Marianne Guffanti

Thermal and mass implications of magmatic evolution in the Lassen volcanic region, California, and minimum constraints on basalt influx to the lower crust

We have analyzed the heat and mass demands of a petrologic model of basalt-driven magmatic evolution in which variously fractionated mafic magmas mix with silicic partial melts of the lower crust. We have formulated steady state heat budgets for two volcanically distinct areas in the Lassen region: the large, late Quaternary, intermediate to silicic Lassen volcanic center and the nearby, coeval, less evolved Caribou volcanic field. At Caribou volcanic field, heat provided by cooling and fractional crystallization of 52 km3 of basalt is more than sufficient to produce 10 km of rhyolitic melt by partial melting of lower crust. Net heat added by basalt intrusion at Caribou volcanic field is equivalent to an increase in lower crustal heat flow of ∼7 mW m−2, indicating that the field is not a major crustal thermal anomaly. Addition of cumulates from fractionation is offset by removal of erupted partial melts. A minimum basalt influx of 0.3 km3 (km2 Ma)−1 is needed to supply Caribou volcanic field. Our methodology does not fully account for an influx of basalt that remains in the crust as derivative intrusives. On the basis of comparison to deep heat flow, the input of basalt could be ∼3 to 7 times the amount we calculate. At Lassen volcanic center, at least 203 km3 of mantle-derived basalt is needed to produce 141 km3 of partial melt and drive the volcanic system. Partial melting mobilizes lower crustal material, augmenting the magmatic volume available for eruption at Lassen volcanic center; thus the erupted volume of 215 km3 exceeds the calculated basalt input of 203 km3. The minimum basalt input of 1.6 km3 (km2 Ma)−1 is >5 times the minimum influx to the Caribou volcanic field. Basalt influx high enough to sustain considerable partial melting, coupled with locally high extension rate, is a crucial factor in development of Lassen volcanic center; in contrast, Caribou volcanic field has failed to develop into a large silicic center primarily because basalt supply there has been insufficient.

Gravity anomalies, Quaternary vents, and Quaternary faults in the southern Cascade Range, Oregon and California: Implications for arc and backarc evolution

Isostatic residual gravity anomalies in the southern Cascade Range of northern California and southern Oregon are spatially correlated with broad zones of Quaternary magmatism as reflected by the total volume of Quaternary volcanic products, the distribution of Quaternary vents, and the anomalously low teleseismic P wave velocities in the upper 30 km of crust. The orientation of Quaternary faults also appears to be related to gravity anomalies and volcanism in this area, trending generally north-south within the magmatic regions and northwest-southeast as they enter the neighboring amagmatic zones to the north and south. The relationship between gravity anomalies, vent density, and fault orientations may indicate in a broad sense the strength of the middle and upper crust. The southern Cascade Range occupies a transition zone where horizontal stress is transferred from the northwest-southeast dextral shear of the Walker Lane belt to the east-west extension characteristic of the Cascade arc in central Oregon. Faulting along north-south strikes in the volcanically active areas indicates the east-west extensional stresses in thermally weakened crust, whereas northwest faulting between the volcanically active areas reflects the northwest trending, right lateral shear strain of the Walker Lane belt. The segmentation of the arc reflected in Quaternary magmatism may be caused by differential extension behind crustal blocks of the forearc rotating clockwise with respect to North America. In this view the volcanic centers at Mount Shasta, Medicine Lake volcano, and Lassen Peak in northern California are situated along the southern parts of the trailing edges of two distinct segments of the forearc where additional extension is implied by their differential clockwise rotation.

Volcanic Ash Hazards and Aviation Risk

The risks to safe and efficient air travel from volcanic-ash hazards are well documented and widely recognized. Under the aegis of the International Civil Aviation Organization, globally coordinated mitigation procedures are in place to report explosive eruptions, detect airborne ash clouds and forecast their expected movement, and issue specialized messages to warn aircraft away from hazardous airspace. This mitigation framework is based on the integration of scientific and technical capabilities worldwide in volcanology, meteorology, and atmospheric physics and chemistry. The 2010 eruption of Eyjafjallajokull volcano in Iceland, which led to a nearly week-long shutdown of air travel into and out of Europe, has prompted the aviation industry, regulators, and scientists to work more closely together to improve how hazardous airspace is defined and communicated. Volcanic ash will continue to threaten aviation and scientific research will continue to influence the risk-mitigation framework.

