system to personal gain, I started pondering what we have learnt from the Wenchuan Earthquake a year ago. The media yesterday understandably focused on collapsed schools. We have known for years that critical buildings in earthquake zones need seismic reinforcement, so this is hardly new. These are the key things that I think we have learnt (you may have more, so I welcome comments):
1. Our current rapidly-generated maps of the distribution of earthquake shaking are not good enough.
In China it is clear that the area of maximum damage occurred on the hanging wall (NW side) of the fault, with the peak being very close to the surface trace of the fault. Many of the early maps suggested that maxim,um damage would be in a zone centred around the epicentre. Unfortunately this meant that at least a part of the rescue effort was misdirected. The need for strong motion instruments across an earthquake-vulnerable area that can telemeter (send) the data back to a central station is clear. This is what happened in 1999 in Taiwan. Additionally, further work is clearly needed to allow the rapid generation of reliable shake maps.
2. Communications are critical.
In China there was a major problem with communications from the most seriously-affected areas. With no telephones or power, and with all of the roads blocked by literally hundreds of landslides, getting information out about the impact proved impossible. This was compounded by a lack of understanding from the Chinese government about the likely level of damage. On the afternoon of the earthquake the Chinese Premier Wen Jiabao ordered that the roads to the epicentral areas should be reopened by before 12 p.m the day after the earthquake. Clearly there was no comprehension of what things were like in the mountain regions - and Wen is a geologist! This is not a criticism of Wen or the Chinese government - how could they possibly have known that things were so bad - but rather of the landslide community - of which I am a part - for failing to make governments aware of the implications of landslides in mountainous earthquake zones (see below).
3. Landslides play a major role in mountain area earthquakes.
Until now the earthquake community has failed to appreciate the major role that landslides cause in earthquakes in upland areas. About a third of the fatalities occurred as a result of landslides; landslides also to a large degree prevented the delivery of aid; landslides blocked valleys causing a major secondary hazard (see below); and landslides now generate much of the long term hazard in the affected areas.
4. Valley blocking landslides can be mitigated.
This is the first large earthquake in modern times that has created very large numbers of valley-blocking landslides. The Chinese demonstrated that these hazards can be successfully mitigated, but that it requires the availability of the right tools, experience and resources. The Chinese achievement is extraordinary - I wonder if the rest of the world could cope so well?
5. Satellite tools are still not up to the job.
For years we have been hearing that satellites provide the capability to get an almost instant view of what has happened in disaster zones. There are more satellites available than ever, but imagery proved to be of almost no use at all in the recovery phase. The problems remain that the instruments with the highest resolutions cannot see through clouds and it is very difficult to get the data into a format that is usable on the ground.
1. Our current rapidly-generated maps of the distribution of earthquake shaking are not good enough.
In China it is clear that the area of maximum damage occurred on the hanging wall (NW side) of the fault, with the peak being very close to the surface trace of the fault. Many of the early maps suggested that maxim,um damage would be in a zone centred around the epicentre. Unfortunately this meant that at least a part of the rescue effort was misdirected. The need for strong motion instruments across an earthquake-vulnerable area that can telemeter (send) the data back to a central station is clear. This is what happened in 1999 in Taiwan. Additionally, further work is clearly needed to allow the rapid generation of reliable shake maps.
2. Communications are critical.
In China there was a major problem with communications from the most seriously-affected areas. With no telephones or power, and with all of the roads blocked by literally hundreds of landslides, getting information out about the impact proved impossible. This was compounded by a lack of understanding from the Chinese government about the likely level of damage. On the afternoon of the earthquake the Chinese Premier Wen Jiabao ordered that the roads to the epicentral areas should be reopened by before 12 p.m the day after the earthquake. Clearly there was no comprehension of what things were like in the mountain regions - and Wen is a geologist! This is not a criticism of Wen or the Chinese government - how could they possibly have known that things were so bad - but rather of the landslide community - of which I am a part - for failing to make governments aware of the implications of landslides in mountainous earthquake zones (see below).
3. Landslides play a major role in mountain area earthquakes.
Until now the earthquake community has failed to appreciate the major role that landslides cause in earthquakes in upland areas. About a third of the fatalities occurred as a result of landslides; landslides also to a large degree prevented the delivery of aid; landslides blocked valleys causing a major secondary hazard (see below); and landslides now generate much of the long term hazard in the affected areas.
4. Valley blocking landslides can be mitigated.
This is the first large earthquake in modern times that has created very large numbers of valley-blocking landslides. The Chinese demonstrated that these hazards can be successfully mitigated, but that it requires the availability of the right tools, experience and resources. The Chinese achievement is extraordinary - I wonder if the rest of the world could cope so well?
