We are recruiting a post-doctoral researcher to work on earthquake-induced landslides

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Professor Alex Densmore and I are currently recruiting a Post-Doctoral researcher to work with us on a project on earthquake-induced landslides. This post, which will start on 1st October 2013, is a two month position that is part of the consortium team on the ‘Earthquakes Without Frontiers’ project that is featured on this blog, funded by the NERC-ESRC Increasing Resilience to Natural Hazards Programme. As a reminder, the aim of the EWF project is to increase resilience to continental earthquakes across the Alpine-Himalayan mountain chain, through a linked trans-disciplinary partnership of physical scientists, social scientists, policy specialists, and regional and national partner organisations. This involves:

1. Characterisation of the physical earthquake hazard across the region, including better understanding of the locations of active faults and strain accumulation, as well as better assessment of the likely locations, extent, and long-term impacts of secondary hazards such as landsliding;
2. Assessment of pathways to resilience in the partner countries, including a full mapping of the societal, cultural, economic, and governance factors that enhance or erode resilience along with an understanding of existing efforts to build resilience and the ways in which that information has been used;
3. Development of effective policy and strategies for intervention to increase resilience to future damaging earthquakes.

This new post will contribute primarily to aspect (i), and will focus in particular on delivering an enhanced understanding of coseismic landsliding, and of new web-based forecasting tools for end-users. This work will comprise two separate strands:

1. Development of a process-based approach to the forecasting of coseismic landslides that improves upon current empirical approaches; and
2. Construction of a novel tool for tracking the temporal evolution of landslide material.

The work will be focused on three primary field areas: Nepal and northern India; southern Kazakhstan; and central China. The post-holder will be based in the Department of Geography, Durham University, but will be expected to work closely with team members at the other institutions within the consortium (Cambridge, Oxford, Leeds, Hull, Northumbria, the British Geological Survey, and the Overseas Development Institute), as well as with wider members of the partnership.

Full details of the post are available on the Durham University jobs website: http://www.dur.ac.uk/jobs/ or please feel free to email me at: d.n.petley@durham.ac.uk

A first analysis of the potential landslide distribution from the Iran earthquake

By Rob Parker (University of Cardiff) and Dave Petley

The Mw = 7.8 earthquake on Tuesday in Iran was the largest event in that country for about 50 years. Fortunately, the depth of the earthquake (82 km) and the low population density in the affected areas meant that loss of life was low for an event of this size.  Indeed, reports suggest that only one person died in Iran, although there are reports of 40 deaths in Pakistan.  This single fatality in Iran was the result of a landslide, and one of the images on the BBC reports about the earthquake also seems to show landslides:

http://www.bbc.co.uk/news/world-middle-east-22168202

Over the last three years or so, we have been working with our colleagues Alex Densmore and Nick Rosser, and funded by the Willis Research Network, to develop a model that will allow us to make an initial assessment of landslide impacts in earthquakes.  Rob recently submitted his PhD, and has now moved to a post-doctoral position at Cardiff.  However, we thought that this event would be an interesting first application of the model, which has been produced through a statistical (logistic regression) analysis of spatial patterns of landslides (with areas larger than 11,000 square metres) triggered by four large earthquakes in the USA, New Zealand, Taiwan and China. The model provides a first-order prediction of the probability of hillslope failure across the region affected by seismic shaking, based on the strength of ground motions and the gradient of hillslopes. Areas likely to have experienced high levels of landslide activity are shown in red, and while areas we expect to be less affected by landslides are shown in green and then blue. Here, landslide probability has been estimated using preliminary ground motion data published by the USGS and hillslope gradients derived from the ASTER global elevation model.

This is the outcome of the model:

We have a Google Earth kml of this that we can provide.  Unfortunately we cannot embed this in the blog, and we don’t have access to our ftp site until Monday.  Please email DNP at d.n.petley@durham.ac.uk if you want a copy of this.

Some notable features of the predicted landslide distribution are:

• The highest levels of landslide activity are predicted close to the epicentre, where ground accelerations were strongest;
• Higher landslide probabilities are predicted to the south-west of the epicentre, where there are higher levels of relief, and lower probabilities are predicted for lower relief regions to the north-east;
• Despite the high magnitude, the predicted impact of landslides is relatively low. This can be seen through a comparison of predicted landslide activity with that observed in other major earthquakes (see table  below). By aggregating predicted probabilities spatially, the percentage of hillslopes that undergo failure can be estimated. Table 1 shows a comparison of the predicted percentage area affected by landslides within 20 km of the epicentre, with that observed in three other earthquakes. Although the Tuesday’s earthquake has a magnitude similar to the Wenchuan earthquake, the predicted density of landslides is lower than that observed in the magnitude 6.7 Northridge earthquake. This is mainly due to the deep focus of Tuesday’s earthquake, which meant that surface ground accelerations were weaker than those produced by shallower earthquakes of this size.

