Release Area Research Articles

A reappraisal of the 2005 Kashmir (Mw 7.6) earthquake and its aftershocks: Seismotectonics of NW Himalaya

We study the source properties of the 2005 Kashmir earthquake and its aftershocks to unravel the seismotectonics of the NW Himalayan syntaxis. The mainshock and larger aftershocks have been simultaneously relocated using phase data. We use back-projection of high-frequency energy from multiple teleseismic arrays to model the spatio-temporal evolution of the mainshock rupture. Our analysis reveal a bilateral rupture, which initially propagated SE and then NW of the epicenter, with an average rupture velocity of ~2 kms−1. The area of maximum energy release is parallel to and bound by the surface rupture. Incorporating rupture propagation and velocity, we model the mainshock as a line source using P- and SH-waveform inversion. Our result confirms that the mainshock occurred on a NE dipping (~35°) fault plane, with centroid depth of ~10 km. Integrated source time function show that majority of the energy was released in the first ~20 s, and was confined above the hypocenter. From waveform inverted fault dimension and seismic moment, we argue that the mainshock had an additional ~25 km blind rupture beyond the NW Himalayan syntaxis. Combining this with findings from previous studies, we conjecture that the blind rupture propagated NW of the syntaxis underneath a weak detachment, overlain by infra-Cambrian salt layer, and terminated in a wedge thrust. All moderate-to-large aftershocks, NW of the mainshock rupture, are concentrated at the edge of the blind rupture termination. Source modeling of these aftershocks reveal thrust mechanism with centroid depths of 2–10 km, and fault planes oriented sub-parallel to the mainshock rupture. To study the influence of mainshock rupture on aftershock occurrence, we compute Coulomb failure stress on aftershock faults. All these aftershocks lie in the positive Coulomb stress change region. This suggest that the aftershocks have been triggered by either co-seismic or post-seismic slip on the mainshock fault.

An evaluation of a catch and release trout regulation in Rapid Creek, South Dakota

Often, catch and release regulations are meant to maximize a fisheries potential to create trophy fish. I evaluated adult Brown Trout populations at five locations within Rapid Creek within Rapid City, SD over a two-year period. In each year, one of these locations was within a catch and release area, while two were outside. In 2012, density and biomass estimates were higher in a site located outside of the catch and release area. Additionally, size structure within the catch and release area was only significantly larger than one of the two sites outside of the regulation area. Mean relative weight values were inversely related to density estimates, with the lowest density sites having the highest mean relative weights. Similarly, a site outside of the catch and release area had the highest abundance and biomass estimates in 2013. The cumulative length distribution was significantly different between the site within the catch and release area and the two located outside. Relative weight was significantly higher in the catch and release area than the two sites outside. As population characteristics within the catch and release area were not consistently better than outside, it is more likely that factors such as habitat and density dependence are impacting the Brown Trout population more than the regulation itself.

Harmonized mapping of forests with a protection function against rockfalls over European Alpine countries

Forest covers 40% of the European Alpine region and contributes to the protection of human beings and infrastructures against natural hazards such as rockfalls. However, despite the recognition of this ecosystem service, most mountain territories do not have a map of protection forests. When a map exists, it generally depends on data restricted to a limited extent, which prevents any replication or comparison on other areas. The aim of this study is to develop a method using harmonized and open data to produce the first map of protection forests against rockfalls at the European Alpine region scale. Based on these data, we first identified potential rockfall release areas and calibrated the model according to 2812 real rockfall events located around the Alps. Second, 46.5 billion 3-D rockfall propagation simulations, taking into account topography, land use and human assets, were computed on the entire area. Protection forest is defined as being located on at least one rockfall trajectory that had impacted human assets. Our results show that 14% of the forests have a potential protection function against rockfalls in the Alpine Space region. This proportion goes up to 21.5%, if we consider only the core of the Alpine area. 80% of the protection forest area contributes to mitigate rockfall hazard on road network, 55% on buildings and only 6% on railways. This work provides a robust, objective and reproducible method for locating protection forests on a large geographical scale. Such a map may serve as a basis for national and European risk management policies.

A novel method for captive rearing and translocation of juvenile common loons.

