Urban Ecological Restoration: Setting Priorities for Restoring Native Vegetation in Lava Field Remnants in Mexico City

As cities overgrow, the need for ecological restoration is becoming increasingly urgent, especially in densely populated areas. Urban ecological restoration represents the best approach to undertake damages to restore native ecosystem remnants fulfilling biodiversity but also social goals in dense urban settings such as Mexico City. The feasibility of restoring unique xerophytic scrub vegetation in lava field remnants was evaluated in a portion of a university campus in Mexico City. Here we present an index (Need and Feasibility of Restoration Index, NFRI) for such purpose. The NFRI was designed through multicriteria analysis and considered ecological, economic, and social indicators. Cluster and principal components analysis were carried out to identify different groups of lava field remnants with similar characteristics and to point out critical variables that in turn would support management strategies. The outcomes made evident the necessity of restoring native vegetation for all of the evaluated remnants; however, the group containing the largest ones obtained the highest values for restoration feasibility and NFRI. The recovery of the rest of the remnants is critical to support the ecological restoration of the area as this may provide connectivity with better-preserved ecosystem remnants. When the restoration is unaffordable due to financial constraints, it is highly recommended to direct efforts towards ecological rehabilitation actions. The establishment of native xerophytic gardens is promoted when remnants cannot support a self-sustainable plant community. It is crucial to include the diversity of views and values of the community and the economic and ecological aspects to guarantee the sustainability of the landscape, especially in the urban context. The latter can provide better planning and design processes, ensuring benefits for humans and nature.

Unoccupied Aircraft Systems (UASs) Reveal the Morphological Changes at Stromboli Volcano (Italy) before, between, and after the 3 July and 28 August 2019 Paroxysmal Eruptions

In July and August 2019, two paroxysmal eruptions dramatically changed the morphology of the crater terrace that hosts the active vents of Stromboli volcano (Italy). Here, we document these morphological changes, by using 2259 UAS-derived photographs from eight surveys and Structure-from-Motion (SfM) photogrammetric techniques, resulting in 3D point clouds, orthomosaics, and digital surface models (DSMs) with resolution ranging from 8.1 to 12.4 cm/pixel. We focus on the morphological evolution of volcanic features and volume changes in the crater terrace and the upper part of the underlying slope (Sciara del Fuoco). We identify both crater terrace and lava field variations, with vents shifting up to 47 m and the accumulation of tephra deposits. The maximum elevation changes related to the two paroxysmal eruptions (in between May and September 2019) range from +41.4 to −26.4 m at the lava field and N crater area, respectively. Throughout September 2018–June 2020, the total volume change in the surveyed area was +447,335 m3. Despite Stromboli being one of the best-studied volcanoes worldwide, the UAS-based photogrammetry products of this study provide unprecedented high spatiotemporal resolution observations of its entire summit area, in a period when volcanic activity made the classic field inspections and helicopter overflights too risky. Routinely applied UAS operations represent an effective and evolving tool for volcanic hazard assessment and to support decision-makers involved in volcanic surveillance and civil protection operations.

