Damage Proxy Map of the Beirut Explosion on 4th of August 2020 as Observed from the Copernicus Sensors

On the 4th of August 2020, a massive explosion occurred in the harbor area of Beirut, Lebanon, killing more than 100 people and damaging numerous buildings in its proximity. The current article aims to showcase how open access and freely distributed satellite data, such as those of the Copernicus radar and optical sensors, can deliver a damage proxy map of this devastating event. Sentinel-1 radar images acquired just prior (the 24th of July 2020) and after the event (5th of August 2020) were processed and analyzed, indicating areas with significant changes of the VV (vertical transmit, vertical receive) and VH (vertical transmit, horizontal receive) backscattering signal. In addition, an Interferometric Synthetic Aperture Radar (InSAR) analysis was performed for both descending (31st of July 2020 and 6th of August 2020) and ascending (29th of July 2020 and 10th of August 2020) orbits of Sentinel-1 images, indicating relative small ground displacements in the area near the harbor. Moreover, low coherence for these images is mapped around the blast zone. The current study uses the Hybrid Pluggable Processing Pipeline (HyP3) cloud-based system provided by the Alaska Satellite Facility (ASF) for the processing of the radar datasets. In addition, medium-resolution Sentinel-2 optical data were used to support thorough visual inspection and Principal Component Analysis (PCA) the damage in the area. While the overall findings are well aligned with other official reports found on the World Wide Web, which were mainly delivered by international space agencies, those reports were generated after the processing of either optical or radar datasets. In contrast, the current communication showcases how both optical and radar satellite data can be parallel used to map other devastating events. The use of open access and freely distributed Sentinel mission data was found very promising for delivering damage proxies maps after devastating events worldwide.

Early vegetation recovery after the 2008-2009 explosive eruption of the Chaitén Volcano

In May 2008, Chaitén volcano entered in eruptive process, one of the world largest eruptions in the last decades. The catastrophic event left different type of disturbance and caused diverse environmental damage distributed heterogeneously in the surrounding areas of the volcano. We went to the field to assess the early vegetation responses a year after the eruption, in September 2009. Particularly, we evaluated the lateral-blast disturbance zone. We distributed a set of plots in three disturbed sites, and one in an undisturbed site. In each of these sites, in a plot of 1000m2 we marked all stand tree, recording whether they were alive, resprouting or dead. Additionally, in each site 80 small-plots (~4m2) we tallied the plants regeneration, its coverage, and the log-volume. We described whether the plant regeneration was growing on mineral or organic substrate. In the blast-zone the eruption created a gradient of disturbance. Close to the crater we found high devastation marked by no surviving species, scarce standing-dead trees and logs, as well as no tree regeneration. On the other extreme of the disturbance gradient, the trees with damaged crown were resprouting, small-plants were regrowing and seedlings were more dispersed. The main regeneration strategy was the resprouting of trunks or buried roots, while few seedlings were observed in the small plots and elsewhere in disturbed areas. However, the assessment was too soon after the eruption and updated monitoring is required to confirm observed patterns. The main findings of this study are: i) a mosaic of pioneering-wind dispersed species, scattered survivors regrowing and spreading from biological legacies, and plant species dispersed by frugivorous birds, likely favored by the biological legacies; (ii) the early succession is influenced by the interaction of the species-specific life history, altitudinal gradient and the different intensity of disturbance.

Summer foraging ecology of wapiti (Cervus elaphus roosevelti) in the Mount St. Helens blast zone

Summer–fall foraging behavior of wapiti was studied relative to seasonal changes in forage resources in early successional forests of the Mount St. Helens "blast zone." Seasonal changes in diet, plant community selection, and foraging behavior of wapiti were generally consistent with hypothesized ingestive and processing constraints on a large-bodied ruminant. When high-quality forage was abundant early in the growing season, forbs dominated in wapiti diets probably because of their high digestibility and cell-wall breakdown rates. As forb biomass declined, wapiti initially maintained a high intake of forbs by increasing search rates (m/min). Eventually wapiti switched to grasses, with consequent decreases in feeding time and increases in rumination time. Selection of plant communities by wapiti was related to the standing crop (kg/ha) of forage only in the fall, when grasses were the preferred forage type. Cover and spacing needs during calving and the influence of forage structure on intake rates and plant community selection are discussed.