Volcanic Ash and Aviation—The Challenges of Real-Time, Global Communication of a Natural Hazard

More than 30 years after the first major aircraft encounters with volcanic ash over Indonesia in 1982, it remains challenging to inform aircraft in flight of the exact location of potentially dangerous ash clouds on their flight path, particularly shortly after the eruption has occurred. The difficulties include reliably forecasting and detecting the onset of significant explosive eruptions on a global basis, observing the dispersal of eruption clouds in real time, capturing their complex structure and constituents in atmospheric transport models, describing these observations and modelling results in a manner suitable for aviation users, delivering timely warning messages to the cockpit, flight planners and air traffic management systems, and the need for scientific development in order to undertake operational enhancements. The framework under which these issues are managed is the International Airways Volcano Watch (IAVW), administered by the International Civil Aviation Organization (ICAO). ICAO outlines in its standards and recommended practices (International Civil Aviation Organization 2014a, b) the basic volcanic monitoring and communication that is necessary at volcano observatories in Member States (countries). However, not all volcanoes are monitored and not all countries with volcanoes have mandated volcano observatories or equivalents. To add to the efforts of volcano observatories, a system of Meteorological Watch Offices, Air Traffic Management Area Control Centres, and nine specialist Volcanic Ash Advisory Centres (VAACs) are responsible for observing, analysing, forecasting and communicating the aviation hazard (airborne ash), using agreed techniques and messages in defined formats. Continuous improvement of the IAVW framework is overseen by expert groups representing the operators of the system, the user community, and the science community. The IAVW represents a unique marriage of two scientific disciplines, volcanology and meteorology, with the aviation user community. There have been many multifaceted volcanic eruptions in complex meteorological conditions during the history of the IAVW. Each new eruption brings new insights into how the warning system can be improved, and each reinforces the lessons that have gone before. The management of these events has improved greatly since the major ash encounters in the 1980s, but discontinuities in the warning and communications system still occur. A good example is a 2014 ash encounter over Indonesia following the eruption of Kelut where the warnings did not reach the aircraft crew. Other events present enormous management challenges—for example the 2010 Eyjafjallajokull eruption in Iceland was, overall, less hazardous than many less publicised eruptions, but numerous small to moderate explosions over several weeks produced widespread disruption and a large economic impact. At the time of writing, while there has been hundreds of millions of US dollars in damage to aircraft from encounters with ash, there have been no fatalities resulting from aviation incidents in, or proximal to volcanic ash cloud. This reflects, at least in part, the hard work done in putting together a global warning system—although to some extent it also reflects a measure of good statistical fortune. In order to minimise the risk of aircraft encounters with volcanic ash clouds, the global effort continues. The future priorities for the IAVW are strongly focused on enhancing communication before, and at the very onset of a volcanic ash-producing event (typically the more dangerous stage), together with improved downstream information and warning systems to help reduce the economic impact of eruptions on aviation.

A new organization to improve coordination of U.S. volcano monitoring

With nearly 70 active and potentially active volcanoes in five distinct tectonic settings, the United States is a volcanically vigorous country that repeatedly experiences significant levels of volcanic unrest and eruptive activity. Five interactive volcano observatories, supported mainly by the Volcano Hazards Program of the U.S. Geological Survey (USGS), conduct long-term monitoring and associated research investigations (see text box). In addition,through a joint program of USGS and the U.S. Agency for International Development, some volcanoes in other countries are visited—by invitation— by rapid-response teams of U.S. volcanologists who assist with monitoring and hazard assessment during periods of unrest or eruption. Monitoring operations at the volcano observatories are a cooperative undertaking, carried out using staff and facilities of USGS, and of partners at other federal and state agencies and at universities (These are partnerships that are formalized through Memoranda of Understanding, Congressional directive, or long-standing cooperative agreements with USGS.) The dispersed geographic and institutional nature of the observatory activities requires substantial interaction among all the scientific partners to achieve the desired level of cooperation.

