Aerosol-cloud interactions are the most uncertain component of the Earth system, due to their major influence on cloud properties, and as a result, Earth’s energy budget. We need to better characterize these interactions, which requires constraining the cloud condensation nuclei (CCN) budget and disentangling the influences of aerosol microphysics from meteorology. Observational data are essential for evaluating and improving climate models, but airborne field campaigns have, until recently, been limited to a few (mostly continental) regions worldwide. CCN measurements over the remote ocean are scarce and only occur during extensive field missions involving airborne or ship-based measurements of limited spatial and temporal extent. Polar-orbiting satellite observations hold great promise for expanding the spatial coverage of observations to remote regions, however, it is currently not well understood to what extent these active and passive remote sensing observations can be considered adequate proxies for CCN. Recent literature make use of column integrated retrievals, such as aerosol optical depth or aerosol index, to characterize aerosol concentration and CCN, and the utility of vertically resolved optical properties from active sensors is only now becoming more fully understood. The NASA ACTIVATE, NAAMES, CAMP2EX and ORACLES field campaigns are particularly well suited for evaluating the skill of advanced satellite aerosol and cloud microphysical retrievals, given the comprehensive suite of airborne aerosol, cloud, and trace gas measurements, combined with airborne High Spectral Resolution Lidar (HSRL) and polarimetric imaging instruments that will be the basis for the next generation of space-based remote sensors. Here, we characterize the properties of aerosol and CCN from these NASA field campaigns and critically assess methods for deriving CCN and CCN proxies using visible and infrared satellite remote sensing retrievals.

Okmok volcano on Umnak Island, Alaska is one of the most hazardous, explosive volcanoes in the Aleutians. Most recently, it erupted in 2008. Previous seismic imaging of Okmok’s large caldera system revealed complex magmatic structures in the upper 5 km beneath the caldera but magma transport at larger depths remains poorly constrained due to reduced imaging resolution. Using receiver function analysis of waveforms, we aim to chart sharp boundaries in the crust beneath Okmok and the surrounding region in order to understand its deeper crustal magmatic system. We have calculated receiver functions for M6 and larger teleseismic earthquakes between 2008 and 2021 recorded by permanent networks AV and AK, and between 2015-2016 at temporary network 5F. We observe Ps arrivals that are consistent with a Moho depth of ~40km, particularly at stations outside the caldera. At some stations, we observe that receiver functions calculated for incoming rays pointing towards the volcano are different from those pointing away from the volcano. However, there is significant variability in the receiver functions, even for overlapping ray paths in the mid-to-deep crust (> 10 km). This suggests complex crustal structure with heterogeneity that may be spatially localized beneath individual stations. Furthermore, receiver functions for stations inside Okmok caldera are more reverberatory than those outside the caldera, indicating that the structure, likely predominantly in the upper crust, beneath these two regions is different.

In recent decades, major growth is observed in wildfire incidents across the globe. These ecological disasters, triggered by natural and/or anthropogenic factors, can have long-lasting effects on the environment, ecosystems, and biodiversity. Advancements in remote sensing technology provided an impetus to forest fires research, enabling precise determination of the geographical locations susceptible to fire and assess fire risk. This study focuses on India, whose total forest cover (71.22 Mha) is about 21.67% of the country’s total geographical area. Around 90% of the forest fires in India are attributable to anthropogenic factors. Therefore, the generation of a forest fire risk map (FRM) is essential for devising strategies to mitigate/manage forest fires and avert their disastrous impacts. An attempt is made to develop FRM for the Budhabalanga river basin, which contains the Similipal national park, a part of the UNESCO World Network of Biosphere Reserves. For this purpose, covariates affecting forest fire are identified viz. fuel (vegetation), topographic features (elevation, aspect, and slope), and human activities. The covariates are assigned weights, depicting their relative importance in influencing the fire, byusing Analytical Hierarchical Process (AHP). The AHP is a widely used technique in multi-criteria decision-making models. The Similipal national park has experienced a prolonged dry spell and below-average monsoon in 2020. The consequent dry conditions led to a significant forest fire event in the last week of February 2021, which lasted nearly three weeks. Fine (30m) resolution satellite data (Landsat-8) are used to calculate the Normalized Difference Vegetation Index (NDVI) corresponding to the study area to assess vegetation conditions before the fire event. Furthermore, Cartosat-1 Digital Elevation Model (24m resolution) is used to extract topographic-related information. The FRM generated for the basin using the assigned weights was 80% accurate when validated with 375m resolution NASA’s VIIRS (Visible Infrared Imaging Radiometer Suite) fire point data for the analyzed fire event. Hence, the methodology considered for developing FRM appears promising. It can be extended to other river basins for identifying fire risk zones and devise timely strategies to mitigate fire risk.