Earthquake	Magnitude	Depth(km)	Percentage of failed hillslopes within 20 km of epicentre
2008 Wenchuan earthquake (China)	7.9	12.8	13.4 % (observed)
2013 Khash earthquake (Iran)	7.8	82	0.3 % (predicted)
1999 Chi-Chi earthquake (Taiwan)	7.6	8	1.1 % (observed)
1994 Northridge earthquake (USA)	6.7	18	0.5 % (observed)

A notable feature of this earthquake is the relatively low number of reported deaths (41 in the two affected countries).  The 2008 Wenchuan earthquake, which had a magnitude of 7.9 (i.e. it was similar to this event), caused around 80,000 fatalities, 20,000 of which were attributed to landslides. Similarly, the 2005 Kashmir earthquake in Northern Pakistan (magnitude 7.6) resulted in over 80,000 fatalities. Underestimates of damage and fatalities are common in the immediate aftermath of large earthquakes, particularly in remote areas, and the death toll may change over the coming days. However, the epicentral region has a relatively low population density compared with areas affected by the Wenchuan and Kashmir earthquakes:

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Estimates from 2008 suggest a total population of around 4 million within the area covered by our landslide model above. The death toll is therefore unlikely to rise to the levels seen in Wenchuan and Kashmir, where population densities are much higher.  It is this low population density, combined with the very large depth of the earthquake, that has meant that the loss of life is so low.  A similar, but shallow, earthquake in a more densely populated area would have had very different outcomes.

It is of course vital to say that this is just a first order estimation, and we will need to examine the actual distribution as images become available.

Reference
Bright EA, Coleman PR, King AL, Rose AN, Urban ML. LandScan 2008. 2008 ed. Oak Ridge, TN: Oak Ridge National Laboratory; 2009.

The EwF Launch in Kathmandu, Nepal

Katie Oven and Susanne Sargeant  

January 16^th saw the launch of the EwF project in Kathmandu, Nepal.  Hosted by the National Society for Earthquake Technology (NSET-Nepal), the event brought together more than 25 national-level stakeholders involved in earthquake risk reduction in Nepal including representatives from government ministries and departments; international organisations including the UNDP; donors including the World Bank and DfID; NGOs; and universities.

Following speeches from Mr Navin Kumar Ghimire (Secretary, Ministry of Home Affairs) and Mr Chakrapani Sharma (Under-Secretary, Ministry of Federal Affairs and Local Development), time was spent exploring the aims of the EwF project in Nepal, India and the wider partnership, beginning with a presentation from Alex Densmore.  This was followed by our local partners (the Nepal Risk Reduction Consortium, NSET-Nepal, and the International Centre for Integrated Mountain Development) who outlined some of the physical and social science research needs of the stakeholder community and offered valuable suggestions as to how the EwF project could feed into on-going work around earthquake risk reduction in Nepal.  A workshop in the afternoon provided an opportunity for a smaller group to work together to identify key national-level stakeholders engaged in this area and to explore relationships of power and influence.          

The EwF launch in Kathmandu, Nepal

Unlike India, with its clear government structure and institutional framework for disaster risk reduction (DRR), international organisations, NGOs, and donors have been driving the DRR agenda in Nepal.  In line with Nepal’s commitment to the Hyogo Framework for Action, a National Strategy for Disaster Risk Management has been drafted, but this remains a strategy only with no formal legislative framework for DRR.

Despite this political impasse, progress is being made.  The Nepal Risk Reduction Consortium (NRRC) provides the structure for action in Nepal by uniting humanitarian, development and financial partners with the Government of Nepal. The NRRC is structured around five flagship priorities: School and Hospital Safety; Emergency Preparedness and Response; Flood Risk Management and in the Kosi River Basin; Community Based Disaster Risk Reduction; and Policy/Institutional Strengthening.  The EwF project will be working closely with the NRRC with a view to informing their programmes around earthquake risk reduction.  We will also be sharing the learning from Nepal with other countries in the wider EwF Partnership.

