Abstract Waveform tomography with very large datasets reveals the upper-mantle structure of the Arctic in unprecedented detail. Using tomography jointly with computational petrology, we estimate temperature in the lithosphere–asthenosphere depth range and infer lithospheric structure and evolution. Most of the boundaries of the mantle roots of cratons in the Arctic are coincident with their geological boundaries at the surface. The thick lithospheres of the Greenland and North American cratons are separated by a corridor of thin lithosphere beneath Baffin Bay and through the middle of the Canadian Arctic Archipelago; the southern archipelago is part of the North American Craton. The mantle root of the cratonic block beneath northern Greenland may extend westwards as far as central Ellesmere Island. The Barents and Kara seas show high velocities indicative of thick lithosphere, similar to cratons. The locations of intraplate basaltic volcanism attributed to the High Arctic Large Igneous Province are all on thin, non-cratonic lithosphere. The lithosphere beneath the central part of the Siberian Traps is warmer than elsewhere beneath the Siberian Craton. This observation is consistent with lithospheric erosion associated with the large igneous province volcanism. A corridor of relatively low seismic velocities cuts east–west across central Greenland. This indicates lithospheric thinning, which appears to delineate the track of the Iceland hotspot. Supplementary material: Figures with comparisons of different tomographic models at 50 and 200 km depths are available at https://doi.org/10.6084/m9.figshare.c.3817810

Abstract The HOTSAT multiplatform system for the analysis of infrared data from satellites provides a framework that allows the detection of volcanic hotspots and an output of their associated radiative power. This multiplatform system can operate on both Moderate Resolution Imaging Spectroradiometer and Spinning Enhanced Visible and Infrared Imager data. The new version of the system is now implemented on graphics processing units and its interface is available on the internet under restricted access conditions. Combining the estimation of time-varying discharge rates using HOTSAT with the MAGFLOW physics-based model to simulate lava flow paths resulted in the first operational system in which satellite observations drive the modelling of lava flow emplacement. This allows the timely definition of the parameters and maps essential for hazard assessment, including the propagation time of lava flows and the maximum run-out distance. The system was first used in an operational context during the paroxysmal episode at Mt Etna on 12–13 January 2011, when we produced real-time predictions of the areas likely to be inundated by lava flows while the eruption was still ongoing. This allowed key at-risk areas to be rapidly and appropriately identified.

Abstract Lava ingress into a vulnerable population will be difficult to control, so that evacuation will be necessary for communities in the path of the active lava, followed by post-event population, infrastructural, societal and community replacement and/or relocation. There is a pressing need to set up a response chain that bridges scientists and responders during an effusive crisis to allow near-real-time delivery of globally standard ‘products’ for a timely and adequate humanitarian response. In this chain, the scientific research groups investigating lava remote-sensing and modelling need to provide products that are both useful to, and trusted by, the crisis response community. Requirements for these products include (a) formats that can be immediately integrated into a crisis management procedure, and (b) in an agreed and stable standard. A review of current capability reveals that we are at a point where the community can provide such a response, as is the aim of the RED SEED (Risk Evaluation, Detection and Simulation during Effusive Eruption Disasters) working group. This book is the first production of this group and is intended not only as a directory of current capabilities and operational service providers, but also as a statement of intent and need, while providing a simulation designed to demonstrate how a truly pan-disciplinary response to an effusive crisis could work.

Abstract Infrared (IR) satellite-based sensors allow the detection and quantification of volcanic hot spots. Sensors flown on geostationary satellites are particularly helpful in the early warning and continuous tracking of effusive activity. Development of operational monitoring and dissemination systems is essential to achieve the real-time ingestion and processing of IR data for a timely response during volcanic crises. HOTVOLC is a web-based satellite-data-driven monitoring system developed at the Observatoire de Physique du Globe de Clermont-Ferrand (Clermont-Ferrand), designed to achieve near-real-time monitoring of volcanic activity using on-site ingestion of geostationary satellite data (e.g. MSG-SEVIRI, MTSAT, GOES-Imager). Here we present the characteristics of the HOTVOLC system for the monitoring of effusive activity. The system comprises two acquisition stations and secure databases (i.e. mirrored archives). The detection of volcanic hot spots uses a contextual algorithm that is based on a modified form of the Normalized Thermal Index (NTI*) and VAST. Raster images and numerical data are available to open-access on a Web-GIS interface. Tests are carried out and presented here, particularly for the 12–13 January 2011 eruption of Mount Etna, to show the capability of the system to provide quantitative information such as lava volume and time-averaged discharge rate. Examples of operational application reveal the ability of the HOTVOLC system to provide timely thermal information about volcanic hot spot activity.