The Gangdese arc magmatism was active in response to the Mesozoic subduction of the Neo-Tethyan oceanic lithosphere and the Cenozoic collision between the Indian and Asian continents. The Paleocene Gangdese batholith in southern Tibet is intruded by several voluminous peraluminous leucogranites, with the origin of these leucogranites remaining controversial. In this study, we investigate a small garnet-bearing leucogranite intrusion in the Nyingchi Complex that represents the exposed lower crust of the Lhasa Terrane and underwent multi-stages of amphibolite- to granulite-facies metamorphism since the Cretaceous. Bulk-rock mineralogy and geochemistry display S-type granite signatures, indicating its anatexic origin. The center of the ~300 m-wide pluton contains abundant garnet in a perthite-quartz matrix. The garnets, from core to rim, display stepwise concentrations of major and rare earth elements, indicating multiple stages of growth. The cores are featured by three groups of oriented needles of rutile, which are regarded as products of exsolution due to rapid decompression or cooling and have been found almost exclusively in extreme temperature and/or pressure conditions. The Ti-in-rutile temperatures range from 900 to 850 oC, consistent with the temperatures derived from the ternary feldspar thermometer. These rutile-rich garnet cores were likely seeded from the lower crustal resitites and incorporated in an upwelling of hot mantle-derived magma. The peritectic garnet mantle continued to grow in the melt at 800-650 oC, as suggested by the Zircon saturation temperature and the Ti-in-zircon thermometer. The diffusion profiles between the Ti-rich core and mantle yield a short ~25 kyr duration of cooling from 870 °C to 700 °C, when the leucogranite magma migrated and emplaced. Zircons from the granite show complex textures; most of the cores and magmatic mantles yield U-Pb ages between 60 and 50 Ma, suggesting a syn-collisional origin of the melt. We speculate that the Paleogene slab roll-back and slab break-off would have resulted in enhanced asthenospheric corner flow and upwells, supplying a long-lived heat source for coeval crustal anatexis and metamorphism in southern Lhasa during the early phase of continental collision.

The broadband stacks (templates) of velocity seismograms of nearly co-located low-frequency earthquakes (LFEs) detected using a 1-8 Hz passband beneath southern Vancouver Island tend to exhibit a simple dipolar shape with a characteristic duration of ~0.3-0.5 s, which is also found to be nearly independent of the seismic moment. An important question left unanswered is whether the duration is due to the nature of the source, is set by attenuation near the source region, or is just a bias introduced by the narrow passband used to detect LFEs. In tremor catalogs detected using a relatively low-frequency passband, 0.5-1.25 Hz, we have found some tremor windows that contain relatively isolated dipole arrivals similar to LFEs. A few of these have a duration apparently longer than that of the LFE templates. Notably, the same location on the fault also seems capable of generating signals with a shorter duration at other times. Figure 1 shows seismograms, at 3 stations, of one such example in the vicinity of LFE family 001 of Bostock et al. (2012), in which the main arrival has a duration of ~1 s, whereas another signal 3 s earlier with a duration of only ~0.4 s comes from roughly the same location (same move-out between the stations). This significant variability in duration at approximately the same location suggests that the long-duration events owe their duration to source processes and not attenuation, provided that attenuation does not vary on extremely short time and space scales during the episodic tremor and slip episode. The relative isolation in time also makes the longer duration less likely to result from the temporal clustering of multiple typical LFEs. We will undertake a more systematic search of our longer- and shorter-period tremor catalogs to assess this possibility. Addressing this question will shed more light on the factors that control the apparent duration of LFEs. Figure 1 The top panel shows the long-duration tremor signal in a relatively lower-frequency band, 0.5-1.25 Hz, whereas the second panel from the top is the same 32-s segment in a higher-frequency band, 1.25-6.5 Hz. The third panel shows the trace in a broader passband, 0.5-6.5 Hz. The bottom panel shows the stacked LFE templates of the same family filtered through 0.5-6.5 Hz.