CHILL-ICE: On-site Preparation for an Analogue Mission in Iceland

<p>CHILL-ICE (Construction of a Habitat Inside a Lunar-analogue Lava tub - Iceland Campaign EuroMoonMars) is focused on a safe and efficient preparation for future lunar human settlement for research, communication, and commercial purposes. In order to do so, a team of Early Career Scientists from EuroMoonMars will set up an analogue mission in the Stefánshellir lava tube on Iceland. The goal is to develop a prototype space habitat that can be transported into and set up in the lava tube by three (3) analogue astronauts; this means that they will be limited in their field of vision, have limited movement, have more momentum and a 'bigger body' to work with, and they will have limited amounts of time (in sim: 'Oxygen') available. Within eight (8) hours, they will need to set up the habitat and communication systems to give Mission Control (MC) the all-good. Failure to do so results in the termination of the mission and the analogue astronauts will be picked up again and transported back to MC.</p><p>In the scenario where the crew has complied with these mission objectives, they will spend two consecutive nights in the base and focus the rest of their time on research EVA's. These EVA objectives include: Robotics and rover operations, solar system observations, telecommunications, (RAMAN-)spectrometry, astrobiology, lava tube flow stratigraphy, and UAV-protocolling. To ensure an overall campaign success, there will be two of these short analogue astronaut campaigns, with a period of two days in between to adjust protocols where necessary and exchange information and lessons learned. </p><p>As a preparation for CHILL-ICE, there have been two earlier EuroMoonMars missions to Iceland to investigate the possibility and feasibility of an Icelandic lava tube campaign. In September 2018, we have scouted several locations to see what lava tube or lava field would be the optimal fit in terms of size, reachability, tourists or remoteness, medical support locations, earlier damage to the natural environment, and proper entrances. The decision was made to go to the Hallmundarhraun lava field, a 2-hour drive towards the Northeast of Reykjavik, the capital of Iceland. During an envoy mission in June 2020, we focused on specific lava tubes within this lava field, including Vidgelmir, Surtshellir, and Stefánshellir, where the choice was eventually made for the latter. The easternmost gallery of the Stefánshellir lava tube proved to be both wide and high enough to construct a habitat in, with a relative safe entrance via the skylight, reasonable natural lighting and airflow, connection to a larger subsurface system for astronautical and robotic exploration, and previous damage to the cave made it easier to get permits.</p><p>The current field campaign is planned from the 24th of May until the 6th of June and will also focus on (inter)national outreach and act as a basis for the national Icelandic space sector and their international relations.</p><p> </p><p>We would like to thank the previous EuroMoonMars teams for their support during this and the previous missions, as well as SpaceIceland, the IcelandicSpeleologicalSociety and our many other partners.</p><p> </p><p> </p>

Subsidence of the lava flow formed during 2012-2013 Tolbachik fissure eruption: SAR data and thermal model

<p>During the Tolbachik fissure eruption which took place from November 27, 2012 to September 15, 2013 a lava flow of area about 45.8 km<sup>2</sup> and total lava volume ~0.6 km<sup>3</sup> was formed. We applied method of persistent scatterers to the satellite Sentinel-1A SAR images and estimated the rates of displacement of the lava field surface for 2017–2019. The surface mainly subsides along the satellite’s line-of-sight, with the exception of the periphery of the Toludski and Leningradski lava flows, where small uplifts are observed. Assuming that the displacements occur mainly along the vertical, the maximum average displacement rates for the snowless period of 2017–2019 were 285, 249, and 261 mm/year, respectively. On the Leningradski and Toludski lava flows the maximum subsidence was registered in areas with the maximum lava thickness.</p><p>To estimate the thermal subsidence of the lava surface we constructed a thermal model of lava cooling. It provides subsidence rate which are generally close to the real one over a significant part of the lava field, but in a number of areas of its central part, the real subsidence values are much higher than the thermal estimates. According to the thermal model when lava thickness exceeds 40 meters, even 5 years after eruption under the solidified surface there can be a hot, ductile layer, which temperature exceeds 2/3 of the melting one. Since on the Leningradski flow, the maximum subsidence is observed in the area of the fissure along which the eruption took place, one could assume that the retreat of lava down the fissure could contribute to the observed displacements of the flow surface. Subsidence can also be associated with compaction of rocks under the weight of the overlying strata. Migration of non-solidified lava under the solidified cover, also can contribute to the observed distribution of displacements - subsidence of the surface of the lava field in the upper part of the slope and a slight uplift at its periphery.</p><p>The work was supported partly by the mega-grant program of the Russian Federation Ministry of Science and Education under the project no. 14.W03.31.0033 and partly by the Interdisciplinary Scientific and Educational School of Moscow University «Fundamental and Applied Space Research».</p>

Lava Flow Roughness on the 2014–2015 Lava Flow-Field at Holuhraun, Iceland, Derived from Airborne LiDAR and Photogrammetry