Abstract Using the NEODAAS-Dundee AVHRR receiving station (Scotland), NEODAAS-Plymouth can provide calibrated brightness temperature data to end users or interim users in near-real time. Between 2000 and 2009 these data were used to undertake volcano hot spot detection, reporting and time-average discharge rate dissemination during effusive crises at Mount Etna and Stromboli (Italy). Data were passed via FTP, within an hour of image generation, to the hot spot detection system maintained at Hawaii Institute of Geophysics and Planetology (HIGP, University of Hawaii at Manoa, Honolulu, USA). Final product generation and quality control were completed manually at HIGP once a day, so as to provide information to onsite monitoring agencies for their incorporation into daily reporting duties to Italian Civil Protection. We here describe the processing and dissemination chain, which was designed so as to provide timely, useable, quality-controlled and relevant information for ‘one voice’ reporting by the responsible monitoring agencies.

Abstract RED SEED stands for Risk Evaluation, Detection and Simulation during Effusive Eruption Disasters, and combines stakeholders from the remote sensing, modelling and response communities with experience in tracking volcanic effusive events. The group first met during a three day-long workshop held in Clermont Ferrand (France) between 28 and 30 May 2013. During each day, presentations were given reviewing the state of the art in terms of (a) volcano hot spot detection and parameterization, (b) operational satellite-based hot spot detection systems, (c) lava flow modelling and (d) response protocols during effusive crises. At the end of each presentation set, the four groups retreated to discuss and report on requirements for a truly integrated and operational response that satisfactorily combines remote sensors, modellers and responders during an effusive crisis. The results of collating the final reports, and follow-up discussions that have been on-going since the workshop, are given here. We can reduce our discussions to four main findings. (1) Hot spot detection tools are operational and capable of providing effusive eruption onset notice within 15 min. (2) Spectral radiance metrics can also be provided with high degrees of confidence. However, if we are to achieve a truly global system, more local receiving stations need to be installed with hot spot detection and data processing modules running on-site and in real time. (3) Models are operational, but need real-time input of reliable time-averaged discharge rate data and regular updates of digital elevation models if they are to be effective; the latter can be provided by the radar/photogrammetry community. (4) Information needs to be provided in an agreed and standard format following an ensemble approach and using models that have been validated and recognized as trustworthy by the responding authorities. All of this requires a sophisticated and centralized data collection, distribution and reporting hub that is based on a philosophy of joint ownership and mutual trust. While the next chapter carries out an exercise to explore the viability of the last point, the detailed recommendations behind these findings are detailed here.

Abstract The observation of volcanic thermal activity from space dates back to the late 1960s. Several methods have been proposed to improve detection and monitoring capabilities of thermal volcanic features, and to characterize them to improve our understanding of volcanic processes, as well as to inform operational decisions. In this paper we review the RST VOLC algorithm, which has been designed and implemented for automated detection and near-real-time monitoring of volcanic hotspots. The algorithm is based on the general Robust Satellite Techniques (RST) approach, representing an original strategy for satellite data analysis in the space–time domain. It has proven to be a useful tool for investigating volcanoes worldwide, by means of different satellite sensors, onboard polar orbiting and geostationary platforms. The RST VOLC rationale, its requirements and main operational capabilities are described here, together with the advantages of the tool and the known limitations. Results achieved through the study of two past eruptive events are shown, together with some recent examples demonstrating the near-continuous monitoring capability offered by RST VOLC . A summary is also made of the type products that the method is able to generate and provide. Lastly, the future perspectives, in terms of its possible implementation on the new generation of satellite systems, are briefly discussed.