Common loons (Gavia immer) are diving waterbirds that are particularly challenging to keep in captivity due to their specific behavioral and physiologic needs, special housing requirements, and susceptibility to stress-related disease. We report a novel method for housing and captive rearing common loon chicks that was developed as part of the first-ever loon translocation effort in southeast Massachusetts,from 2015 to 2017. Thirteen loon chicks were reared in aquatic pens in a natural lake environment, utilizing noninvasive feeding and monitoring techniques that avoided human habituation. Chicks were reared in aquatic pens for 16-28 days before being released onto the lake. All chicks remained clinically normal and were monitored on the lake for up to 4 months following release. At least four of the chicks were subsequently confirmed to have survived to adulthood when they returned to the area in breeding plumage two to 3 years following release. Two of these confirmed adults displayed prolonged territorial pair behavior together, and this is an encouraging early sign that captive-reared individuals may form successful breeding pairs in the future. Because most immature loons remain on the ocean until at least 3 years of age, we expect additional captive-reared loons to return to the release area in subsequent years. These husbandry techniques could be applied to other loon and diving bird species that are notoriously difficult to house in captivity. The novel feeding techniques described here could also be adapted for loon chicks being reared in pools or other traditional captive settings.

Impacts of land-cover changes on snow avalanche activity in the French Alps

Abstract Dendrogeomorphic analyses provide long and continuous chronologies of mass movements that are useful for the detection of trends related to climate change. Socio-environmental changes can, however, induce non-stationarities. This study addresses the following questions: (1) How does the evolution of forest cover induce non-stationarities in tree-ring based reconstructions of snow avalanche activity? (2) How are trends inherent to tree-ring approaches distinguishable from real fluctuations in avalanche activity? Using dendrogeomorphic techniques, we reconstructed snow avalanches in six adjacent paths in the French Alps. Results show two distinct trends in process activity between 1750 and 2016. In the southern paths, the frequency of snow avalanches increased sharply in the 1970s. The distribution of tree ages, as well as old topographic maps, allow an attribution of this trend to the destruction of large parts of the forest stand by a large snow avalanche in the 1910−20 s. This extreme event induced a sudden change in the capability of newly colonizing trees to record subsequent snow avalanches. In the northern paths, by contrast, progressive afforestation starting in the mid-19th century, as well as colonization of the release areas after World War II, resulted in a strong reduction in snow avalanche activity since the 1930s. Even if global warming remains a possible additional driver of snow avalanche activity at the study sites, the rural exodus and the abatement of pastoral practices during the 19th and 20th centuries are the main explanations for the observed trends in process activity. Results also illustrate a need to clarify the complex interrelations among forest evolution, global warming, social practices, and the process activity itself when interpreting trends in mass movements.

Efficient production of male Wolbachia-infected Aedes aegypti mosquitoes enables large-scale suppression of wild populations.

The range of the mosquito Aedes aegypti continues to expand, putting more than two billion people at risk of arboviral infection. The sterile insect technique (SIT) has been used to successfully combat agricultural pests at large scale, but not mosquitoes, mainly because of challenges with consistent production and distribution of high-quality male mosquitoes. We describe automated processes to rear and release millions of competitive, sterile male Wolbachia-infected mosquitoes, and use of these males in a large-scale suppression trial in Fresno County, California. In 2018, we released 14.4 million males across three replicate neighborhoods encompassing 293 hectares. At peak mosquito season, the number of female mosquitoes was 95.5% lower (95% CI, 93.6-96.9) in release areas compared to non-release areas, with the most geographically isolated neighborhood reaching a 99% reduction. This work demonstrates the high efficacy of mosquito SIT in an area ninefold larger than in previous similar trials, supporting the potential of this approach in public health and nuisance-mosquito eradication programs.

Population Dynamics of Underdominance Gene Drive Systems in Continuous Space.

Underdominance systems can quickly spread through a population, but only when introduced in considerable numbers. This promises a gene drive mechanism that is less invasive than homing drives, potentially enabling new approaches in the fight against vector-borne diseases. If regional confinement can indeed be achieved, the decision-making process for a release would likely be much simpler compared to other, more invasive types of drives. The capacity of underdominance gene drive systems to spread in a target population without invading other populations is typically assessed via network models of panmictic demes linked by migration. However, it remains less clear how such systems would behave in more realistic population models where organisms move over a continuous landscape. Here, we use individual-based simulations to study the dynamics of several proposed underdominance systems in continuous-space. We find that all these systems can fail to persist in such environments, even after an initially successful establishment in the release area, confirming previous theoretical results from diffusion theory. At the same time, we find that a two-locus two-toxin-antidote system can invade connected demes through a narrow migration corridor. This suggests that the parameter space where underdominance systems can establish and persist in a release area while at the same time remaining confined to that area could be quite limited, depending on how a population is spatially structured. Overall, these results indicate that realistic spatial context must be considered when assessing strategies for the deployment of underdominance drives.

