Columnar structures have been exposed by preferential weathering in non-welded, non-vapor-phase-altered zones of the 1.2 to 1.8 Ma Bandelier Tuff ignimbrites around Valles Caldera, New Mexico. These long, largely vertical cylindrical features are similar in composition and texture to the host ignimbrite but represent areas that underwent alteration to make them more resistant to erosion. Analyses show that the column ignimbrite was altered by the addition of the zeolite mordenite as a mineral cement into pore spaces. This, and the presence of illite and, to a lesser extent, chlorite, suggests alteration at similar to 120-125 degrees C. We map column geometry, spacing, stratigraphic location, and spatial distribution. Columns are mostly vertical, there is a correlation between the diameters and spacing, and they exist in linear to rounded clusters of a few to 30 columns. Based on the location within the ignimbrites, the shape and form of column groups, and the temperature of formation of the columns, we propose that slumping of over-steepened valley walls exposed friable, warm, unaltered ignimbrite that enabled ponded meteoritic water to permeate into the deposit, which allowed localized convective chimney cells to form. We develop an analytical model to show that infiltrating water is convectively unstable, and, for reasonable permeabilities, we can explain the observed column spacing and alteration temperature. This model permits columns to form within parts of the deposits perched in ignimbrite deposited against pre-existing valley walls. An abundant supply of water from high precipitation is implied, reflecting a syn-glacial, pluvial climate in the southwestern United States at that time (1-2 Ma ago).

Observations of terrestrial analogs are critical to aiding planetary mappers in interpreting surface lithologies on other planets. For instance, the presence of ignimbrites on Mars has been debated for over three decades and is supported by analogy with deposits on Earth. Critical evidence includes the geomorphic and surface expression of the deposits, and those in the Central Andes of South America are amongst the most-cited analogs. Herein we describe some prominent surface textures and patterns seen in ignimbrites on the scale of high-resolution remotely sensed data (10-1 m per pixel). These include pervasive joints and fractures that contribute to yardang form and development as well as prominent mounds, fissures, and fracture networks ("spiders", "bugs", "boxworks") on ignimbrite surfaces. While all these features are related to intrinsic cooling and degassing processes, the involvement of external water buried by hot pyroclastic flows enhances fumarolic activity, advective cooling, and joint development. Observations of these geomorphic expressions using remote sensing are only possible with the highest resolution data and limited surface erosion. For Mars, where similarly high resolution datasets are available (for example, the High Resolution Imaging Sensor Experiment or HiRISE) extensive dust cover may limit the recognition of similar features there. However significant relief on some of these features on Earth indicate they might still be detectable on Mars. (C) 2017 Elsevier B.V. All rights reserved.

Google Earth tours (GETs) are recorded flights around Google Earth. They are highly engaging to watch and have great potential for communicating spatially in a teaching environment. They also benefit from being easy for an educator to produce but they can be ineffective if they are designed poorly. With this in mind, in this paper we cover three main topics: (1) we consider how best to produce GETs, (2) we deconstruct them as a communication media and finally (3), we consider the larger educational context in which they are used. By reviewing literature relevant to these areas we produce 19 best practices for using GETs in education. The amount of evidence we can show in support of our best practices varies. Those that were generated by comparing GETs to the well-researched area of educational animations are highly reliable because they are based on empirical evidence. Those associated with the virtual flights between locations within a GET are more open to interpretation as they have been less well studied. We conclude that further work should be focused on investigating virtual flight within a GET.

Volcanoes often erupt explosively and generate a variety of hazards including volcanic ash clouds and gaseous plumes. These clouds and plumes are a significant hazard to the aviation industry and the ground features can be a major hazard to local communities. Here, we provide a chronology of the 2009 Redoubt Volcano eruption using frequent, low spatial resolution thermal infrared (TIR), mid-infrared (MIR) and ultraviolet (UV) satellite remote sensing data. The first explosion of the 2009 eruption of Redoubt Volcano occurred on March 15, 2009 (UTC) and was followed by a series of magmatic explosive events starting on March 23 (UTC). From March 23–April 4 2009, satellites imaged at least 19 separate explosive events that sent ash clouds up to 18km above sea level (ASL) that dispersed ash across the Cook Inlet region. In this manuscript, we provide an overview of the ash clouds and plumes from the 19 explosive events, detailing their cloud-top heights and discussing the variations in infrared absorption signals. We show that the timing of the TIR data relative to the event end time was critical for inferring the TIR derived height and true cloud top height. The ash clouds were high in water content, likely in the form of ice, which masked the negative TIR brightness temperature difference (BTD) signal typically used for volcanic ash detection. The analysis shown here illustrates the utility of remote sensing data during volcanic crises to measure critical real-time parameters, such as cloud-top heights, changes in ground-based thermal activity, and plume/cloud location.