5. Satellite tools are still not up to the job.
For years we have been hearing that satellites provide the capability to get an almost instant view of what has happened in disaster zones. There are more satellites available than ever, but imagery proved to be of almost no use at all in the recovery phase. The problems remain that the instruments with the highest resolutions cannot see through clouds and it is very difficult to get the data into a format that is usable on the ground.
Monday, May 11, 2009
The Wenchuan Earthquake - one year on
No words can do justice to the first anniversary of the Wenchuan (Sichuan) earthquake, so I won't even try. Instead I post these pictures as a silent memorial to the victims.
Tuesday, May 5, 2009
Early May is the start of the landslide season
Whilst the transition towards the Northern Hemisphere summer is rather pleasant for many of us, the start of May also marks the start of the landslide season in the Northern Hemisphere. Of course the main problems kick in when the SW monsoon really gets going in Asia and the tropical cyclone season properly begins in the N. Pacific and N. Atlantic basins, but already there are clear signs that the land is starting to move. Overnight, a number of Pakistani news agencies have reported a large landslide in the Neelam Valley:
"At least 28 people were trampled to death due to landslide in Neelam Valley on Tuesday, Geo news reported. According to sources 28 people have been trapped under the landslide in Jora area here in Neelam Valley, part of Azad Jammu and Kashmir (AJK). The rescue activities have been kicked off after the tragic incident and the trapped dead bodies of the unfortunates are being dug out, sources added."
Of course the Neelam Valley was pretty badly affected by the 2005 earthquake (the image below shows a part of the valley in 2006), so ongoing landslide problems here are not a surprise.
Meanwhile, the Philippines has already been battered by one typhoon (named Kajira in the Pacific-wide system, or Dante in the Philippines), which triggered a landslide in Sorsogan that killed 23 people. Unfortunately, there is another one (Chan-Hom) en route for northern Philippines at the moment (Tropical Storm Risk):
The good news is that Tropical Storm Risk (see long term forecast here) are forecasting a below average season for typhoons (activity is anticipated to be 20% below the long term mean). The long term forecast for the monsoon in India is essentially average (forecast rainfall = 96% +/-5% of long term mean.
"At least 28 people were trampled to death due to landslide in Neelam Valley on Tuesday, Geo news reported. According to sources 28 people have been trapped under the landslide in Jora area here in Neelam Valley, part of Azad Jammu and Kashmir (AJK). The rescue activities have been kicked off after the tragic incident and the trapped dead bodies of the unfortunates are being dug out, sources added."
Of course the Neelam Valley was pretty badly affected by the 2005 earthquake (the image below shows a part of the valley in 2006), so ongoing landslide problems here are not a surprise.
Meanwhile, the Philippines has already been battered by one typhoon (named Kajira in the Pacific-wide system, or Dante in the Philippines), which triggered a landslide in Sorsogan that killed 23 people. Unfortunately, there is another one (Chan-Hom) en route for northern Philippines at the moment (Tropical Storm Risk):
The good news is that Tropical Storm Risk (see long term forecast here) are forecasting a below average season for typhoons (activity is anticipated to be 20% below the long term mean). The long term forecast for the monsoon in India is essentially average (forecast rainfall = 96% +/-5% of long term mean.
Nailing Jell-o to a wall...
This is a guest post from Bill Rabenaldt from California about a novel soil nail mitifation technique.
Can you nail jell-o to a wall? Not easily. Can you nail a landslide area, levee or bluff before it fails? You bet!
The valley floors around Aspen, Telluride and other resort areas in the Rockies are all but built out. Where do business and families go? The surrounding hills and mountain sides are all that is available. I’ve seen pictures of several of these homes and they are spectacular. Generally, the home theaters and pools are built into the mountain side due to local height restrictions.
How are they doing it?
For the past 10 years, I have been a member of the Pismo Beach City Council. Our community is on the Central Coast of California half way between San Francisco and Los Angeles, just north of Santa Barbara. During that time, I’ve learned a lot. As an example, our bluff has eroded faster than expected in some areas and we are in immediate danger of losing our highway, force mains and our underground utilities. Pebble Beach was another coastal community that was in danger of having their main arterial fall into the ocean. Trying to figure out how we can overcome these natural and man-made disasters has been my personal and political motivation for many years.
There are also the devastating fires we’ve had around the world. Rains are causing landslides of varying proportion. Our once stable private and public property is now vulnerable to the forces of nature. Our levee system is old and decaying.