Mechanisms and patterns of magmatic fluid transport in cooling hydrous intrusions

Volatile outgassing from hydrous magma intrusions emplaced and cooling in the Earth's upper crust is key to a number of geologic processes including volcanic eruptions and ore deposition, yet the physical interactions between production, storage and transport of a magmatic volatile phase within magmatic intrusions and their large-scale thermal evolution have remained elusive. We performed numerical simulations of aqueous volatile transport in generic magma chambers as they crystallize in response to conductive and convective cooling and thereby transition from a crystal - volatile - melt suspension to a mush and eventually to a rigid rock. We used simplified but realistic material properties based on published phase equilibrium experiments, published grain-scale modeling results and general geological constraints.We found that the intrusion depth and water content exert decisive control on the rates and mechanisms of intrusion outgassing. Above a critical volatile content, highly permeable capillary tubes develop in crystal mush regions with intermediate crystal volume fractions (∼ 0.5 to 0.7), and such grain-scale tubes provide rapid intrusion-scale degassing paths. These tubes are located in a ring-like mush region inside the intrusion, allowing strongly lateral flow and focusing towards the top of the intrusion. If the water content of the magma is close to saturation at the time of emplacement (5 to 6 wt% H2O) and the depth of the magma chamber roof is at least 4 km deep, initially distributed breakthrough points may coalesce to a single area of fluid release. Large-scale intrusion geometry determines this location of focused fluid release, and cooling rate and size of the intrusion determine overall fluid flux. Feedbacks between local hydrofracturing and heat advection break up the focused fluid expulsion into many short-lived pulses. These conditions for large-scale fluid focusing favor the formation of porphyry copper deposits, but might also trigger caldera-forming ignimbrite eruptions.

Integrated grey-green management of avalanche risk: Economic and ecologic evidences from the Western Italian Alps

Avalanches represent one of the most common natural hazard in the Alps, and their risk mitigation is increasingly demanding for local administrations. The frequency of these events has also been influenced by the land use changes that affected the Alps in the past: from the over-exploitation of the first half of the XX century to the depopulation and natural reforestation of the last decades. In this study, we performed an economic and ecologic assessment of two alternative mitigation measures against avalanches: steel snow fences, the BAU scenario, and the combination of wooden snow fences gradually replaced by the protection forest, the Grey-Green Scenario. For both alternatives all costs sources that their implementation entails were evaluated, and the effects of the presence of fences on the natural forest regeneration was assessed. The results show how wooden fences are the most cost-effective solution to be placed in avalanche release areas below the treeline, due their high effectiveness coupled with lower construction costs compared to other types of measures, no dismantling costs and the contribution of the protective effect of the forest. Their adoption in the local risk management strategies, notwithstanding the shortcomings of the forest (e.g. fires, pests, …), could represent a reliable way to foster the implementation of ecosystem based disaster risk reduction solutions in mountain areas and meet the protection needs of the society in the most cost-effective way.

Unmonitored releases of small animals? The importance of considering natural dispersal, health, and human habituation when releasing a territorial mammal threatened by wildlife trade

Unmonitored release is a common practice, especially in small animals, that present a series of adverse conditions if not well-planned. Small research centers and non-governmental organizations in developing countries often receive animals that are then subject to unmonitored releases. We explored the patterns of post-release and natal dispersal in the Javan slow loris, a Critically Endangered venomous and territorial mammal that is highly threatened by wildlife trade. We then determined the importance of health status and human habituation for the survival of translocated and natally dispersing animals. We collected data from 2012 to 2018 on pre-release and pre-dispersal health conditions and human habituation, post-release and post-dispersal presence of wounds, behavior, and ranging patterns of 11 translocated and 11 natally dispersing individuals and compared them with 12 stable resident individuals. Translocated animals had a larger home range size (15.9 ± 4.1 ha) and higher wound presence during recaptures (0.47 ± 0.13) than stable resident individuals (3.2 ± 3.0 ha; 0.10 ± 0.06) but they did not differ from natally dispersing individuals (13.8 ± 3.7 ha; 0.28 ± 0.11). Both translocated and natally dispersing individuals can move to a different habitat type compared to their release area or natal range. The fate of both translocated and natally dispersing individuals was influenced by their health state (p < 0.001), and human habituation significantly affected the possibility of being captured for wildlife trade of translocated individuals (p = 0.048). We highlight the importance of considering natal dispersal, health state, and human habituation before the release of small animals to avoid death and capture for wildlife trade.