Keyhole Markup Language (KML)—a type of extensible markup language (XML)—is the key to the extensibility of Google Earth for geoscience applications. Static KML code may be saved to a file from the Google Earth desktop application, handwritten with a text editor, or generated by running a custom computer program. Many Google Earth visualizations are limited to static KML developed with the desktop application's user interface. The purpose of this paper is to highlight how much more is possible with the implementation of additional applications. Geoscience learning resources may be taken to the next level with the interactive generation and animation of graphics and models both in the desktop application and using the Google Earth web browser plug-in and its JavaScript application programing interface. Dynamic KML may be generated on-the-fly by means of client-side or server-side scripts, or with the aid of Google Fusion Tables and network links.

The 3D reproduction of dam-break floods plays a key role in emergency management and disaster information dissemination. However, existing systems for the simulation of floods have some deficiencies. First, the input data parameters are complex. Second, the simulation process is cumbersome and time consuming, and it lacks a complete workflow. In this paper, we develop a platform for the rapid 3D reproduction of dam-break floods. Key technologies, such as numerical models of dam-break floods based on cellular automata (CA), 3D reproduction constrained by post-disaster information, and dynamic augmented representation, are discussed in detail. Then, two typical dam-break flood cases are selected for experimental analysis. The experimental results show that the system can support the rapid 3D reproduction of dam-break floods constrained by post-disaster information. Compared with that of other simulation systems, the reproduction time is reduced to less than 1 h, and this system supports rapid reproduction at different times and positions.

Volcanic ash is one of the major potential hazards from volcanic eruptions. It can have both short-range effects from proximal ashfall and long range impacts from volcanic ash clouds. The timely tracking and understanding of recently emitted volcanic ash clouds is important, because they can cause severe damage to jet aircraft engines and shut down major airports. Dispersion models play an important role in forecasting the movement of volcanic ash clouds by being the only means to predict a clouds' trajectory. Where available, comparisons are possible to both remote-sensing data and observations from the ground and aircraft. This was demonstrated in January 2006, when Augustine Volcano erupted after about a 20-year hiatus. From January 11 to 28, 2006, there were 13 explosive events, with some lasting as long as 11 minutes and producing ash clouds as high as 10-12 km (33,000-39,000 ft) above mean sea level (a.m.s.l). From January 28 to February 4, 2006, there was a more continuous phase, with ash clouds reaching 4-5 km a.m.s.l (13,000-16,000 ft). During the eruption, the Puff dispersion model was used by the Alaska Volcano Observatory for trajectory forecasting of the associated volcanic ash eruption clouds. The six explosive events on January 13 and 14, 2006, were the first time the 'multiple eruptions' capability of the Puff model was used during an eruption response. Here we show the Puff model predictions made during the 2006 Augustine eruption and compare these predictions to satellite remote-sensing data, Next Generation Radar (NEXRAD) radar, and ashfall measurements. In addition, we discuss how automated predictions for volcanoes at elevated alert status provide a quicker assessment of the risk from the potential ash clouds.

Satellite observations played an important role in monitoring the 2006 eruption of Augustine Volcano. It represented the first opportunity for observers to use, in an operational setting, new Web-based tools and techniques developed by the Alaska Volcano Observatory remote sensing group. The 'Okmok Algorithm' was used to analyze thermal infrared satellite data and highlight changes in the style and phases of activity. Temperature measurements were used to estimate ash cloud heights, which compared favorably to radar and ground-based observations, although larger discrepancies were seen when compared to pilot reports. Brightness temperature difference techniques were used to locate and track the 14 ash clouds produced during the explosive phase of the eruption. Stacking of these analyses allowed the creation of composite maps showing the distribution of airborne ash. The data from these maps were further combined with information from local reports and samples of ashfall to create a prototype of a concentration map that could be used to assess the potential hazard an eruption represents to aircraft, infrastructure and human health.