During our time in Nepal, we have seen many examples of awareness raising, training and capacity building activities at the municipal/community level, and have taken part in some of these activities.  Examples include NSET’s Earthquake Safety Day which saw more than 2,000 people from NSET, the Red Cross, police and other organisations participate in an awareness raising rally in Bhaktapur City; street theatre in Kathmandu to raise awareness around earthquake safe building construction; training for local masons; and retrofitting programmes in schools.  Working with our local partners, the EwF team are exploring ways that natural and social scientists, and their research and expertise, might inform these types of activities to create a more earthquake resilient Nepal.

Members of the EwF Team participate in the Nepal Earthquake Safety Day rally

The EwF Project Launch in Patna, Bihar State, India

“Punarnava”: Bouncing back to life again and again

Samantha Jones and Katie Oven

The EwF launch in Patna, in the Indian State of Bihar, took place this week.  Hosted by the Bihar State Disaster Management Authority, the launch was attended by 25 stakeholders involved in earthquake risk reduction in Bihar including government departments, international organisations, NGOs, and local universities and research institutes.  The launch event provided an opportunity to identify and map out key stakeholders involved in earthquake risk reduction, and to discuss the aims of the EwF project in India and Nepal, along with the wider EwF partnership.  Local stakeholders shared examples of resilience building activities underway in Bihar at both the state and local (district and community) levels. There was some preliminary discussion around research needs and opportunities for collaboration with the EwF project.

The EwF launch in Patna

The key legislation around disaster risk management (DRM) in India was passed in 2005 (the Disaster Management Act) by the National Government.  Key drivers for policy change include past disasters (the 1999 cyclone in Orissa, the 2001 Gujarat earthquake, and the 2004 tsunami) and international frameworks such as the Hyogo Framework for Action.  The legislation provides an outline of new structures, roles and responsibilities for DRM but this has only been institutionalised in Bihar in the last four to five years, primarily through the establishment of the BSDMA.

Bihar has long been described as a lawless, backward state.  The new government, with its visionary Minister, has generated a sense of optimism amongst stakeholders.  As noted by one participant: key people are currently in the right positions to forward the earthquake risk reduction agenda.  In the last two to three years there is increasing evidence of awareness raising, capacity building and training in the context of earthquake risk reduction at the state, district and community levels.  However, while resources are not considered to be a major constraint, DRM expertise, is acknowledged to be lacking.  There are currently no building inspectors to enforce building codes (even though these exist).  This has been attributed to a lack of knowledge among architects, engineers and masons and is a priority area currently being addressed by the BSDMA.

Active faults in northern China and some rather cold fieldwork

By Tim Middleton, PhD student at COMET+, Department of Earth Sciences, University of Oxford

Inner Mongolia is cold in November. Snow and ice blanket the elevated plateau and the biting winds drag the temperature well below minus 20°C. An enormous wind farm, recently installed by the local government, makes good use of the extreme weather. Herdsmen are dressed in fur coats and ski goggles, whilst other locals hack at frozen bales of hay with pickaxes. Perfect conditions, then, for a field trip examining the active faults!

Figure 1: East-west strike-slip fault in Inner Mongolia with a small component of vertical motion to produce the scarp visible in the photograph (possibly the result of a single palaeo-earthquake rupture). The fence crossing the scarp clearly indicates the height difference. Drainage has ponded against the scarp leading to greater vegetation cover on the northern side of the fault.

At the end of November 2012 a small group of researchers (Dr. Richard Walker from the University of Oxford, Dr. Weitao Wang from the Institute of Geology at the Chinese Earthquake Administration and I) spent a busy week doing reconnaissance fieldwork in northern China. We were particularly interested in two things: the possible presence of active strike-slip faults in Inner Mongolia (the northernmost province in central China), and the determination of slip rates on the active normal faults in the northern Shanxi grabens.

Figure 2: Topographic map of north central China. Beijing is just visible on the eastern edge of the map. Topographic data is from ASTER GDEM; GPS data is from Wang et al., 2002; focal mechanisms are from the CMT catalogue. Black lines indicate active faults and are drawn with the aid of topographic data and satellite imagery. A major strike-slip fault is visible to the northwest of the map, whilst the northern Shanxi grabens are shown towards the south of the map.

Up on the Inner Mongolian plateau, large areas are covered by Cenozoic basalt flows and the landscape is spotted with volcanic cinder cones. A number of the faults cut these flows and by determining the ages of the basalts we hope to be able to place constraints on the rate of motion of these faults. It is also interesting to note that the majority of the cinder cones form belts that trend northeast-southwest, parallel to the normal faults in the northern Shanxi. Tapponnier and Molnar (1977) suggest that this is to be expected given the overall northwest-southeast extension in the region.

