The Bowland Shale, England, contains ~1,300 trillion cubic feet of shale gas, a recoverable resource worth hundreds of billions of pounds over coming decades. If this resource is exploited, it must be done so using hydraulic fracturing ('hydrofracturing'), where fluids are injected at high pressure into the rocks to create fractures through which the gas can move. This process has transformed the USA into a gas exporter and dramatically reduced prices worldwide. Nevertheless, hazards arise from this process: hydrofracturing, alongside mining and carbon capture and storage, may induce earthquakes, which if large enough, can cause shaking at the Earth's surface that leads to damage. To mitigate the risk of such earthquakes to people and infrastructure, regulators demand that operations halt if earthquakes above a certain magnitude occur in a 'traffic light' system. However, existing methods used to characterise earthquakes do not account for the possible range of magnitudes, meaning that there will be cases where operations are incorrectly permitted to continue (or are halted) based on random variation or bias in the earthquake parameter estimates. 'False alarms' would lead to millions of pounds of lost income whilst damage from unexpected seismic events would be equally costly-and it is not even known which of these outcomes is rendered more likely by errors in earthquake magnitudes. Recent work shows that errors in event locations may be many times the stated uncertainties, directly impacting earthquake magnitude estimates. More broadly, earthquake magnitudes and locations estimated routinely by geological surveys worldwide suffer from similar trade-offs. In this technology-led proposal, we propose a new method to estimate jointly the seismic velocities of the subsurface and the locations of observed microearthquakes while varying attenuation, by using recordings from an array of seismometers at the surface. Such an arrangement is advantageous for cost and speed purposes, though is limited by uncertainty in the properties of the subsurface between the earthquakes and the stations. This fully non-linearised approach allows for the first time to calculate true tradeoffs between earthquake parameters and subsurface properties, yielding true joint probabilities that an event occurs in a certain location, and above a certain magnitude. We will apply the method to several existing datasets. One contains the magnitude 2.3 event at Preese Hall, Lancashire, which halted the testing of hydraulic fracturing in May 2011, and so is a direct recording of what might be expected in future. Another is a set of mining-induced events which were recorded at the New Ollerton coal mine in Nottinghamshire, and serves as an excellent analogue for future industrial deployments in the UK. We will also test our ability to image magma chambers beneath three volcanoes, in Bolivia and Ethiopia, using our method applied to available data. By comparing our results to those from existing methods, we will show where bias is present in traditional techniques. Our method, having been validated in several ways, will serve as a useful ground truth against which we may compare methods which do not fully account for the linked distribution of subsurface velocities and event magnitude. The overarching objective of this proposal is to develop a new method to better image the Earth and enable the creating of specific, testable hypotheses of Earth processes and structure. However, a paired, integral objective is to devise new recommendations to improve monitoring and high-value decision-making for the future of induced seismicity in the UK and worldwide. We will use the results of the work packages we describe to construct specific, probabilistic thresholds for future 'traffic light' monitoring systems, and benefit regulators, operators and the public.

Submarine landslides can be far larger than terrestrial landslides, and many generate destructive tsunamis. The Storegga Slide offshore Norway covers an area larger than Scotland and contains enough sediment to cover all of Scotland to a depth of 80 m. This huge slide occurred 8,200 years ago and extends for 800 km down slope. It produced a tsunami with a run up >20 m around the Norwegian Sea and 3-8 m on the Scottish mainland. The UK faces few other natural hazards that could cause damage on the scale of a repeat of the Storegga Slide tsunami. The Storegga Slide is not the only huge submarine slide in the Norwegian Sea. Published data suggest that there have been at least six such slides in the last 20,000 years. For instance, the Traenadjupet Slide occurred 4,000 years ago and involved ~900 km3 of sediment. Based on a recurrence interval of 4,000 years (2 events in the last 8,000 years, or 6 events in 20,000 years), there is a 5% probability of a major submarine slide, and possible tsunami, occurring in the next 200 years. Sedimentary deposits in Shetland dated at 1500 and 5500 years, in addition to the 8200 year Storegga deposit, are thought to indicate tsunami impacts and provide evidence that the Arctic tsunami hazard is still poorly understood. Given the potential impact of tsunamis generated by Arctic landslides, we need a rigorous assessment of the hazard they pose to the UK over the next 100-200 years, their potential cost to society, degree to which existing sea defences protect the UK, and how tsunami hazards could be incorporated into multi-hazard flood risk management. This project is timely because rapid climatic change in the Arctic could increase the risk posed by landslide-tsunamis. Crustal rebound associated with future ice melting may produce larger and more frequent earthquakes, such as probably triggered the Storegga Slide 8200 years ago. The Arctic is also predicted to undergo particularly