Most of the world's large earthquakes happen on the plate boundary faults at subduction zones where two plates converge (e.g. Sumatra in 2004, 2005, and 2007; Chile in 2010). Because the parts of these faults that move during the earthquake lie underwater, they can also be the source of major tsunami. However, different subduction zones are subject to different sizes of earthquakes, and different patterns of earthquake rupture, so that the hazards vary significantly. In most cases rupture on the plate boundary faults is limited to a zone where the fault lies from ~30-40km up to ~5-15km beneath the seabed, but in some cases the fault rupture is thought to have been much more extensive and potentially to have reached the seabed. In other cases the faults are sometimes seen to move more gradually, without an earthquake. In other cases (e.g., Nankai margin offshore Japan), movement on the main plate boundary fault is affected by faults within the accretionary prism, that forms as sediment is scraped off the downgoing plate, and these faults may slip affecting the size of the tsunami waves generated. A final major problem with knowing these hazards at a given subduction zone is that the biggest earthquakes normally only occur every few hundred years, so that our records of the effects are very incomplete. These different fault behaviours depend on the physical properties of the faults themselves, controlled by the seabed sediments adjacent to the subduction zone, and factors such as the presence of fluids within the fault. One way to determine these properties, and presence of fluids, is to drill into the fault zone and directly take samples or measurements of the rock properties using 'logging' technology; this has been done in several places round the world, but even with the most modern technology (riser drilling), it is only possible in the shallower parts of faults, and generates a set of observations effectively at a single location. Drilling at a number of different places on subduction zones together with associated seismic experiments (that bounce sound waves off structures within the earth) show that these properties are very variable, within a single region, and between regions. This reinforces that the combination of drilling (providing local detailed information) and seismic data (providing regional information) should be the primary method for assessing fault properties and their hazard potential: the technique employed in this project. We aim to better understand the behaviour of subduction zone faults by combining seismic and drilling data from several subduction zones around the world. We have chosen regions which have contrasting thicknesses of sediments, and where known fault activity and type and size of resulting earthquakes vary. We will use the drilling data to increase our ability to interpret the properties and fluid content of the fault zones from seismic data at the same location. Then using the seismic interpretations to extend our knowledge of the fault zones over much broader regions, we will investigate variations both down and along the plate boundary fault. We will use the same methods to investigate the relationship between the main plate boundary fault and smaller faults within the accretionary prism. We will then extend our analysis to regions where seismic data have been collected, but which have not yet been drilled, including margins offshore Sumatra and New Zealand. The results generated by the project will allow drilling on these new margins (Sumatra and New Zealand) to be targeted more effectively, thus obtaining new samples and measurements from the sections of these subduction systems with greatest significance for earthquake generation. Ultimately we will relate the interpretations of the state of the plate boundary faults to the known earthquake behaviour and tsunami history, aiming to improve assessments of the hazards at other locations where the long-term behaviour is not known.

Predictions of future climate, essential for safeguarding society and ecosystems, are underpinned by numerical models of the Earth system. These models are routinely tested against, and in many cases tuned towards, observations of the modern Earth system. However, the model predictions of the climate of the end of this century lie largely outside of this evaluation period, due to the projected future CO2 forcing being significantly greater than that seen in the observational record. Indeed, recent work reconstructing past CO2 has shown that the closest analogues to the 22nd century, in terms of CO2 concentration, are tens of millions of years ago, in 'Deep-Time'. The Palaeoclimate Modelling Intercomparison Project (PMIP) provides a framework (but no funding!) by which the palaeoclimate modelling community assesses state-of-the-art climate models relative to past climate data. Traditionally, PMIP has focussed on the relatively recent mid-Holocene (6,000 years ago) and Last Glacial Maximum (21,000 years ago), but these time periods have even lower CO2 than modern (~280 and ~180 ppmv respectively, c.f. ~400 ppmv for the modern). Recently, PMIP has expanded into other time periods, most notably the mid-Pliocene (3 million years ago), but even then, CO2 was most likely less than modern values (~380 ppmv). The modelling community would clearly benefit from an intercomparison of 'Deep-Time' climates, when CO2 levels were close to those predicted for the end of this century. We will organise and provide funding for 2 workshops, with the aim of producing papers describing the experimental design and outputs from a new climate Model Intercomparison Project - "DeepMIP", focussing on past climates in which atmospheric CO2 concentrations were similar to those projected for the end of this century. The papers will evaluate the models relative to past geological data, and aim to understand the reasons for the model-model differences and model-data (dis)agreements, providing information of relevance to the IPCC. A previous NERC grant, NE/K014757/1, is currently aiming to assess climate sensitivity (the response of surface air temperature to a doubling of atmospheric CO2), through geological time. That project is focussing on many time periods, but with only one model. This IOF will complement that project, and bring added-value, by focussing on one particular time period, but with many models. As such we will address the crucial issue of model-dependence.