Geodetic data provide an opportunity to improve our understanding of the processes and parameters controlling the dynamics of deformation during the earthquake cycle at subduction zones. However, the observations contain noise and are temporally and spatially sparse, whereas dynamical models are unequivocally imperfect. Also, the relative contributions from various drivers of surface deformation are poorly constrained by independent observations. Some drivers may be static or vary slowly in time (e.g., plate motion), whilst others vary significantly during the earthquake cycle (e.g., viscoelastic relaxation). Data assimilation combines prior estimates of dynamical models, with the likelihood of observations into posterior estimates of the state evolution and time-independent parameters of a physical process. We explore the usefulness of data assimilation by using a particle filter to estimate the (spatially variable) elastic thickness of the overriding plate and the extent of the locked zone. We assimilate vertical interseismic surface displacements into a 2D elastic flexural model. The particle filter uses a Monte Carlo approach to represent the state probability distribution by a finite number of realizations (“particles”). We use sequential importance resampling to preserve particles statistically close to the observations and duplicate and perturb them. Synthetic experiments demonstrate that the particle filter effectively estimates 1D elastic thickness from synthetic observations. However, elastic thickness estimates for models with a landward increase in plate thickness show larger uncertainty near the coast as the sensitivity of surface displacements reduces with increasing plate thickness. Interestingly, the effectiveness of the elastic thickness estimation is highly sensitive to network aperture, including GPS/A. Assimilation of interseismic vertical velocities prior to the 2011 Tohoku-Oki earthquake yields estimates of upper plate thickness that agree with previous studies. However, results of the locked zone extent are not as expected, which could be due to missing physics in the relatively conceptual model. These results demonstrate the potential of the particle filter to better understand the geodynamic process parameters of the earthquake cycle at subduction zones.

We exploit novel “string-of-pearls” configuration of NASA’s Magnetospheric Multiscale mission to investigate properties of structures within the Earth’s magnetosheath that are short in duration but carry intense currents. Previous work has shown that the j.E energy conversion within current structures processes of order 10% of the total energy flux incident at the bow shock. This makes these events important contributors to the overall shock energy budget and ongoing thermalization within the magnetosheath. The present study, under very similar solar wind conditions and bow shock geometries, reveals significant qualitative differences from the previous study. Moreover, we find only modest, if any coherence, on scales <1000 km. We explore the implication of these observations in terms of both bow shock and turbulence energy transfer and dissipation.

Carbonates have been detected in several locations on Mars, including Nili Fossae, Jezero Crater, and the Comanche outcrops of the Columbia Hills. Carbonates are intriguing for what they could reveal about potential habitability of past environments; however, their exact formation mechanisms remain ambiguous. Observations support a range of formation mechanisms, such as meteoric alteration of hot olivine tephra, hydrothermal alteration or serpentinization, near-surface weathering of serpentinized material, or aqueous alteration via ephemeral lakes. The associated mineralogy of carbonate-bearing terrain, such as the serpentine deposits detected in Nili Fossae and Jezero, can help constrain the origins of the carbonates. This study examines CRISM and HiRISE images of serpentine and carbonate deposits in Nili Fossae and Jezero Crater to identify common characteristics of serpentine-carbonate terrains. The morphologies of serpentine and carbonate-bearing terrains in Nili Fossae and Jezero are then compared to carbonate deposits in the Columbia Hills. By combining these analyses, this study explores the extent to which the carbonates’ histories are analogous and probes into previous serpentine detections in Jezero and Nili Fossae.