rapid warming in the next few decades that could lead to dissociation of gas hydrates (ice-like compounds of methane and water) in marine sediments, weakening the sediment and potentially increasing the landsliding risk. Our objectives will be achieved through an integrated series of work blocks that examine the frequency of landslides in the Norwegian Sea preserved in the recent geological record, associated tsunami deposits in Shetland, future trends in frequency and size of earthquakes due to ice melting, slope stability and tsunami generation by landslides, tsunami inundation of the UK and potential societal costs. This forms a work flow that starts with observations of past landslides and evolves through modelling of their consequences to predicting and costing the consequences of potential future landslides and associated tsunamis. Particular attention will be paid to societal impacts and mitigation strategies, including examination of the effectiveness of current sea defences. This will be achieved through engagement of stakeholders from the start of the project, including government agencies that manage UK flood risk, international bodies responsible for tsunami warning systems, and the re-insurance sector. The main deliverables will be: (i) better understanding of frequency of past Arctic landslides and resulting tsunami impact on the UK (ii) improved models for submarine landslides and associated tsunamis that help to understand why certain landslides cause tsunamis, and others don't. (iii) a single modelling strategy that starts with a coupled landslide-tsunami source, tracks propagation of the tsunami across the Norwegian Sea, and ends with inundation of the UK coast. Tsunami sources of various sizes and origins will be tested (iv) a detailed evaluation of the consequences and societal cost to the UK of tsunami flooding , including the effectiveness of existing flood defences (v) an assessment of how climate change may alter landslide frequency and thus tsunami risk to the UK.

On 24/08/2016, 01:36:33 UTC an earthquake of magnitude M=6.2 occurred at Norcia, Italy, killing more than 290 people, injuring 500 more, and leaving some 2,500 local inhabitants without a home. The earthquake resulted from movement on a normal fault in the Apennines mountain chain that runs along the Italian peninsula. Large destructive earthquakes of similar rupture style have occurred throughout this region in the past, most recently the 2009 M=6.4 L'Aquila event, 43 km S of the recent epicenter. Immediately after the Norcia earthquake, a UK scientific team led by the British Geological Survey, together with the University of Edinburgh, coordinated with the Instituto Nationale Geophysica e Vulcanologia (INGV) to enable the deployment of a high -density temporary seismic network to study the aftershock sequence. To date, 26 UK seismic recording stations are fully integrated with the INGV network and this will enable a high-accuracy updated earthquake catalogue to be derived with a greater regional coverage and improved magnitude sensitivity. The dataset collected within the next 6 months will be the basis of the development of aftershock forecast models and their transparent testing following international protocols. Aftershock forecasts are based on our understanding of earthquake triggering mechanisms and the empirical knowledge from previous aftershock sequence in the broader region. A validation of our forecasts using widely accepted statistical metrics is necessary in order to determine the strengths and weaknesses behind our triggering hypothesis and ensure that new knowledge will be passed on to improve operational aftershock forecasting world-wide.

Starting with the great Sumatra-Andaman earthquake M=9.2 of 26 December 2004 over 2000km of the Sunda megathrust, where the Indian ocean plate is being forced under the Asian plate, has been ruptured in a series of great M>8 earthquakes. The most recent, of magnitude 8.4, occurred on 12 September 2007. Of the more than 2500km of the megathrust, from the Andaman Islands to Enganno, only 300km remains un-ruptured in the last three years. This segment, under the Island of Siberut is still capable of an earthquake of greater than magnitude 8. It has not failed since 1797, from examination of the way the earth's crust is being deformed in the area we know that it has not experienced any slow (aseismic) slip. Simple calculations, using the known rate of convergence of the plates here, show that all the strain released in 1797 has been regained and it seems clear that it is ripe for another earthquake. This could happen at any time. In addition, it is clear from earlier work and from preliminary investigation of the recent events, that the segment under Siberut is now being stressed from the north by the 2005 event and from the south by the 12/09/07 event. It is likely that such an earthquake might cause a tsunami. The maximum height of Padang, broadside on to the Siberut segment, is only 10m above sea level so a tsunami is a real threat. However, it does not have to be as destructive as the 2004 tsunami. Indeed recent work we have done, funded by NERC in 2006, has shown that the presence of the Islands offshore Padang make the threat of a massive tsunami recede significantly. Our forecasts of smaller waves generated by western Sumatran megathrust earthquakes would appear to have been borne out by preliminary data from tsunami generated by the recent M8.4 earthquake which only reached 4m in height and apparently killed no one. Recently, we have made predictions relating the height of a tsunami observed on the Sumatran Coast to the vertical movement experienced there. When one of these earthquakes occurs the offshore islands are forced upward by the earthquake while the coast of