Abstract We describe a new volcanic hotspot detection system, named Middle InfraRed Observation of Volcanic Activity (MIROVA), based on the analysis of infrared data acquired by the Moderate Resolution Imaging Spectroradiometer sensor (MODIS). MIROVA uses the middle infrared radiation (MIR), measured by MODIS, in order to detect and measure the heat radiation deriving from volcanic activity. The algorithm combines spectral and spatial principles, allowing the detection of heat sources from 1 megawatt (MW) to more than 10 gigawatt (GW). This provides a unique opportunity to: (i) recognize small-scale variations in thermal output that may precede the onset of effusive activity; (ii) track the advance of large lava flows; (iii) estimate lava discharge rates; (iv) identify distinct effusive trends; and, lastly, (v) follow the cooling process of voluminous lava bodies for several months. Here we show the results obtained from data sets spanning 14 years recorded at the Stromboli and Mt Etna volcanoes, Italy, and we investigate the above aspects at these two persistently active volcanoes. Finally, we describe how the algorithm has been implemented within an operational near-real-time processing chain that enables the MIROVA system to provide data and infrared maps within 1–4 h of the satellite overpass.

Abstract The AVHotRR routine has been in operation since 2006 to process satellite data for monitoring active volcanoes in the Mediterranean area. Although originally developed to work with advanced very high-resolution radiometer (AVHRR) data, AVHotRR has been developed over the years to adapt to other sensors. In this work we present an improved version of the algorithm for hot-spot detection and effusion rate estimate. The underlying principles upon which the algorithm is based are discussed, focusing on the enhancements. The currently implemented version makes it possible to integrate results from different datasets in order to better constrain the detection of volcanic hot spots. In particular, the high temporal resolution of the SEVIRI instrument aboard MSG is key to reducing false positives in AVHRR and moderate resolution imaging spectroradiometer MODIS images. We propose here a new detection method based on the wavelet transform of SEVIRI data. Results from the application of AVHotRR to a dataset of AVHRR and SEVIRI images from Mt Etna, Italy, are presented and discussed with reference to the advantages and limitations of the algorithm.

Abstract Hawaiian volcanoes are highly accessible and well monitored by ground instruments. Nevertheless, observational gaps remain and thermal satellite imagery has proven useful in Hawai‘i for providing synoptic views of activity during intervals between field visits. Here we describe the beginning of a thermal remote sensing programme at the US Geological Survey Hawaiian Volcano Observatory (HVO). Whereas expensive receiving stations have been traditionally required to achieve rapid downloading of satellite data, we exploit free, low-latency data sources on the internet for timely access to GOES, MODIS, ASTER and EO-1 ALI imagery. Automated scripts at the observatory download these data and provide a basic display of the images. Satellite data have been extremely useful for monitoring the ongoing lava flow activity on Kīlauea’s East Rift Zone at Pu‘u ‘Ō‘ō over the past few years. A recent lava flow, named Kahauale‘a 2, was upslope from residential subdivisions for over a year. Satellite data helped track the slow advance of the flow and contributed to hazard assessments. Ongoing improvement to thermal remote sensing at HVO incorporates automated hotspot detection, effusion rate estimation and lava flow forecasting, as has been done in Italy. These improvements should be useful for monitoring future activity on Mauna Loa.

We present a comprehensive study of one of the key targets of the Sikhote-Alin orogen—Early Cretaceous rocks in the Kiselevka block of the Kiselevka-Manoma tectono-stratigraphic terrane. The characteristic component of natural remanent magnetization (NRM) for these rocks was isolated, and the fold test was positive (Dec = 275.8°, Inc = −33.8°, K = 33.3. α 95 = 8.0°). The paleolatitude along which rocks of the block were forming in the Early Cretaceous was defined by the direction of this component (paleolatitude 18°N ± 5°N) as well as coordinates of the paleomagnetic pole (Plat = 18.6°, Plong = 222.4°, with semi-axis of the ellipse of confidence limit dp = 5.2° and dm = 9.1° of the Kiselevka block. The geochemical composition of volcanic rocks in the block suggests that they formed in a within-plate oceanic environment like volcanic rocks of the Hawaii hotspot. Three paleoreconstructions were developed based on the newly received and published data, in accordance with which the Kiselevka block: (1) in the range of 135–105 Ma was moving on the Izanagi plate northwestward at a rate of 15–20 cm/yr up to the eastern edge of Eurasia, thus covering over 5000 km; and (2) in the range of 105–70 Ma was moving northward along the Eurasian transform margin within the accretionary complex fragment at a rate of 4–5 cm/yr to its current position (Lower Amur) as part of the Sikhote-Alin orogen.