Land-use decisions, particularly in an agricultural setting, lie at the nexus of the colliding challenges of climate change and food insecurity. Understanding and guiding these decisions at the regional scale is a key strategy in the development of natural climate solutions and sustainable food production systems. These issues come together in a particularly high-stakes context in the Massachusetts cranberry industry, which occupies a position of significant economic and sociocultural importance in the region, but faces a number of challenges in the form of heightened competition, unstable prices, an aging farmer population, and changing ecological conditions. Many farmers are looking either for ways to become profitable, or to exit the industry in a financially sustainable way. One option is to sell their land to developers; another option, which is exciting to scientists and environmental advocates, is undergoing an active habitat rehabilitation to restore the beneficial ecosystem services of a functioning wetland environment. Integrating satellite data and in-situ sensor data collected over the past decade, we aim to conduct a systems analysis that unites the viewpoints of cranberry industry stakeholders and clarifies the trade-offs between environmental, economic, and social factors in the region. We propose to address this aim via three core research efforts: a contextual analysis of the industry; a valuation and mapping of key ecological, economic, and social factors; and an integrated modeling approach that models interactions and trade-offs between these factors. In particular, this presentation will focus on the progress we have made valuing and mapping key environmental and economic factors using publicly available satellite imagery and census data. This work demonstrates how these factors align with existing features of the natural and built environment, supports conservation organizations and municipalities in their restoration and conservation advocacy, and provides a foundation for future scenario mapping that will analyze trade-offs in different land use cases.

Over the past 15 years climate tipping points (CTPs) – which are reached when change in a climate subsystem (the ‘tipping element’) becomes self-perpetuating independent of the original forcing and results in a regime shift to a new subsystem state – have emerged as a source of scientific and public concern. Some CTPs are estimated to be reachable within the 1.5-2oC Paris Agreement range, with many more accessible by the ~3-4oC of warming possible on current policy trajectories. Recent work has also hypothesised that CTPs could ‘cascade’ – with the impacts of triggering one tipping element sufficient to trigger the next and so on – resulting in an emergent global tipping point. However, much discussion relies on a tipping element characterisation that is now over a decade old, which itself was based on an expert elicitation exercise in 2005. Since then there have been substantial advances in our understanding of CTP dynamics based on results from coupled and offline models, observations, and palaeoclimate studies. The tipping cascade hypothesis has also not yet been rigorously tested, with the suggestion of 2oC as a global tipping point remaining speculative. Furthermore, CTP definitions are often inconsistent, with some purported globally-impactful CTPs more accurately represented as either localised CTPs or even threshold-free feedbacks. Here we undertake an updated review of CTPs based on a wide range of recent literature. We estimate ranges for each proposed element’s tipping threshold, timescales, and impact on global and regional warming, as well as if evidence exists for self-perpetuation, rate-dependence, or hysteresis. Each proposed element is then catalogued with reference to a clear tipping point definition, separating global ‘core’ and regional ‘impact’ tipping elements from threshold-free feedbacks. Our estimates confirm that current global warming (~1.2oC) already lies within the lower end of some CTP threshold ranges, and several CTPs become likely or possible within the 1.5-2oC Paris range. In further work we use these estimates to test the potential for and impact of tipping cascades in response to global warming scenarios using a stylised model.

