A four-year study of shear-wave splitting in Iceland: 2. Temporal changes before earthquakes and volcanic eruptions
T. Volti, S. Crampin, 2003. "A four-year study of shear-wave splitting in Iceland: 2. Temporal changes before earthquakes and volcanic eruptions", New Insights into Structural Interpretation and Modelling, D. A. Nieuwland
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This chapter reports temporal variations in the time-delays between split shear-waves before both earthquakes and volcanic eruptions in Iceland. The hypothesis is that during a build-up of stress, crack distributions in a large volume surrounding the immediate source zone are modified until the level of cracking reaches fracture criticality, when shear strength is lost, rocks fracture, and earthquakes, or some types of eruptions occur. In one two-year period, when volcanic and magmatic activity appeared to be low, changes in shear-wave splitting in SW Iceland were observed routinely before earthquakes with magnitudes between M3.5 and M5.1. Assuming a linear relationship between earthquake magnitude and the rate of increasing crack aspect-ratio in this comparatively narrow amplitude range, the time and magnitude of a M5 earthquake was successfully stress-forecast. These results confirm a new understanding of pre-fracturing deformation of in situ rock that has implications over a wide range of situations where the crust undergoes changes at low levels of deformation below those at which rocks fracture. Potential applications of this new understanding include monitoring hydrocarbon production, as well as stress-forecasting earthquakes and some volcanic eruptions.
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New Insights into Structural Interpretation and Modelling
This title has arisen from the Geological Society of London conference of the same name. Since the publication of the predecessor of this book (‘Modern insights into structural interpretation, validation and modelling’, SP99, 1996, edited by Buchanan & Nieuwland) much progress has been made. This has been primarily thanks to the continuously increasing computing speed and computer memory capacity, which has positively affected all fields in structural interpretation, seismics and modelling, directly or indirectly.
‘New insights in structural interpretation and modelling’, presents a balanced overview of what the title promises. It is intended as a book that will serve the experienced professional as well as more advanced students in earth sciences, with a broad selection of topics ranging from classical field based studies to state of the art analogue and numerical modeling. The leaders of their fields have written some of the chapters, whereas younger authors with a fresh outlook and new ideas have written other chapters.