PROJECT SUMMARY As a result of continuous burning of fossil fuel, the global environment is facing a crisis stemming from rapidly rising concentrations of carbon dioxide and other greenhouse gases in our atmosphere. Assuming greenhouse gas emissions at or above current rates, carbon dioxide will reach nearly triple the pre-industrial concentrations by the end of this century. This is expected to raise global mean temperatures to a level not seen for more than 32 million years. According to the latest assessment of the Intergovernmental Panel on Climate Change, the high latitudes will experience the largest temperature increases, resulting in a rapid melting of polar ice-sheets and global sea level rise. For a further understanding of potential changes that our world may undergo in the future, it is vital to study environmental changes during past warm periods and across major climatic thresholds. The proposed research project will reconstruct past vegetation of Antarctica and southern Australasia during the Eocene (ca 55-34 million years ago). The Eocene is a geological time period of exceptional warmth, with atmospheric CO2 concentrations exceeding triple the pre-industrial levels. The project will reconstruct past vegetation by analysing pollen in sediments deposited during Eocene times. Vegetation provides detailed information on a number of important environmental parameters, such as annual temperature and precipitation, length of growing season, minimum and maximum temperatures, and soils. Of particular interest for this study are very short-lived time intervals during the early and late Eocene, during which carbon dioxide concentration and temperatures changed rapidly. For a full understanding of their climate forcings and mechanisms, the analysed sediments must have a high time resolution and unambiguous dating control, in order to relate them to respective past climate events. The marine cores 1171 and 1171, taken offshore Tasmania as part of the International Ocean Deep Drilling Programme Leg 189, as well as Eocene rock outcrops at Cape Foulwind in New Zealand, have been chosen for the proposed study, as they provide an unprecedented opportunity to produce high resolution pollen records for Antarctica and adjacent sub-polar regions. The data will be interpreted in a global context and related to Arctic palaeoenvironmental reconstructions by integrating them into the global GIS database TEVIS (Tertiary Environment and Vegetation Information System). The TEVIS dataset will be compared with a number of simulations using the cutting edge Hadley Centre climate model (used within the climate assessment reports of the Intergovernmental Panel of Climate Change IPCC). By combining regional high-resolution pollen analyses with global data-model comparison, this proposed study will foster a deeper understanding of how the terrestrial environments and polar ice sheets responded, and might respond in the future, to rapid changes in temperatures and atmospheric CO2 concentration. By indicating weakness and strength, the data-model comparison will also contribute to the improvement of climate models that we rely upon for simulating future climate change.

The Sichuan earthquake in mid-May killed more than 87,000 persons and caused damage on the order of fifty billion pounds. Much of the damage, and further loss of life, resulted from aftershocks - smaller earthquakes triggered by the occurrence of the M7.9 mainshock. Research over the past 15 years or so has increased our understanding of aftershocks and particularly of the controls on their locations. The most important realisation is that large earthquakes induce stress changes in the surrounding crust which can be calculated within a few hours of the mainshock; areas of stress increase correlate strongly with the occurrence of aftershocks. (These 'Coulomb' stresses are computed by resolving the tensorial stress perturbation into shear and normal components on planes of interest; increased shear stress and decrease normal stress encourage failure.) Maps of such stress changes can be used to inform emergency response so that, for example, evacuation shelters are sited in areas where stress has decreased and hence aftershocks are not expected. More useful information for emergency services would be an estimation of the probability of an earthquake above a particular magnitude affecting any given location. Calculating such probabilities is not straight-forward, however, as the only model that directly relates stress and probability changes is based on laboratory friction experiments and relies on a number of assumptions that may not be realistic as well as the determination of a number of poorly constrained parameters. To date, this model has only been subjected to one systematic test and the results were inconclusive. An alternative approach to estimating aftershock probabilities is purely statistical, based on two key observations: the Gutenberg-Richter relation which describes the number-size distribution of earthquakes and the Omori law for decrease in aftershock numbers with time. In a recent test on a single aftershock sequence, the abilities of 7 statistical and 4 stress-based models to forecast probabilities were rigorously tested. Surprisingly, the statistical models fared best, despite their lack of the essential physics that controls the spatial distribution of aftershocks. The reason for this result is open to interpretation, but the stress-based models may have suffered because of the failure of the unphysical assumptions in the friction law or because the required parameters were not estimated correctly. Alternatively, because in this model the expected rate of aftershocks depends on the magnitude of the stress change, there may have been problems with the calculated stress field due to un-modelled small scale heterogeneity in the earthquake slip distribution. The aim of this project is to develop a combined stress/statistical model for aftershock occurrence and rigorously test it against statistical and stress-based models as well as several simple reference models. This new model will retain the important spatial controls that result from the stress perturbation but will circumvent the difficulties associated with the rate-state approach. If successful, we will have a new method for calculating aftershock probabilities.