The U.S. and much of the world sit on the cusp of an electrification revolution – a moment driven largely by the need to reduce the emission of greenhouse gases to limit the impacts of anthropogenic climate change. The electrify everything movement aims to transition combustion-powered sectors into technologies powered solely by electricity, with the idea that the electric grid – currently comprised of a mix of combustion, renewable, and nuclear generation units – will become cleaner and greener over time. Studies indicate that electrifying high-efficiency devices, appliances, and vehicles will reduce greenhouse gas emissions regardless of the grid’s composition, however ancillary air quality benefits and tradeoffs remain poorly resolved, particularly at impact- and equity-relevant scales. Here, I use a fine-scale CONUS-wide climate and air quality co-benefit and tradeoff analysis framework (i.e., 4 km2 SMOKE-CMAQ-WRF simulations) to assess sustainable climate solutions. Analyses utilize emission scenarios that account for increased grid demand and uncertainties in grid evolution, simulate the interaction of meteorological and chemical processes, characterize changes in greenhouse gases and air pollutants, and assess economic, social, and public health consequences of sustainable transitions over two key, yet methodologically disparate, residential/commercial sectors: transportation: via the replacement of internal combustion vehicles with electric vehicles and lighting: via the replacement of low efficiency bulbs with high-efficiency LEDs.

The Nankai Trough is a locus of slow slips, low frequency, and large-magnitude classical earthquakes. It is assumed that high pore pressure contributes substantially to earthquake dynamics. Hence, a full understanding of the hydraulic regime of the Nankai accretionary prism is needed to understand this diversity of behavior.We contribute to understanding the full hydraulic regime within the Nankai accretionary prism by innovatively integrating the drilling and logging data of the NanTroSEIZE project. We focus on the toe of the Nankai accretionary prism by studying data from hole C0024A drilled during IODP expedition 358. This drilled hole intersected the Nankai décollement at 813 mbsf, about 3 km from the trench. Pore pressure was first estimated using Eaton’s method on both drilling and sonic velocity data. Both results show that pore pressure follows hydrostatics until the top of the hemipelagites, with local pore pressure rising up to 38% above hydrostatic especially crossing the décollement. Downhole Annular Pressure was also monitored during drilling, and a careful reanalysis of its variation shows the occurrence and the locus of fluid flow between the formation and the borehole. Primarily, there are two identified fluid flow anomalies intervals: (1) at the shallow depths <100 mbsf with loose coarse sediments, which could be related to erosional unloading, landslide, slope instability. (2) Below the décollement (<813 mbsf) at the two asymmetric damage zones. The damage zones at the footwalls of the major faults are predominantly permeable with significant porosity and permeability values with orders of magnitude between ∼10−16 to 10−17 m2 as quantitatively estimated using the Hvorslev equation for a fully penetrating well in a confined aquifer. Our results show that the formation fluids are getting significantly over-pressurized only a few hundred meters from the toe of the décollement. The décollement is already impermeable across the fault, and the fluid flow is channelized along the damage zones. The impermeable décollement acts as a hydraulic barrier inhibiting fluid flow upward, keeping high pore pressure at the footwall and increasing the structural weakness of the lithologies. It’s therefore probable that high pressure is also expected further down in the locus of tremors and slow slip events.

In many streams, discharge is often anticipated to be the residual between the inputs to watersheds (precipitation, groundwater inputs), outputs (evapotranspiration, groundwater outflow), and changes to water storage. This basic water balance approach fails to capture many of the aspects that drive streamflow, namely the sequence between fluxes and storages that must occur prior to streamflow generation. This is further complicated by the limitations of ever estimating total water storage, namely due to subsurface heterogeneity, poorly defined boundary conditions, and difficulties of associated with measuring certain fluxes (GW in and outflows) and storage reservoirs (soil water). From a hillslope perspective, the relationship between watershed storage and discharge is not so linear. There are sequences of storage thresholds which must be breached prior to other storage units being activated. As storage units fill (i.e., fill and spill storage + surficial soil storage) they activate other hydrologic processes (percolation) that spurs the filling of other storage components (groundwater storage). These thresholds are complex, time varying, with non-linear and hysteretic activations, and result in much more complex transit times than a simple water balance would suggest. We use records from ~13 years of intensive hydrologic monitoring at 3 adjacent low-relief, groundwater driven headwater streams that drain the Savannah River Site in the Upper Atlantic Coastal of Plain to explore the sequential storage thresholds that govern stream discharge at the site. Coupled with a spatially discrete water table model and remotely sensed estimates of surface water storage, we provide a more robust estimate of total water storage and help elucidate how much water is going unmeasured via deep groundwater flow pathways