Figure 3: Northeast-southwest trending basaltic cinder cones. The same cones were visible from the window of our plane as we flew into Beijing!

After our sojourn to the freezing north, we moved south to the relatively balmy minus 5°C of Hebei and Shanxi provinces to visit the northern Shanxi grabens. This graben system constitutes the northern portion of the extension that is occurring along the eastern edge of the Ordos Plateau. It comprises a mixture of complete grabens—with intervening horst blocks—and tilted half grabens.

Figure 4: Topographic profile across the footwall of the fault on the southeastern side of the Datong Graben. The profile clearly shows the classic tilted block morphology expected of a half graben.

We visited graben-bounding faults on the northwest side of the Datong Graben, the southeast side of the Datong Graben and the southern side of the Yuxian Graben. At each site we took samples from loess deposits immediately overlying uplifted river gravels in the footwalls of the faults. By using optically stimulated luminescence (OSL) dating, we hope to be able to determine the rates of motion on these faults. In some locations we even found exposed sections of the fault plane, allowing us to measure its strike and dip. This will enable us to convert our vertical rates of motion into slip rates in the plane of the fault.

Figure 5: Exposed normal fault on the southern side of the Yuxian Graben. The contact between river gravels and the overlying loess is visible on both sides of the fault, allowing us to estimate the throw on this portion of the fault.

Along one arm of the Datong Graben the topographic data suggests that a new fault is growing in the centre of the basin. We drove past one evening and were rewarded with a stunning sunset view of the fault scarp, looking across the Sanggan River.

Figure 6: Sunset over the Sanggan River. The river is important because it supplies much of Beijing’s water. It also features in Ding Ling’s 1948 novel “The Sun Shines over the Sanggan River”, a reflection on the life of peasants at the time of land reform in northern China.

Few earthquakes have severely affected this part of China in recent history, but the faults we saw on this trip show clear evidence of Quaternary activity. Hopefully we will be able to learn a lot more about them on future trips—perhaps when it’s slightly less cold!

With thanks to Dr. Weitao Wang and the Institute of Geology at the Chinese Earthquake Administration.

Initial reports of landslides from the 7th November 2012 M=7.4 earthquake in Guatemala

The M=7.4 that struck just offshore western Guatemala yesterday is now believed to have killed at least 48 people, with more people thought to still be buried in the rubble.  The location of the epicenter of the earthquake, as measured by the USGS, indicates that there is high ground within the area that might be expected to have suffered high peak ground accelerations (as the Google Earth perspective view below shows), indicating that landslides are likely:

Inevitably, the area affected by landslides is both remote and inaccessible in the aftermath of the earthquake, so a proper understanding of the landslides will take some time.  In the meantime, there is some evidence that landslides have been a significant problem.  The BBC has two images that show landslides.  The first appears to be a simple rockslope failure:

http://www.bbc.co.uk/news/world-latin-america-20247046

Whilst the second is a slope failure in an aggregate quarry that is reported to have claimed seven lives:

http://www.bbc.co.uk/news/world-latin-america-20247046

The Washington Post has another picture of what I assume is the same site:

http://www.washingtonpost.com/world/the_americas/powerful-earthquake-strikes-guatemala-border-area-near-mexico-killing-at-least-39-people/2012/11/07/90306926-2939-11e2-aaa5-ac786110c486_story.html

More images of the landslides will probably emerge in the next day or so.

 

Moving mountain and steppe, Kazakhstan

Kazakhstan is a final frontier in understanding Central Asian neotectonics related to the India-Eurasia collision. This vast, enigmatic country comprises many major active faults and consequently is no stranger to earthquakes, having suffered a series of catastrophic events within the last 125 years. Despite this stark earthquake hazard, there is a need and opportunity to develop an understanding of this region through integration of fieldwork with modern space-based observations from satellite imagery, Global Positioning System (GPS)  networks and Interferometric Synthetic Aperture Radar (InSAR).
Our observations of high resolution satellite imagery and in the field not only reveal many
previously unidentified major active faults (defined as those which offset late Quaternary features such as abandoned alluvial fan surfaces) but also a majority of other large faults that although are recognised structures, are not considered active. Essentially, nothing is known of the earthquake repeat times or slip rates on these faults, which due to their close proximity to towns and highly populated cities, pose a very serious and realistic seismic hazard.