Whether the volcanism of the Columbia River Plateau, eastern Snake River Plain, and Yellowstone (western U.S.) is related to a mantle plume or to plate tectonic processes is a long-standing controversy. There are many geological mismatches with the basic plume model as well as logical flaws, such as citing data postulated to require a deep-mantle origin in support of an “upper-mantle plume” model. USArray has recently yielded abundant new seismological results, but despite this, seismic analyses have still not resolved the disparity of opinion. This suggests that seismology may be unable to resolve the plume question for Yellowstone, and perhaps elsewhere. USArray data have inspired many new models that relate western U.S. volcanism to shallow mantle convection associated with subduction zone processes. Many of these models assume that the principal requirement for surface volcanism is melt in the mantle and that the lithosphere is essentially passive. In this paper we propose a pure plate model in which melt is commonplace in the mantle, and its inherent buoyancy is not what causes surface eruptions. Instead, it is extension of the lithosphere that permits melt to escape to the surface and eruptions to occur—the mere presence of underlying melt is not a sufficient condition. The time-progressive chain of rhyolitic calderas in the eastern Snake River Plain–Yellowstone zone that has formed since basin-range extension began at ca. 17 Ma results from laterally migrating lithospheric extension and thinning that has permitted basaltic magma to rise from the upper mantle and melt the lower crust. We propose that this migration formed part of the systematic eastward migration of the axis of most intense basin-range extension. The bimodal rhyolite-basalt volcanism followed migration of the locus of most rapid extension, not vice versa. This model does not depend on seismology to test it but instead on surface geological observations.

The few geological and geophysical studies of the Lyra Basin at the western margin of the Ontong Java Plateau (OJP; Pacific Ocean) revealed that it is underlain by thicker than normal oceanic crust. The unusually thick oceanic crust is attributed to the emplacement of massive lava flows from the OJP. Dredging was conducted to sample the inferred OJP crust on the Lyra Basin but instead recovered younger extrusives that may have covered the older plateau lavas in the area. The Lyra Basin extrusives are alkalic basalts with ( 87 Sr/ 86 Sr) t = 0.704513–0.705105, ( 143 Nd/ 144 Nd) t = 0.512709–0.512749, ε Nd (t) = +3.0 to +3.8, ( 206 Pb/ 204 Pb) t = 18.488–18.722, ( 207 Pb/ 204 Pb) t = 15.558–15.577, and ( 208 Pb/ 204 Pb) t = 38.467–38.680 that are distinct from those of the OJP tholeiites. They have age-corrected ( 187 Os/ 188 Os) t = 0.1263–0.1838 that overlap with the range of values determined for the Kroenke-type and Kwaimbaita-type OJP basalts, but their ( 176 Hf/ 177 Hf) t = 0.28295–0.28299 and ε Hf (t) = +7.9 to +9.3 values are lower. These isotopic compositions do not match those of any Polynesian ocean island volcanics. Instead, the Lyra Basin basalts have geochemical affinity and isotopic compositions that overlap with those of some alkalic suite and alnöites in the island of Malaita, Solomon Islands. Although not directly related to the main plateau volcanism at 120 Ma, the geochemical data and modeling suggest that the origin of the Lyra Basin alkalic rocks may be genetically linked to the mantle preserved in the OJP thick lithospheric root, with magmatic contribution from the Rarotongan hotspot.