Elevated organic matter (OM) concentrations are found in hadal surface sediments relative to the surrounding abyssal seabed. However, the origin of the biological material remains elusive. Here, we report the composition and distribution of cellular membrane intact polar lipids (IPLs) extracted from surface sediments around the deepest points of the Atacama Trench and adjacent bathyal margin to assess and constrain the sources of labile OM in the hadal seabed. Multiscale bootstrap resampling of IPLs’ structural diversity and abundance indicates distinct lipid signatures in the sediments of the Atacama Trench that are more closely related to those found in bathyal sediments than to those previously reported for the upper ocean water column in the region. While the overall number of unique IPL structures in hadal sediments is limited and they contribute a small fraction of the total IPL pool, they include a high contribution of phospholipids with mono- and di-unsaturated fatty acids that are not associated with photoautotrophic sources. The diversity of IPLs in hadal sediments of the Atacama Trench suggests the presence of in situ microbial production and biomass that resembles traits of physiological adaptation to high pressure and low temperature, and/or the transport of labile OM from shallower sediment. We argue that the export of the most labile lipid component of the OM pool from the euphotic zone and the overlying oxygen minimum zone into the hadal sediments is neglectable. Our results contribute to the understanding of the mechanisms that control the delivery of labile OM to this extreme deep-sea ecosystem. Furthermore, they provide insights into some potential physiological adaptation of the in situ microbial community to high pressure and low temperature through lipid remodeling.

Estimating the fraction of photosynthetically active radiation absorbed by vegetation (i.e., fPAR) is crucial for quantifying the carbon uptake activity of terrestrial ecosystems. Satellite-derived vegetation index (i.e., NDVI) is the powerful indicator of fPAR, enabling us to capture spatiotemporal variations in ecosystem carbon uptake activity. Since 2015, Sentinel-2 having about 3-day of revisit interval and 10 m of spatial resolution has been operated. This study evaluates the relationship between ground observed fPAR and Sentinel-2 derived NDVI in four temperate forests in Niigata prefecture, central Japan. Briefly, fPAR for April to July (from 0.44 to 0.96) varied depending on the seasons and the forest ages and types (i.e., two young mixed forests, a mature mixed forest, and a mature needleleaf forest). In the two young mixed forests and the mature needleleaf forest, NDVI was positively correlated with fPAR (r = 0.81 to 0.99), where a 0.1 increase in NDVI implied a 0.2 increase in fPAR. However, the correlation between NDVI and fPAR in the mature mixed forest was weak (r = 0.38 to 0.53). Thus, this study confirmed that the effectiveness of Sentinel-2 derived NDVI tracking spatiotemporal variations in fPAR and carbon uptake activity likely varied depending on types and ages of forests.