Potent and Broad but not Unselective Cleavage of Cytokines and Chemokines by Human Neutrophil Elastase and Proteinase 3.

In two recent studies we have shown that three of the most abundant human hematopoietic serine proteases—mast cell chymase, mast cell tryptase and neutrophil cathepsin G—show a highly selective cleavage of cytokines and chemokines with a strong preference for a few alarmins, including IL-18, TSLP and IL-33. To determine if this is a general pattern for many of the hematopoietic serine proteases we have analyzed the human neutrophil elastase (hNE) and human proteinase 3 (hPR-3) for their cleavage of a panel of 69 different human cytokines and chemokines. Our results showed that these two latter enzymes, in sharp contrast to the two previous, had a very potent and relatively unrestrictive cleavage on this panel of targets. Almost all of these proteins were cleaved and many of them were fully degraded. In light of the proteases abundance and their colocalization, it is likely that together they have a very potent degrading activity on almost any protein in the area of neutrophil activation and granule release, including both foreign bacterial or viral proteins as well as various self-proteins in the area of inflammation/infection. However, a few very interesting exceptions to this pattern were found indicating a high resistance to degradation of some cytokines and chemokines, including TNF-α, IL-5, M-CSF, Rantes, IL-8 and MCP-1. All of these are either important for monocyte-macrophage, neutrophil or eosinophil proliferation, recruitment and activation, suggesting that cytokines/chemokines and proteases may have coevolved to not block the recruitment of monocytes–macrophages, neutrophils and possibly eosinophils during an inflammatory response involving neutrophil activation.

Determining forest parameters for avalanche simulation using remote sensing data

Mountain forests offer effective, natural and cost-efficient protection against avalanches. Trees reduce the probability of an avalanche formation and can significantly decelerate small to medium size avalanches. Remote sensing methods enable an efficient assessment of forest structural parameters on large scale and therefore determine the protective capacity of a specific forest. The aims of this study are: (i) to evaluate the quality of forest structural parameters obtained from remote sensing data using two different methods; and (ii) to determine how forest parameters and forest cover changes influence avalanche runout. We compared the control assessment of maximum tree height and crown coverage in 107 plots (50 in evergreen and 57 in deciduous forests). The same parameters were analysed using (i) a photogrammetry-based vegetation height model (VHMP) and (ii) a LiDAR-based vegetation height model (VHML). The control assessment of surface roughness was compared to the analysis of a digital terrain model (DTM). We then simulated two avalanche case studies near Davos (Switzerland) with forest parameters estimated by the remote sensing and control methods. Tree height and crown coverage assessed with both remote sensing methods (VHMP and VHML) did not differ significantly from the control measurements. However, surface roughness was underestimated. This had a significant influence on simulation results. For the first case study, a wet-snow avalanche, the simulated runout distances did not differ significantly, when using forest parameters from either of the two tested remote sensing methods. The simulated runout distance increased for an avalanche scenario with less forest cover in the release area and/or less forest cover after forest destruction by a preceding avalanche event. For the second case study, a dry-snow avalanche, the forest cover was underestimated by the VHMP, which led to longer simulated runout distances. Our study indicates that available remote sensing methods are increasingly suitable for the determination of forest parameters which are relevant for avalanche simulation models. However, more research is needed on the precise estimation of forest cover in release areas and understanding how forest cover changes affect avalanche runout.

Assessing the health risks of reintroduction: The example of the Amur leopard, Panthera pardus orientalis.

