This approach is currently being applied in a few cases, such as at Stromboli in Italy and Augustine in Alaska. Because every volcano is slightly different, we need predictive methodologies that apply not only to a specific volcano but to volcanoes generally. An urgent need is more widely deployed methods to monitor deep processes that may ultimately control eruptive activity (see Question 4). Such monitoring, using geodetic data primarily, has so far been applied at several volcanoes (e.g., Usu, Iwate, Miyakejima, Iwo Jima, Rabaul, Okmok, Westdahl, Akutan, South Sister, Etna, various Andean volcanoes), but there have been few chances to tie the observations to subsequent eruptions. This need applies especially to Mount St. Helens and Soufriere Hills volcano, in Montserrat, which have both been active for decades and are likely to erupt again relatively soon. Their eruptive activity requires successive inputs of magma from lower or midcrustal levels, a process that is still difficult to detect.

Summary

Thanks largely to better understanding of causes and sensitive new instrumentation, geologists have moved in recent decades toward predictive capabilities for volcanoes and, to a lesser extent, earthquakes. And yet the complexity of still-open theoretical questions and the growing human populations in threatened regions have both complicated their work and heightened its urgency.

Earth scientists have learned a great deal about predicting earthquake behavior. Plate tectonics provides a framework for understanding where most earthquakes occur and also constrains the long-term slip rate over complex fault systems. To predict the timing of individual earthquakes, however, we need to develop a deeper understanding of the factors that control the initiation and termination of fault rupture. New observational capabilities in seismology, geodesy, and geology continue to provide new insight into earthquake behavior, and new discoveries in the science of earthquakes continue apace. For ground motion prediction, high-performance computation holds forth the prospect of making physics-based simulations of earthquake strong ground motion. For all forms of earthquake prediction, it is important to find ways to validate new techniques as they are developed.

Studies of volcanic activity have also been propelled by technological developments, especially real-time seismic, electromagnetic, and geodetic probes of active subsurface processes. Improved understanding will require integrating these geophysical observations with field studies of volcanic structures and laboratory studies of volcanic materials. The ultimate objective is to develop a clear picture of magma movement: from its sources in the upper mantle to Earth’s crust, where it is temporarily stored, and ultimately to the surface where it erupts. Sensitive new geophysical and geochemical techniques are improving our ability to track magma movement, and field studies of uplifted, eroded magma reservoirs and feeder systems are providing clues about how to interpret this information. Improving the safety of growing populations in volcano-prone regions will require an increase in our fundamental understanding of volcanic eruptions and public education and better planning to decrease human vulnerability to volcanic eruptions.

QUESTION 10:
HOW DO FLUID FLOW AND TRANSPORT AFFECT THE HUMAN ENVIRONMENT?

Geological science has traditionally been closely tied to the assessment and discovery of natural resources such as minerals, petroleum, natural gas, geothermal water, and groundwater. More recently, geology has played a major part in understanding the fate of waste compounds and other materials released to the environment. In the future some of these waste products and byproducts, like carbon dioxide and radioactive elements from nuclear power plants, may be sequestered intentionally in geological formations. Geology is also concerned with the development of landscapes by erosion and tectonics, and increasingly this interest is focused on assessing the impacts of human activities on both the physical character of rivers and their drainage basins and the relationships between these physical characteristics, the risks of floods and landslides, and the health of ecosystems. Both of these categories of societal concern—resources and environmental impacts—are likely to increase in urgency in the future, and hence there is a continuing effort to improve access to underground resources, to maintain or manage existing resources both below ground and above ground, and



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