Over the last several decades, heat waves have notably increased in frequency, intensity, and duration in the United States. Studies have credited these trends to a warming climate, and therefore, it is expected that extended periods of consistent and abnormally hot temperatures will continue to occur through the 21st century. Heat waves alone can have harmful impacts on the human body, but when coupled with high humidity, these events can become especially threatening. While other studies have assessed the human health effects of extreme humid heat waves, this study aims to determine the source region and pathway of air parcels during these events, while also understanding the land-surface processes that amplify and dampen the amount of atmospheric moisture present as an air parcel reaches a target region. Through the use of the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, atmospheric moisture exchanges and concentrations are analyzed for the three days prior to a humid heat wave at Boston, MA, Burlington, VT, Albany, NY, and Philadelphia, PA, between June and August of 1980-2019. Four major source regions are identified as being largely responsible for the atmospheric moisture present during heat waves across these cities: the Atlantic Ocean, Gulf of Mexico, Great Lakes, and terrestrial evapotranspiration from the Midwest and Mid-Atlantic regions of the United States. Geographical location and proximity to water of each city has a notable influence on source region and number of humid heat waves occurring throughout the period of study. At Boston and Philadelphia, the two leading sources of moisture are the Atlantic Ocean and Gulf of Mexico, while at Burlington and Albany, the Great Lakes and terrestrial evapotranspiration are more dominant. Stark differences are also noted between the source regions and trajectories of humid versus dry heat waves at a given location. Examining the sources and paths of air parcels leading up to extreme heat events, as well as analyzing the atmospheric-land interactions that take place during that time, will provide a comprehensive understanding into the importance of a given moisture source region on a particular location, and how a warming climate may ultimately alter the degree to which a source region is responsible for atmospheric moisture in the future.

Although scarcely described, intense summer precipitation events in central Chile aren’t an unknown phenomenon, their recurrence is estimated at 40 years. In the last 5 years, 2 heavy rainfall episodes triggered massive debris flows in the San Jose de Maipo county of the Metropolitan Region, located on the upper Maipo river basin, where average precipitation for summer months is only 7 mm. A summary of the current knowledge of the January 28 to 31, 2021 summer rain event is presented. The episode has been attributed to a Zonal Atmospheric River (ZAR), which allowed for a direct transfer of vapour and moisture on a W-E trajectory perpendicular to the Chilean coast. The latter favoured high altitude precipitation, with 0 degree isotherm estimated at 3.700 m a.s.l. On a local range, the snow line was observed between 2,800-3,100 m a.s.l. The event precipitation reached unprecedented values over 60 mm on all stations along the Maipo valley, with a local maximum of 117 mm. 3 pulses have been accounted for rainfall, with a maximum intensity of 11 mm/hour; at the peak of the pulses the Maipo river flow increased 8 times its pre-event flow of 60 m/s. In the following days after the event, 55% of the Upper Maipo basin was covered with snow. Due to sudden higher temperatures a consequent rapid snow melt increased the turbidity of the Maipo river, compromising freshwater supply. Agriculture was also affected, mainly grapes. According to the National Geological and Mining Service, over 120 landslides were triggered during the event, most of them being debris flows with some rock fall affecting the main roads. 700 persons were affected, more than 100 houses resulted with damages, 50 with severe damages and 33 destroyed, mostly at the San Alfonso village. Cost of infrastructure’s lost was estimated over US$4MM. Luckily, there weren’t any fatalities. This feature contrasts with the 25 February 2017 debris flow episode in the same region, with 8 fatal victims. Although local inhabitants have coexisted with this kind of hazards since historical times, uninterrupted urban growth on mountain areas has contributed substantially to an increase in the level of exposure. In this case, the accurate forecasting of the ZAR coupled with an effective risk communication avoided fatalities, nonetheless, it is most likely that this kind of phenomenon will occur again.

Sudden Impulse (SI) events and Sudden Storm Commencements (SSC) are rapid geomagnetic variations associated with a compression of the magnetic field. Starting in 2006 Ebre Observatory, the IAGA international database on rapid magnetic variations, began to differentiate SI events from SSCs. These events have different magnetic characteristics depending on local time and latitude. Starting in 2006 and ending with the last definitive published dataset, the module SeaPy within Python is used to perform a superposed epoch analysis on SI events and SSCs for high latitude stations and low latitude stations. In relation to low latitude station onset times, we find systematic behavior of the total field strength and North-South component of the magnetic field at high latitudes. Specifically, the SI and SSC signatures are delayed and the compression signature can be highly variable from event to event.