There is a company I’ve been following for about 7 years. I first met them at the League of California Cities meeting in Sacramento. Soil Nail Launcher had a booth at the event and I was interested in how an 8 foot nail could be driven into an embankment. Over the years, I understand they have driven many nails and have protected a whole lot of property. Not only that, they have done it for less than half the cost of traditional methods.
Here is a short story you will enjoy:
In WW2, Great Britain developed a gas canister launcher to stop the enemy’s progress. A canister could be launched as far as 3 miles away. Several years ago, a company bought this equipment and all the patents and converted it to a “soil nail launcher”. 2,500 psi is built up in a chamber and launches a nail at 220 mph into the unstable soil. These nails are typically between 12 and 20 feet long with a Super Launcher that penetrates up to 80 feet. The area is then left to nature or a shotcrete surface can be applied.
If you would like to see what intrigued me the most, go to their website: www.landslidesolutions.com to see what they have accomplished. Their services are averaging half of the cost of traditional “fixes”, they were approved by the California Coastal Commission, they have recently received a GSA (General Services Administration) contract number from the Federal Government for emergency services. They can solve geotechnical, construction and public safety problems.
A recent report by the geological society on the new faults found along the infamous San Andreas Fault causes serious doubt as to the earlier government findings of “acceptable standards” for construction, land use issues, and a host of other many other conclusions that must be reviewed. Many may need to be reconsidered and/or revised with this new information. Reinforcement may be the only logical solution.
Can you nail jell-o to a wall? Not easily. Can you nail a landslide area, levee or bluff before it fails? You bet!
The valley floors around Aspen, Telluride and other resort areas in the Rockies are all but built out. Where do business and families go? The surrounding hills and mountain sides are all that is available. I’ve seen pictures of several of these homes and they are spectacular. Generally, the home theaters and pools are built into the mountain side due to local height restrictions.
How are they doing it?
For the past 10 years, I have been a member of the Pismo Beach City Council. Our community is on the Central Coast of California half way between San Francisco and Los Angeles, just north of Santa Barbara. During that time, I’ve learned a lot. As an example, our bluff has eroded faster than expected in some areas and we are in immediate danger of losing our highway, force mains and our underground utilities. Pebble Beach was another coastal community that was in danger of having their main arterial fall into the ocean. Trying to figure out how we can overcome these natural and man-made disasters has been my personal and political motivation for many years.
There are also the devastating fires we’ve had around the world. Rains are causing landslides of varying proportion. Our once stable private and public property is now vulnerable to the forces of nature. Our levee system is old and decaying.
There is a company I’ve been following for about 7 years. I first met them at the League of California Cities meeting in Sacramento. Soil Nail Launcher had a booth at the event and I was interested in how an 8 foot nail could be driven into an embankment. Over the years, I understand they have driven many nails and have protected a whole lot of property. Not only that, they have done it for less than half the cost of traditional methods.
Here is a short story you will enjoy:
In WW2, Great Britain developed a gas canister launcher to stop the enemy’s progress. A canister could be launched as far as 3 miles away. Several years ago, a company bought this equipment and all the patents and converted it to a “soil nail launcher”. 2,500 psi is built up in a chamber and launches a nail at 220 mph into the unstable soil. These nails are typically between 12 and 20 feet long with a Super Launcher that penetrates up to 80 feet. The area is then left to nature or a shotcrete surface can be applied.
If you would like to see what intrigued me the most, go to their website: www.landslidesolutions.com to see what they have accomplished. Their services are averaging half of the cost of traditional “fixes”, they were approved by the California Coastal Commission, they have recently received a GSA (General Services Administration) contract number from the Federal Government for emergency services. They can solve geotechnical, construction and public safety problems.
A recent report by the geological society on the new faults found along the infamous San Andreas Fault causes serious doubt as to the earlier government findings of “acceptable standards” for construction, land use issues, and a host of other many other conclusions that must be reviewed. Many may need to be reconsidered and/or revised with this new information. Reinforcement may be the only logical solution.
Sunday, May 3, 2009
Turkish landslide statistics
Image from: http://www.panoramio.com/photo/20677530
Just a short post to point out some interesting statistics on rockslides in Turkey. The source of the data is the General Directorate of Disaster Affairs in Turkey, reported here. The statistics are:
Total area at risk from rockslides in Turkey: 194,000 square kilometres
Number of people at risk: 8 million (11% of the population)
Number of fatalities from rockslides between 1980 and 2000: 177.
Given the high seismic hazard in Turkey, these statistics are quite interesting.