Roughness can be used to characterize the morphologies of a lava flow. It can be used to identify lava flow features, provide insight into eruption conditions, and link roughness pattern across a lava flow to emplacement conditions. In this study, we use both the topographic position index (TPI) and the one-dimensional Hurst exponent (H) to derive lava flow unit roughness on the 2014–2015 lava field at Holuhraun using both airborne LiDAR and photogrammetric datasets. The roughness assessment was acquired from four lava flow features: (1) spiny lava, (2) lava pond, (3) blocky surface, and (4) inflated channel. The TPI patterns on spiny lava and inflated channels show that the intermediate TPI values correspond to a small surficial slope indicating a flat and smooth surface. Lava pond is characterized by low to high TPI values and forms a wave-like pattern. Meanwhile, irregular transitions patterns from low to high TPI values indicate a rough surface that is found in blocky surface and flow margins. The surface roughness of these lava features falls within the H range of 0.30 ± 0.05 to 0.76 ± 0.04. The roughest surface is the blocky, and inflated lava flows appear to be the smoothest surface among these four lava units. In general, the Hurst exponent values in the 2014–2015 lava field at Holuhraun has a strong tendency in 0.5, both TPI and Hurst exponent successfully derive quantitative flow roughness.

Diachronous Tibetan Plateau landscape evolution derived from lava field geomorphology

<p><strong>Evolution of the Tibetan Plateau is important for understanding continental tectonics because of its exceptional elevation (~5 km above sea level) and crustal thickness (~70 km). Patterns of long-term landscape evolution can constrain tectonic processes, but have been hard to quantify, in contrast to established datasets for strain, exhumation and paleo-elevation. This study analyses the relief of the bases and tops of 17 Cenozoic lava fields on the central and northern Tibetan Plateau. Analyzed fields have typical lateral dimensions of 10s of km, and so have an appropriate scale for interpreting tectonic geomorphology. Fourteen of the fields have not been deformed since eruption. One field is cut by normal faults; two others are gently folded with limb dips <6<sup>o</sup></strong><strong>. </strong><strong>Relief of the bases and tops of the fields is comparable to modern, internally-drained, parts of the plateau, and distinctly lower than externally-drained regions. The lavas preserve a record of underlying low relief bedrock landscapes at the time they were erupted, which have undergone little change since. There is an overlap in each area between younger published low-temperature thermochronology ages and the oldest eruption in each area, here interpreted as the transition </strong><strong>between the end of significant (>3 km) exhumation and plateau landscape development. </strong><strong>This diachronous process took place between ~32.5<sup>o</sup> - ~36.5<sup>o</sup> N between ~40 and ~10 Ma, advancing northwards at a long-term rate of ~15 km/Myr. Results are consistent with incremental northwards growth of the plateau, rather than a stepwise evolution or synchronous uplift.</strong></p>

Thermodynamic model of chemical re-magnetization on the example of Girvas paleovolcano of the Onega structure of Karelian craton

Volcano Girvas is a complexly constructed volcano complex of the Yatuli age. Apparently, it is a shield lava volcano, which was probably one of the supply channels of the vast lava field of the western Prionezhie region within the Girvas volcanic zone. Despite the fact that the Girvassky volcano is bare only fragmentary, the structure of the current is perfectly preserved in the rocks, allowing to reconstruct the direction of flow. Among these rocks, there is a zone of postvolcanic hydrothermal changes in the rocks, consisting mainly of nesting and veined tourmalization and silicification, as well as subsequent epidotization, sulfidization, chloritization and albitization. The zones of secondary changes are confined to faults, while their spatial-temporal correlation remains unclear. Reconstruction of the geological structure showed that there were two main processes at the Girvasa volcano: 1) pneumatolysis of type due to magmatic gases separated from gabbro-dolerite sills, 2) heating and circulation of exogenous waters with formation of near propylites. Based on the proposed scheme, thermodynamic modeling was performed.