The lack of field evidence for significant crustal stretching during the main phase of flood basalt eruption rules out a passive-mantle origin for the Columbia River Basalt Group. The short duration (1.1 m.y.) of the main-phase lavas, their large volume (~195,500 km 3 ), and their high eruption rate (~0.178 km 3 /yr) in an area of minimal extension (<<1%) are better explained by an active-mantle upwelling origin. Such a scenario could be satisfied by the arrival of a lower-mantle plume, or by the ascent of upper mantle through a slab gap or around the truncated edge of the Farallon plate. These competing ideas have been based on the interpretation of seismic data beneath the Yellowstone region that appear to resolve either a sheet of mantle upwelling extending downward into the mantle transition zone, or an irregular corridor of upwelling extending through the transition zone and into the lower mantle to ~900–1000 km depth. A lower-mantle origin is supported by the seismically resolved upward deflection in the ~660 km discontinuity at the base of the transition zone, which in turn is consistent with a lower-mantle chemical signature reflected in high 3 He/ 4 He ratios found in derivative basalts from both the Snake River Plain and the Columbia River flood basalt province. Mid-Miocene arrival of the Yellowstone plume was centered beneath the Oregon-Nevada border region, where there are direct spatial and temporal connections among the initiation of flood basalt volcanism at ca. 16.7 Ma, the initiation of rhyolitic volcanism at the western end of the Snake River Plain hotspot track at ca. 16.5 Ma, and the initiation of a major period of uplift and crustal extension in the northern Basin and Range between ca. 17 and 16 Ma. Rapid uplift and the propagation of volcanism away from this region are consistent with models of plume emplacement. The inability of seismic studies to image a mantle-plume fabric of radiating flow is due to its destruction by corner flow, which is evident in the contemporary east-west flow fabric derived from shear-wave splitting measurements.

The Miocene–Holocene East African Rift in Ethiopia is unique worldwide because it subaerially exposes the transition between continental rifting and seafloor spreading within a young continental flood basalt province. As such, it is an ideal study locale for continental breakup processes and hotspot tectonism. Here, we review the results of a recent multidisciplinary, multi-institutional effort to understand geological processes in the region: the Ethiopia Afar Geoscientific Lithospheric Experiment (EAGLE). In 2001–2003, dense broadband seismological networks probed the structure of the upper mantle, while controlled-source wide-angle profiles illuminated both along-axis and across-rift crustal structure of the Main Ethiopian Rift. These seismic experiments, complemented by gravity and magnetotelluric surveys, provide important constraints on variations in rift structure, deformation mechanisms, and melt distribution prior to breakup. Quaternary magmatic zones at the surface within the rift are underlain by high-velocity, dense gabbroic intrusions that accommodate extension without marked crustal thinning. A magnetotelluric study illuminated partial melt in the Ethiopian crust, consistent with an overarching hypothesis of magma-assisted rifting. Mantle tomographic images reveal an ~500-km-wide low-velocity zone at ≥75 km depth in the upper mantle that extends from close to the eastern edge of the Main Ethiopian Rift westward beneath the uplifted and flood basalt–capped NW Ethiopian Plateau. The low-velocity zone does not interact simply with the Miocene–Holocene (rifting-related) base of lithosphere topography, but it provides an abundant source of partially molten material that assists extension of the seismically and volcanically active Main Ethiopian Rift to the present day.

Alkaline magmatism along the Cameroon Line has been active for at least 67 m.y. and is currently defined by an almost SW-NE geological lineament (mean value: N30°E). Available petrological, geochemical, and structural data obtained over the last 20 yr lead us to reappraise its mechanism of emplacement. Known as the second most important geological curiosity in Africa, after the East African Rift system, it displays a continental part and an oceanic part, a unique feature in Africa and even in the world. The continental part contains both plutonic and volcanic massifs, and the oceanic part consists only of volcanic massifs. Plutonic rocks as a whole define a complete series of gabbro-diorite-monzonite-syenite-granite type, whereas volcanic rocks display abundant basic (basalt-hawaiite) and felsic (trachyte-phonolite-rhyolite) lavas with very few intermediate ones (mugearite-benmoreite). The formerly entire alkaline nature of these rocks is here ruled out by the discovery of volcanoes with geochemically transitional affinities in some areas of the continental sector. On the other hand, new K-Ar and 40 Ar/ 39 Ar dates confirm the absence of any age migration associated with the SW-NE linear trend. This lack of steady time-space migration and the SW-NE trend have also been observed in the magmatic provinces of Nigeria and Benue Trough, which share similar geochemical features with the Cameroon Line, and along the NE-SW major igneous lineaments in South Africa. The mechanism of such episodic emplacement of alkaline magmatism can be better explained in terms of complex interactions between hotspots and lithospheric fractures during African plate motion.

