I was in a motel in Albuquerque when the devastating magnitude 7.9 earthquake struck Sichuan, China on 12 May. However, thanks to the Internet I was in touch with events and a few hours after the event I downloaded the map below (from the website of US Geological Survey Earthguake Hazards Program). This captures all earthquakes above magntiude 2.5 on the Richter scale in the previous 7 days. The only magntiude 7 quake in that week was the one in Sichuan (marked by a large orange square). Already there had been a magnitude 5 aftershock, shown by the superimposed red square, the red colour denting an event less than one hour before I captured the map.

Earthquakes on 12 May 2008.
[Map courtesy of United States Geological Survey]

After seeking out some other basic information on this event, I wrote some quotes for the British media, disseminated by the excellent Science Media Centre. I explained how the quake had been both large and relatively shallow (which probably accounted for the violence of the ground motion and the extent of the damage) and explained that the quake was a consequence India's plate tectonic collision with Asia, which is squeezing Tibet eastwards over the Sichuan Basin. On the next day, I was pleased to find that some of my material had been used by The Times. 'So, Tibet fights back' posted one wag in the on-line comments section.

That made me smile, but  the earthquake was, of course, a terrible tragedy. The official death toll has now exceeded 65,000, making it a close rival to the cyclone that recently hit the Irrawaddy delta in Burma. Fortunately, the Chinese rescue and relief effort seems a good deal more effective than what the Burmese government has managed to do, even though hampered by contunuig aftershocks - smaller than the initial quake, but big enough to collapse already-damaged buildings.

Today's map shows yet another in a the long series of aftershocks in the same region.

Earthquakes on 27 May 2008.
[Map courtesy of United States Geological Survey]

What really depresses me though is the disproportionate loss of life among school children. This is such a common story in many parts of the world; schools are built with inadequate resilience to earthquake shaking, not through ignorance but through corruption. I discussed this in my book Teach Yourself  Volcanoes, Earthquakes and Tsunamis, which forms the basis of the Open University's Volcanoes, Earthquakes and Tsunamis short course:

School buildings have often proved unstable in earthquakes. They are built at the public expense, usually as a result of competitive tendering with the construction firm that offered the cheapest deal being given the contract. Without conscientious enforcement of seismic building codes tragedy can ensue, as at San Giuliana di Puglia in 2002 where poor-quality masonry walls and a heavy reinforced concrete roof contributed to the collapse of the school. Following this event, the Italian government ordered an evaluation of the seismic vulnerability of all public buildings, such as schools and hospitals. Similar lessons were learned in Venezuela when two schools, built in contravention of the local seismic building code, collapsed as a result of a M7.0 earthquake on 9 July 1997 killing 46 students. In Algeria a M6.8 quake on 21 May 2003 left 122 schools in need of rebuilding. School-house tragedy was avoided in this case because the quake happened after the end of the school day, though 2287 other people died. However a M6.4 earthquake in eastern Turkey on 1 May 2003 brought down the roof of a school dormitory, killing many children as they slept. A subsequent survey found that none of the local schools accorded with the 1998 Turkish Seismic Code, and the blame for this was placed on lack of resources to supervise building works, and on poorly-trained architects and engineers. A similar story is likely to emerge concerning the collapse of school buildings during the Kashmir earthquake of 2005.

The same lessons keep being learned, and then ignored. In the next edition, I can foresee that I'll be adding in a damning comment about Chinese flouting of building codes.

Take it further

Volcanoes, earthquakes and tsunamis

Teach Yourself Volcanoes, Earthquakes and Tsunamis by David Rothery
published by Hodder Education

About the author

Dave Rothery is a volcanologist and planetary scientist at the Open University. His current research includes studying volcanic eruptions on the Earth and characterising planetary surfaces, especially Mercury.

Subscribe to Dave Rothery's posts

 

A two hour drive and a 40 minute boat ride along the Ganges north of Calcutta is Green Island. As the name suggests this is an island where the original vegetation that once covered the Ganges Delta remains relatively undisturbed.  I say relatively because while human disturbance is limited, every year when monsoon storms and high tides swell the river level Green Island is flooded, sometimes to a depth a little over a meter.

Studying this type of vegetation is crucial to my work as it represents exactly the kind of plant community that has the potential to be preserved in the fossil record. As the floodwaters scour the leaf litter from the soil surface, and the island margins are eaten away by erosion, leaves are washed into the river where they may be deposited in muds and silts and eventually fossilised. We see many such deposits in the rock record from which we deduce information on past vegetation and climate.

I was in the company of Professor Subir Bera from Calcutta University and his wife who had organised the day. We had special police permission to visit and collect on the island and even had a police escort. On the boat with us were several people from the nearby village who had (as we discovered later) prepared a wonderful lunch of fish and meat curries, rice and fruit, all served on banana leaves.

As the open wooden boat neared the island we could see whole trees, still with green leaves, that had recently fallen in to the water as the riverbanks were eroded. Caught in the branches of one such tree was the body of a goat. Now for most this might seem gruesome but for me it was fascinating because it was another example of taphonomic processes – taphonomy is the study of fossilisation.

