American Geophysical Union Fall Meeting

Executive Summary
The 2015 AGU Fall meeting was host to more than 15,000 scientific oral presentations and posters. To depart from past RPI conference write-ups on atmospheric hazards, this report summarises some of the more relevant and interesting contributions on geological, hydrological and space hazards. The main points from the talks are presented below, categorised by hazard type.

Tsunami Awareness of Atlantic Ocean tsunami sources and associated areas at risk is increasing. Several studies at AGU suggest that there is a significant tsunami risk in the Atlantic Basin, yet most work remains focussed on the Pacific and Indian Oceans. Evidence from a recent study by Ramalho et al. (2015) shows that a volcano sector collapse such as that which occurred on Fogo in the Cape Verde Islands ~73 ka could generate a megatsunami. A modern-day event of this magnitude would have devastating effects on nearby coastal populations. Lo Lacono et al. also highlighted the capacity for localised tsunami on the SW coast of Europe. Recognising that the 1531 Lisbon tsunami may have been generated by a submarine landslide has important implications for understanding geohazards in this region of the world. The discovery of potential tsunami deposits in Puget Sound, Washington by Carrie Garrison-Laney confirms that a fault rupture along the Cascadia Subduction Zone could have devastating effects on coastal towns and cities along the western coast of North America. This new paleo-tsunami evidence may be useful in constraining the historical amplitudes from previous Cascadia events, and continued research to identify the likely intensity and recurrence rates of Cascadia megathrust earthquakes would be beneficial to assess potential losses. Earthquakes have generated over 75% of all historically documented tsunamis. As a result, all existing tsunami warning and forecast systems focus almost exclusively on detecting, warning and forecasting earthquake-generated tsunamis. Whilst the probability of an asteroid impact remains low, existing tsunami forecast capabilities could (and should) be used to explore both hazard assessment and the forecast of a tsunami generated by the asteroid impact.

Induced Seismicity Over the past several years, the seismicity rate has increased significantly in multiple areas of the central U.S. These earthquakes are induced by human activities that change rapidly based on economic and policy decisions. Petersen et al. (2015) undertook work to include induced earthquakes identified in an additional 14 regions that were not included in the earthquake catalogue used for constructing the 2014 USGS seismic model. Results indicate that next year’s hazard is significantly higher by more than a factor of three in Oklahoma, Texas, and Colorado compared to the long-term 2014 hazard model, and represents an area of emerging risk that should be explored further.

Volcanic Ashfall Hazards Of all volcanic hazards, ashfall is the most likely to impact society because of the large areas affected. The widespread dispersal of ash can cause large-scale disruption of vital infrastructure services, aviation, and primary production. Recent effort has been made by the USGS to organize, distribute, and archive important information about volcanic ashfall impacts with a view towards developing improved emergency preparedness, response and recovery measures. Significant economic disruption to the aviation industry during the 2010 Eyjafjallajokull eruption in Iceland has led to improving the London VAAC’s volcanic ash monitoring, modelling and forecasting capabilities, and collaboration with research organisations, industry, other VAACs, Meteorological Services and the Volcano Observatory in Iceland.

California Drought California’s current drought has spanned four years and included many notable records for precipitation, snowpack, runoff, and temperature. Through an examination of various observed records, Andersen et al. provided prospective on the current drought as well as the 21st century so far with comparisons to past events including the paleo-record. Looking ahead using information ranging from seasonal forecasts to climate projections, thoughts were provided on the potential ramifications for California and what knowledge gaps inhibit adaptive planning and operational response. To explore the anthropogenic influence on the current drought conditions, Williams et al. presented an account of the natural and anthropogenic contributions to drought variability to date, and provided an in-depth evaluation of the recent extreme drought in California. The dramatic effects of the current drought in California, combined with knowledge that the background warming-driven drought trend will continue to intensify amidst a high degree of natural climate variability, highlight the critical need for a long-term outlook on drought resilience.

Flood Global flood risk models are being used more and more in practice, by an increasingly large number of practitioners and decision-makers. Flood risk estimates can help decision makers quantify and monetize flood damage in cost-benefit analyses when evaluating and financing risk mitigation and climate adaptation projects. However, global models are still fraught with limitations compared to local models. Whilst several global scale flood risk models have now been developed to assess both current and future river flood risk, to date none of these include currently installed or future flood risk management measures, nor their costs and benefits. Therein lie the areas of future work in global flood risk assessment.

Space Hazards Events produced by space weather include solar storms or geomagnetic disturbances. Geomagnetic disturbances can induce current through large electric power systems, putting them at risk of transformer failure and critical component damage. A relatively new area of risk, future research should focus on (1) scenario-based numerical modelling of geomagnetically induced currents on power systems to better understand the potential impacts and economic losses from future events, and (2) developing next generation GIC prediction products for the power industry.