Post-Paleozoic magmatism in Angola and Namibia (SW Africa) is widespread along the continental margin (flood tholeiites of the Paraná-Etendeka system), and along transverse lineaments (alkaline and alkaline-carbonatitic complexes; sodic and potassic suites). These different magmatic suites are strictly associated in space and/or time. Variable melting degrees of a veined lithospheric mantle are proposed for the most “primitive” magmas from geochemical modeling and Sr-Nd isotope systematics. A complex evolution emerges for some ultramafic rocks (cumulus processes) and for differentiated rock compositions (assimilation and fractional crystallization, AFC, magma mixing), which may also involve anatexis of the crystalline basement and emplacement of S-type granites and rhyolites. Melting of a lithospheric mantle, without an appreciable contribution of the asthenosphere (thermal input excepted), is consistent with regional thermal anomalies in the deep mantle, mapped by gravity of the geoid, seismic tomography, and paleomagnetic analysis. The Walvis Ridge and Rio Grande “hotspot tracks” are interpreted as stress response in the lithosphere during rifting. A plume-related heat source is not favored by our results.

International field experiences offer exceptional opportunities for effective student learning in the geosciences. Over the 10 yr period between 1998 and 2008, more than 40 undergraduate students from 14 institutions participated in field research investigating active tectonics on the Nicoya Peninsula, Costa Rica. Three different project models were used: (1) a month-long summer research project, (2) a series of 1 to 2 wk independent field study projects, and (3) a week-long field research module. These projects shared a common research theme (active tectonics), field area (Nicoya Peninsula), and pedagogy (experiential learning), thus allowing for easy comparison of teaching methods, logistics, and learning outcomes. Each model has unique pedagogical benefits and challenges, and is therefore better suited for a different group size, student to faculty ratio, project duration, and budget. Collectively, these student research projects generated significant publishable data relevant to ongoing investigations of forearc tectonics and earthquake hazards along the Costa Rican Pacific margin. Individual student projects were carefully designed to provide a quality field learning experience, while adding a new piece to the larger research puzzle. Indicators of project success include levels of student engagement; gains in technical and cognitive field skills; and productivity of student-authored publications, reports, and presentations. Students commonly described these projects as instrumental in shaping their professional identity as geoscientists. Blending international field research with experiential learning pedagogy creates a powerful synergy that captures student imagination and motivates learning. By placing students beyond the comfort of their home learning environment, international field projects pique student curiosity, sharpen awareness and comprehension, and amplify the desire to learn. Experiential learning pedagogy encourages students to define their own research agenda and solve problems through critical thinking, inquiry, and reflection. The potent combination of international fieldwork and experiential learning helps students to develop the self-confidence and reasoning skills needed to solve multifaceted real-world problems, and provides exceptional training for graduate school and professional careers in the geosciences.

A conceptual shift is overdue in geodynamics. Popular models that present plate tectonics as being driven by bottom-heated whole-mantle convection, with or without plumes, are based on obsolete assumptions, are contradicted by much evidence, and fail to account for observed plate interactions. Subduction-hinge rollback is the key to viable mechanisms. The Pacific spreads rapidly yet shrinks by rollback, whereas the subduction-free Atlantic widens by slow mid-ocean spreading. These and other first-order features of global tectonics cannot be explained by conventional models. The behavior of arcs and the common presence of forearc basins on the uncrumpled thin leading edges of advancing arcs and continents are among features indicating that subduction provides the primary drive for both upper and lower plates. Subduction rights the density inversion that is produced when asthenosphere is cooled to oceanic lithosphere: plate tectonics is driven by top-down cooling but is enabled by heat. Slabs sink more steeply than they dip and, if old and dense, are plated down on the 660 km discontinuity. Broadside-sinking slabs push all sublithosphere oceanic upper mantle inward, forcing rapid spreading in shrinking oceans. Down-plated slabs are overpassed by advancing arcs and plates, and thus transferred to enlarging oceans and backarc basins. Plate motions make sense in terms of this subduction drive in a global framework in which the ridge-bounded Antarctic plate is fixed: most subduction hinges roll back in that frame, plates move toward subduction zones, and ridges migrate to tap fresh asthenosphere. This self-organizing kinematic system is driven from the top. Slabs probably do not subduct into, nor do plumes rise to the upper mantle from, the sluggish deep mantle.