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If we hope to help increase Kazakhstan’s resilience to earthquakes and their hazardous secondary effects such as landslides, a first step must be to properly identify and characterise in detail the seismogenic faults of this country.

Topographic map of eastern Kazakhstan, showing the major active faults (black lines), and the z-shaped Paleozoic mountain spine (pink ‘Z’). Topography is greyscale (lighter = higher elv.)

The focus of our research lies in eastern Kazakhstan (Fig. 1), a region characterised by several different mountain range orientations, which together form a Z-shaped Paleozoic mountain spine spanning over 800 km from S to N. The different ranges are interspersed amongst rolling, golden steppe-land and late Cenozoic sedimentary basins. This unusual mountain-range configuration is controlled by the active tectonics of the region. Major strike-slip faults extend for hundreds of kilometres, cutting through the high mountains and often radiating from the high mountains into the flat desert plains of the Kazakh platform (Fig. 1). We find that right-lateral faults are predominantly oriented NW-SE, and left-lateral and reverse faults are predominantly orientated E-W. Movement on these faults, particularly since the beginning of the most recent period of mountain building
activity (~25 Ma), has resulted in the stunning 4,000 m snow-capped peaks of the Ili-Alatau and Dzungar-Alatau mountain ranges. These same fault movements have also resulted in devastating earthquakes such as the 1911 Chon-Kemin event (Mw ~8.2), which destroyed Kazakhstan’s former capital city, Almaty.

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The scientific team this September consisted of five UK researchers (Dr. Richard Walker and two first year PhD students David Mackenzie and Tim Middleton from Univ. Oxford, and Prof James Jackson and myself, from Univ. Cambridge) and Professor Kanatbek Abdrakhmatov, Director of the Institute of Seismology in the Kyrgyz Republic National Academy of Sciences, Bishkek. Also on-board was expert off-road driver (Ivan) and camp manager/cook (Inagul). The Institute of Geophysical Research, National Nuclear Centre of the Kazakhstan Republic supported our trip and hosted us in Almaty. We also had a promising first meeting with academics from the Kazakh British Technological University (KBTU), Almaty, who this year, for the first time have opened a Department of Geology.

The ~7-10 m vertical scarp cuts through Paleozoic mountain ridges in the high Dzungar-Alatau in the faults eastern extent, there is also a ~3 m right-lateral component. This overall offset has blocked drainage forming inter-ridge ponds.

A major component of our work this summer involved making a detailed investigation a major fault, which extends over 100 km E-W from the high Dzungar-Alatau mountains into the flat Kazakh platform. Along the faults length, a consistent ~7 to 10 m scarp is impeccably preserved offsetting Paleozoic mountain ridges (Fig. 2) and along the range front in its eastern extent, and as a single ~7 m vertical step within otherwise flat-lying, vegetated desert loess in its western extent (Fig. 3).  Along the length of the fault, ponds have formed where drainage is blocked by the vertical offset. In particular we were interested in a ‘ghost’ river channel which was abandoned by uplift on this fault (Fig.4).
Based on the continuity and consistency of the scarp height over the entire fault-length it is likely that this fault scarp was formed during one very large, catastrophic earthquake. To test this hypothesis, we collected sediment samples from the base of several dried-pond sites in the east and west of the fault and from the abandoned ‘ghost’ river channel. If this was indeed one event, then the ages of these samples should be the same. Using the date of this event and quantitative measurements of the amount and sense of displacement found using field-surveyed digital elevation models (DEMs) we can calculate a minimum late Quaternary slip-rate, which will provide the first ever constraint on the seismic hazard of this fault.

Digital elevation data highlights the ‘right angle’ fault termination in the Kazakh Platform. This fault geometry and offset has caused the abandonment of a river channel in which flow orginally ran from N to S. The offset caused by this paleo-earthquake blocked the original drainage, forming ponds against the upthrown (S) side.

Closer to Almaty, we made preliminary field observations of a major right-lateral strike-slip fault, Dzhalair-Naiman (Fig. 1), which extends over 400 km NW-SE into the Kazakh Platform, and finally we conducted several slip-rate studies along the E-W oriented Zailisky-Alatau range front (part of the Ili-Alatau mountain range) which forms the snow-capped backdrop south of Almaty. In particular, the fault scarps investigated at these final sites may be potential paleo-rupture candidates for the historic Mw ~7 to 8 earthquake which devastated Almaty (formerly Verny) in 1887.