An ancient tsunami in New York
The BBC are running a slightly strange story today about the possibility that the News York area was hit by a tsunami about 2,300 years ago. Given that by far the most likely source of a tsunami is a submarine landslide, this is of some interest. The odd part of this is the timing of the story - I cannot quite work out why it has popped up again now. A very similar story made the news in November last year - see here - and again in December (see here), so I can't quite see what has changed to bring this back to the forefront again. Perhaps a paper regarding this is about to be published - but there is no reference to this in the news report on the BBC.
The BBC news report focuses upon work being undertaken by Steve Goodbred and colleagues at Vanderbilt University in Tennessee. They have identified what appears to be a tsunami deposit from cores across New York and New Jersey. Tsunami deposits are interesting as the wave can transport coarse-grained particles (typically gravels) and even marine fossils from the near continental shelf to deposit them some way inland. Thus, they tend to be quite distinctive. Unfortunately, a major problem is that storm surges associated with very large storms can also bring in coarse shallow marine materials, which means that determining for sure that a deposit was generated by a tsunami is difficult.
In the case of the New York area, a quite extensive deposit has been found. Dr Goodbred and his colleagues suggest in the BBC article that this is probably a tsunami created by a submarine landslide, much like the 1929 Grand Banks (Newfoundland) event.
My sense is that considerable further work is needed here. First, we should all be distinctly pleased that there is no suggestion being made that this tsunami deposit was generated by the ludicrous hypothesis postulated a few years ago by Ward and Day that occasional flank collapses on the volcanoes of the Canary Islands can generate tsunamis that devastate the whole North Atlantic basin. However, the November 2008 news stories centred around a suggestion that a research team from Harvard and Colombia University had found evidence of an impact event origin for the tsunami deposit - i.e. that the wave was generated by a meteorite impact into the ocean. They claim that the deposit contains the types of particles that such an event would generate. I note that there does appear to be some difference in the size of the wave that the teams believe occurred - Goodbred suggests c.5 m, whilst the Harvard team suggest 20 m.
Personally I would like to see some peer reviewed publications on this before we make too much of it. There are a whole series of strands here that really need to go through peer review:
1. The structure of the deposit and its distribution;
2. Its age;
3. Analyses of its origin, looking in particular at its composition (particle mineralogies and sizes, fossil materials; etc), variations in its thickness, the presence of nano-diamonds that are supposedly indicative of an impact event, etc.
Of course the media interest in this is that the potential destruction of New York by a tsunami is rather exciting. We do need to understand Atlantic tsunamis rather better, but there is little doubt that they are really pretty rare and have rather localised impacts in terms of the tsunamis that they generate.
The BBC news report focuses upon work being undertaken by Steve Goodbred and colleagues at Vanderbilt University in Tennessee. They have identified what appears to be a tsunami deposit from cores across New York and New Jersey. Tsunami deposits are interesting as the wave can transport coarse-grained particles (typically gravels) and even marine fossils from the near continental shelf to deposit them some way inland. Thus, they tend to be quite distinctive. Unfortunately, a major problem is that storm surges associated with very large storms can also bring in coarse shallow marine materials, which means that determining for sure that a deposit was generated by a tsunami is difficult.
In the case of the New York area, a quite extensive deposit has been found. Dr Goodbred and his colleagues suggest in the BBC article that this is probably a tsunami created by a submarine landslide, much like the 1929 Grand Banks (Newfoundland) event.
My sense is that considerable further work is needed here. First, we should all be distinctly pleased that there is no suggestion being made that this tsunami deposit was generated by the ludicrous hypothesis postulated a few years ago by Ward and Day that occasional flank collapses on the volcanoes of the Canary Islands can generate tsunamis that devastate the whole North Atlantic basin. However, the November 2008 news stories centred around a suggestion that a research team from Harvard and Colombia University had found evidence of an impact event origin for the tsunami deposit - i.e. that the wave was generated by a meteorite impact into the ocean. They claim that the deposit contains the types of particles that such an event would generate. I note that there does appear to be some difference in the size of the wave that the teams believe occurred - Goodbred suggests c.5 m, whilst the Harvard team suggest 20 m.
Personally I would like to see some peer reviewed publications on this before we make too much of it. There are a whole series of strands here that really need to go through peer review:
1. The structure of the deposit and its distribution;
2. Its age;
3. Analyses of its origin, looking in particular at its composition (particle mineralogies and sizes, fossil materials; etc), variations in its thickness, the presence of nano-diamonds that are supposedly indicative of an impact event, etc.
Of course the media interest in this is that the potential destruction of New York by a tsunami is rather exciting. We do need to understand Atlantic tsunamis rather better, but there is little doubt that they are really pretty rare and have rather localised impacts in terms of the tsunamis that they generate.
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