There are over 100 active volcanoes in the North Pacific (NOPAC) region, most of which are located in sparsely populated areas. Dispersion models play an important role in forecasting the movement of volcanic ash clouds by complementing both remote sensing data and visual observations from the ground and aircraft. Puff is a three-dimensional dispersion model, primarily designed for forecasting volcanic ash dispersion, used by the Alaska Volcano Observatory and other agencies. Since early 2007, the model is in an automated mode to predict the movement of airborne volcanic ash at multiple elevated alert status volcanoes worldwide to provide immediate information when an eruption occurs. Twelve of the predictions are within the NOPAC region, nine more within the southern section of the Pacific ring of fire and the others are in Europe and the Caribbean. Model forecasts are made for initial ash plumes ranging from 4 to 20 km altitude above sea level and for a 24-h forecast period. This information is made available via the Puff model website. Model results can be displayed in Virtual Globes for three-dimensional visualization. Here, we show operational Puff predictions in two and three-dimensions in Google Earth®, both as iso-surfaces and particles, and study past eruptions to illustrate the capabilities that the Virtual Globes can provide. In addition, we show the opportunity that Google Maps® provides in displaying Puff operational predictions via an application programming web interface and how radiosonde data (vertical soundings) and numerical weather prediction vertical profiles can be displayed in Virtual Globes for assisting in estimating ash cloud heights.

Volcanic eruptions produce ash clouds, which are a major hazard to population centers and the aviation community. Within the North Pacific (NOPAC) region, there have been numerous volcanic ash clouds that have reached aviation routes. Others have closed airports and traveled for thousands of kilometers. Being able to detect these ash clouds and then provide an assessment of their potential movement is essential for hazard assessment and mitigation. Remote sensing satellite data, through the reverse absorption or split window method, is used to detect these volcanic ash clouds, with a negative signal produced from spectrally semi-transparent ash clouds. Single channel satellite is used to detect the early eruption spectrally opaque ash clouds. Volcanic Ash Transport and Dispersion (VATD) models are used to provide a forecast of the ash clouds' future location. The Alaska Volcano Observatory (AVO) remote sensing ash detection system automatically analyzes satellite data of volcanic ash clouds, detecting new ash clouds and also providing alerts, both email and text, to those with AVO. However, there are also non-volcanic related features across the NOPAC region that can produce a negative signal. These can complicate alerts and warning of impending ash clouds. Discussions and examples are shown of these non-volcanic features and some analysis is provided on how these features can be discriminated from volcanic ash clouds. Finally, there is discussion on how information of the ash cloud such as location, particle size and concentrations, could be used as VATD model initialization. These model forecasts could then provide an improved assessment of the clouds' future movement.

The conditions of formation and the form of yardangs in ignimbrites in the Central Andes of Chile, Bolivia, and Argentina may be the most convincing terrestrial analog to the processes and lithology that produce the extensive yardangs of the Medusae Fossae Formation (MFF) of Mars. Through remote and field study of yardang morphologies in the Central Andes we highlight the role that variable material properties of the host lithology plays in their final form. Here, ignimbrites typically show two main facies: an indurated and jointed facies, and a weakly to poorly indurated, ash- and pumice-rich facies. Both facies are vertically arranged in large (erupted volume >100's of km3) ignimbrites resulting in a resistant capping layer, while smaller (10's of km3) ignimbrites are made predominantly of the weakly indurated facies. The two facies have quite different mechanical properties; the indurated facies behaves as strong rock, fails by block collapse and supports steep/vertical cliffs, while the non-indurated facies is more easily eroded and forms gentle slopes and manifests as more subdued erosional forms. In response to aeolian action, the presence of an upper indurated facies results in large, elongate, high aspect ratio (1:20–1:40) megayardangs that form tall (100m), thin ridges with steep to vertical walls. These are built on a broad apron of the weakly indurated facies with abundant fallen blocks from the upper indurated facies. These terrestrial megayardangs appear to be analogous to megayardangs with associated block fields seen on Mars. Smaller-volume, weakly indurated ignimbrites are sculpted into smaller, stubbier forms with aspect ratios of 1:5–1:10 and heights rarely exceeding 10m. Excavation of a windward basal moat suggests an erosional progression like that seen in incipient yardangs on Mars. Excavation rates of 0.007–0.003cm/year are calculated for the weakly indurated ignimbrites. While a persistent strong unidirectional wind is the dominant parameter controlling yardang formation and orientation, a role for flow separation and vorticity is also suggested by our observations at both yardang types. While the indurated facies is commonly pervasively jointed, jointing is of secondary importance in controlling yardang orientation. Serrated margins, a common feature on Mars, result from oblique intersections of jointing with yardang flanks or scarps of ignimbrite. The processes of yardang formation we describe from ignimbrites from the Central Andes are not necessarily specific to ignimbrites, but do connote that degree and distribution of induration is a major control in yardang formation and this has implications for the lithology of the MFF on Mars.