Sumatra always drops / sometimes by metres. By a detailed series of coupled earthquake and tsunami simulations we have shown that the wave height experienced onshore is directly proportional to the size of this drop. The beauty is that the size of the vertical movement can be measured up to 30 minutes before the wave arrives. The recent earthquake should allow us to test this relationship. In this project we aim to do three things. Firstly, we plan to reassess the stresses under the island of Siberut accounting for the entire earthquake sequence. These calculations, particularly the time varying components, are complex and require sophisticated computations which we will finalise during the project. Secondly, we will test the predictions of our tsunami simulation methods against data collected by the recent M8.4 event and investigate the relationship between wave height and vertical displacement. This will involve a 2 week field campaign to collect information about the wave heights near the city of Bengkulu which was hit by the recent tsunami. Scars left by the tsunami will still be clearly visible for the next couple of months and can be measured accurately in the field. Using high resolution GPS equipment, which we will borrow from the NERC Geophysical Equipment Facility, we will accurately locate the positions of wave height estimates and also measure the present height of the coast. These heights will allow us to estimate the change in height during the earthquake. Finally, we will compute another suite of tsunami scenarios taking into account the recent earthquakes and the results of our validation work. Western Sumatra is currently one of highest earthquake risk areas in the world. This project will not stop the earthquake but it will contribute to a body of scientific knowledge which will help to prepare people for it.

Submarine landslides can be far larger than terrestrial landslides, and many generate destructive tsunamis. The Storegga Slide offshore Norway covers an area larger than Scotland and contains enough sediment to cover all of Scotland to a depth of 80 m. This huge slide occurred 8,200 years ago and extends for 800 km down slope. It produced a tsunami with a run up >20 m around the Norwegian Sea and 3-8 m on the Scottish mainland. The UK faces few other natural hazards that could cause damage on the scale of a repeat of the Storegga Slide tsunami. The Storegga Slide is not the only huge submarine slide in the Norwegian Sea. Published data suggest that there have been at least six such slides in the last 20,000 years. For instance, the Traenadjupet Slide occurred 4,000 years ago and involved ~900 km3 of sediment. Based on a recurrence interval of 4,000 years (2 events in the last 8,000 years, or 6 events in 20,000 years), there is a 5% probability of a major submarine slide, and possible tsunami, occurring in the next 200 years. Sedimentary deposits in Shetland dated at 1500 and 5500 years, in addition to the 8200 year Storegga deposit, are thought to indicate tsunami impacts and provide evidence that the Arctic tsunami hazard is still poorly understood. Given the potential impact of tsunamis generated by Arctic landslides, we need a rigorous assessment of the hazard they pose to the UK over the next 100-200 years, their potential cost to society, degree to which existing sea defences protect the UK, and how tsunami hazards could be incorporated into multi-hazard flood risk management. This project is timely because rapid climatic change in the Arctic could increase the risk posed by landslide-tsunamis. Crustal rebound associated with future ice melting may produce larger and more frequent earthquakes, such as probably triggered the Storegga Slide 8200 years ago. The Arctic is also predicted to undergo particularly rapid warming in the next few decades that could lead to dissociation of gas hydrates (ice-like compounds of methane and water) in marine sediments, weakening the sediment and potentially increasing the landsliding risk. Our objectives will be achieved through an integrated series of work blocks that examine the frequency of landslides in the Norwegian Sea preserved in the recent geological record, associated tsunami deposits in Shetland, future trends in frequency and size of earthquakes due to ice melting, slope stability and tsunami generation by landslides, tsunami inundation of the UK and potential societal costs. This forms a work flow that starts with observations of past landslides and evolves through modelling of their consequences to predicting and costing the consequences of potential future landslides and associated tsunamis. Particular attention will be paid to societal impacts and mitigation strategies, including examination of the effectiveness of current sea defences. This will be achieved through engagement of stakeholders from the start of the project, including government agencies that manage UK flood risk, international bodies responsible for tsunami warning systems, and the re-insurance sector. The main deliverables will be: (i) better understanding of frequency of past Arctic landslides and resulting tsunami impact on the UK (ii) improved models for submarine landslides and associated tsunamis that help to understand why certain landslides cause tsunamis, and others don't. (iii) a single modelling strategy that starts with a coupled landslide-tsunami source, tracks propagation of the tsunami across the Norwegian Sea, and ends with inundation of the UK coast. Tsunami sources of various sizes and origins will be tested (iv) a detailed evaluation of the consequences and societal cost to the UK of tsunami flooding , including the effectiveness of existing flood defences (v) an assessment of how climate change may alter landslide frequency and thus tsunami risk to the UK.