As the Ganges undercuts the edges of Green Island whole trees fall into the river - perhaps on their way to being fossilised.
[Photo © copyright Bob Spicer]

Green Island is a little over a kilometre in length and a few hundred metres wide. Here we collected the populations of leaves from 56 different species of trees shrubs and vines. After pressing, drying and mathematically scoring them CLAMP analysis positioned the Green Island vegetation near the Kerala sites we had previously analysed, but in an area of the three-dimensional plot that indicated they were from a slightly cooler site.

Because Green Island is on a flat delta plain I could use meteorological data in the form of a grid in which observations from individual meteorological stations can be interpolated (mathematically extrapolated) for sites such as Green Island that does not have its own measurements.

CLAMP showing the positions of modern forests determined by their leaf architecture.

The plot above shows the positions of the Indian forests that I have analysed so far. In this plot each ball represents a forest. Green Island is Labelled “Green” and the other labelled balls are forests in Kerala. The positions of balls are determined by the numerical score that describes leaf architecture for at least twenty species of woody trees, shrubs and vines from each forest.

Balls that plot close together indicate forests with similar leaf architectures, while that that plot far apart are very different. The balls are colour coded such that blue represents cool climates and red ones hot climates. Orange, green and light blue indicate forests growing in intermediate climates. It is easy to see that the Indian forests (coded maroon) all lie in the warm end of the plot.

In this plot the Indian forests have been treated as if they were fossils. They have found their own position with respect to the other sites for which the climate is known. Despite the fact that the Indian sites all plot close to other warm sites they form a group beyond the limits of the existing cloud of sites, and using this calibration all the Indian sites yield a climate prediction that is several degrees colder than that which is observed.

The next stage is to include the Indian observed climate information so that the shape of the plot will change and the ability of the method to give accurate results for fossils that represent ancient forests growing in warm climates does not suffer from the same error of underestimating temperatures.

About the author

Bob Spicer is Professor of Earth Sciences at the Open University. Founding Director of the OU's Centre for Earth, Planetary Space and Astronomical Research (CEPSAR) his interests are broad. However he is most at home when studying how plants can be used to tell us about ancient climates, and how that information can help us plan for managing our planet in the future.

Subscribe to Bob Spicer's posts

 

For the past week or so the daily maximum temperature in Lucknow has been above 40 °C. Yesterday it was 42°C, and more of the same is forecast for the next five days. In these temperatures the demand for electricity to power air conditioning units exceeds supply and we have experienced frequent outages sometimes lasting hours. Without electricity to drive pumps, the water supply also fails.

It is sobering to think that in a warming world such events are bound to become more commonplace, not just here but across all the lower latitudes. We in the UK will not be immune either as summer heatwaves like that of 2003, which claimed so many lives across continental Europe, are forecast to increase in frequency and severity.

To help improve those forecasts we have been working on improving the warm climate performance of a technique that uses leaf architecture as a proxy for temperature and rainfall. By applying this technique to fossil leaves we can better quantify ancient climates, many of which were warmer than now, and thereby learn how climate might behave in the future.

Normally solitary, giant squirrels are
rarely seen together except about
breeding time.
[Photo © copyright Bob Spicer]

Recently I sampled six forests in Kerala, south India. At a latitude of around 9.5 °N they are well within the tropical zone, yet unlike many low latitude areas, they also experience marked variations in rainfall due to the influence of the Asian Monsoon. They never really dry out though, and so those lush forests host a large number of leeches that make sampling leaves a somewhat bloody affair. Apart from leeches the forests also support a rich variety of animal life such as giant squirrels (Ratufa indica), deer, and even wild elephants. Although Kerala promotes itself as a “green” state there are precious few undisturbed forests remaining. Most have been destroyed to plant tea and the destruction continues as multinational corporations have the power to buy up land and overpower conservation efforts. Soon there will be very little natural vegetation left save for a few protected reserves, with a consequent loss of biodiversity. Of course Kerala is not alone in losing its unique heritage this way, but it is particularly depressing to witness it first hand.

Tea plantations replace natural forest diversity, leaving only a few remnant trees as witnesses to what once was.
[Photo © copyright Bob Spicer]

Leaves from each of these modern sites are numerically scored and analysed using a technique called CLAMP. Results so far show that all the Kerala sites form a coherent cluster in a new area of what we call “physiognomic space” and thus provide opportunities for recalibrating CLAMP for low latitudes, both now and in the past.

This is exactly what we were hoping for. Now I am in the process of collecting and collating decades worth of weather observations for these areas so that the calibration process can take place. At least I will continue to do that if the power stays on and the computers don’t overheat.

About the author

Bob Spicer is Professor of Earth Sciences at the Open University. Founding Director of the OU's Centre for Earth, Planetary Space and Astronomical Research (CEPSAR) his interests are broad. However he is most at home when studying how plants can be used to tell us about ancient climates, and how that information can help us plan for managing our planet in the future.

Subscribe to Bob Spicer's posts