Flying into Volcanic Ash Clouds: An Evaluation of Hazard Potential

Within the German Aerospace Center’s (DLR) internal project VolcATS (Volcanic ash impact on the Air Transport System), the DLR Institute of Flight Systems investigated the impact of volcanic ash on aircraft systems, especially on navigation and communication systems. In order to get a general overview of recent encounters of aircraft with volcanic ash clouds and possible damage to the aircraft, a compilation of known incidents from 2010 through 2016 was created in collaboration with the U.S. Geological Survey (USGS). Together with the DLR Institute of Flight Guidance, a more detailed analysis for selected incidents was performed by combining both flight trajectories and modeled volcanic ash concentration data. Finally, the database of known incidents from 1953-2009 published by USGS was merged with the new compilation in order to get a unique database of worldwide encounters of aircraft with volcanic ash clouds from 1953-2016.

Chapter 4 – Volcanic Ash Hazards and Aviation Risk

The risks to safe and efficient air travel from volcanic-ash hazards are well documented and widely recognized. Under the aegis of the International Civil Aviation Organization, globally coordinated mitigation procedures are in place to report explosive eruptions, detect airborne ash clouds and forecast their expected movement, and issue specialized messages to warn aircraft away from hazardous airspace. This mitigation framework is based on the integration of scientific and technical capabilities worldwide in volcanology, meteorology, and atmospheric physics and chemistry. The 2010 eruption of Eyjafjallajokull volcano in Iceland, which led to a nearly week-long shutdown of air travel into and out of Europe, has prompted the aviation industry, regulators, and scientists to work more closely together to improve how hazardous airspace is defined and communicated. Volcanic ash will continue to threaten aviation and scientific research will continue to influence the risk-mitigation framework.

Volcanic ash hazards and aviation risk: Chapter 4

The risks to safe and efficient air travel from volcanic-ash hazards are well documented and widely recognized. Under the aegis of the International Civil Aviation Organization, globally coordinated mitigation procedures are in place to report explosive eruptions, detect airborne ash clouds and forecast their expected movement, and issue specialized messages to warn aircraft away from hazardous airspace. This mitigation framework is based on the integration of scientific and technical capabilities worldwide in volcanology, meteorology, and atmospheric physics and chemistry. The 2010 eruption of Eyjafjallajokull volcano in Iceland, which led to a nearly week-long shutdown of air travel into and out of Europe, has prompted the aviation industry, regulators, and scientists to work more closely together to improve how hazardous airspace is defined and communicated. Volcanic ash will continue to threaten aviation and scientific research will continue to influence the risk-mitigation framework.

Real Time Volcanic Cloud Products and Predictions for Aviation Alerts

) and volcanic ash into the atmosphere, posing a substantial risk to aviation safety. Ingesting near-real time and Direct Readout satellite volcanic cloud data is vital for improving reliability of volcanic ash forecasts and mitigating the effects of volcanic eruptions on aviation and the economy. NASA volcanic products from the Ozone Monitoring Insrument (OMI) aboard the Aura satellite have been incorporated into Decision Support Systems of many operational agencies. With the Aura mission approaching its 10th anniversary, there is an urgent need to replace OMI data with those from the next generation operational NASA/NOAA Suomi National Polar Partnership (SNPP) satellite. The data provided from these instruments are being incorporated into forecasting models to provide quantitative ash forecasts for air traffic management. This study demonstrates the feasibility of the volcanic near-real time and Direct Readout data products from the new Ozone Monitoring and Profiling Suite (OMPS) ultraviolet sensor onboard SNPP for monitoring and forecasting volcanic clouds. The transition of NASA data production to our operational partners is outlined. Satellite observations are used to constrain volcanic cloud simulations and improve estimates of eruption parameters, resulting in more accurate forecasts. This is demonstrated for the 2012 eruption of Copahue. Volcanic eruptions are modeled using the Goddard Earth Observing System, Version 5 (GEOS-5) and the Goddard Chemistry Aerosol and Radiation Transport (GOCART) model. A hindcast of the disruptive eruption from Iceland’s Eyjafjallajokull is used to estimate aviation re-routing costs using Metron Aviation’s ATM Tools.