Translocation of wildlife as a means of reintroducing or reinforcing threatened populations is an important conservation tool but carries health risks for the translocated animals and their progeny, as well as wildlife, domestic animals and humans in the release area. Disease risk analyses (DRA) are used to identify, prioritize and design mitigation strategies to address these threats. Here, we use a DRA undertaken for Amur leopards (Panthera pardus orientalis) to illustrate how specific methodology can optimize mitigation strategy design. A literature review identified a total of 98 infectious hazards and 28 non-infectious hazards. Separate analyses were undertaken for disease risks in leopards from hazards of source origin (captive zoo collections and the transit pathway to the Russian Far East), or of destination origin (in breeding enclosures and wider release areas); and for disease risks in other wildlife, domesticated species or humans, similarly from hazards of source or destination origin. Hazards were assessed and ranked as priority 1, priority 2, priority 3 or low priority in each of the defined scenarios. In addition, we undertook a generic assessment of stress on individual leopards. We use three examples to illustrate the process: Chlamydophila felis, canine distemper virus (CDV) and feline immunodeficiency virus (FIV). We found that many potentially expensive screening procedures could be performed prior to export of leopards, putting the onus of responsibility onto the zoo sector, for which access to diagnostic testing facilities is likely to be optimal. We discuss how our methods highlighted significant data gaps relating to pathogen prevalence in the RussianFarEast and likely future unpredictability, in particular with respect to CDV. There was emphasis at all stages on record keeping, meticulous planning, design, staff training and enclosure management, which are relatively financially inexpensive. Actions to minimize stress featured at all time points in the strategy and also focussed on planning, design and management.

Simulation of Glacial Avalanche Hazards in Shyok Basin of Upper Indus

Glacial avalanche hazards can threaten lives and damage infrastructures in high altitude mountainous regions. In April 2012 a gigantic ice plus rock avalanche destroyed military camp at Gyari and killed 139 persons. Antecedent, the objectives of this study are to simulate and model Gyari camp glacial avalanche with reference to its extent, height, momentum, velocity and pressure and, to simulate and model the other potential glacial avalanche prone areas in Shyok basin. To simulate the Gyari camp glacial hazard and other potential glacial avalanche hazards, an empirical process based Glacier Avalanche Model; Rapid Access Mass Movement Simulation (RAMMS) is used. The RAMMS model encompasses the variables like avalanche release height and release area for the conduct of simulation. The model output of Gyari glacial avalanche hazard resulted from a max pressure of 2500 KPa, max velocity of 90 m/s, and the max flow height of 40 m, while the resulted output debris volume calculated was 4.3145 million m3. The calibrated agreement was found in extent and height of actual debris in comparison with RAMMS simulated output. The potential hazardous glacial avalanche prone areas of Shyok basin were simulated by RAMMS model after the model being calibrated to the actual incident of Gyari. The study has resulted in identifying the Siachen glacier conflict zone being more prone to avalanche hazards because of host factors in general and the anthropogenic factor in particular.

Mapping the spatial variability of the field distribution of sterile Anastrepha ludens over a release area

AbstractThe sterile insect technique (SIT) is an environmental‐friendly method used against Anastrepha ludens Loew (Diptera: Tephritidae) populations. This study aimed to perform an analysis of the spatial variability of the field distribution of sterile A. ludens using a geostatistical approach along with Geographic Information Systems (GIS). Field data on captures of sterile A. ludens during a Valencia orange season over a release area were analysed using spherical, exponential and Gaussian variograms. Such variograms were evaluated by criteria such as the mean absolute error, average standard error, root mean square error and the coefficient of determination. Results revealed a spatially structured distribution of sterile A. ludens across the release area. Interpolated models by Ordinary Kriging technique exhibited continuous surfaces evidencing spatial heterogeneity of the distribution of flies. Such a result evidenced that the spatial dynamics of flies significantly varied despite the planned uniform coverage of the release. The GIS led to integrating spatial information of the spatial dynamics through one single model. The release activity should be improved westward of the studied area, as the final model suggested that the ratio sterile: wild is lower than that in the east. This study provides insights into the spatial analysis of the distribution of sterile flies further than one single geographical point. Moreover, it highlights geostatistical techniques and GIS as useful tools for the assessment of the impact and quality of the release activity over fruit‐growing areas subjected to an area‐wide integrated pest management approach.

Wild Steps in a semi-wild setting? Habitat selection and behavior of European bison reintroduced to an enclosure in an anthropogenic landscape.

Recently, several wild or semi-wild herds of European bison have been reintroduced across Europe. It is essential for future successful bison reintroductions to know how the European bison use different habitats, which environmental parameters drive their habitat selection, and whether their habitat use and behavioural patterns in new reintroduction sites differ from habitats where European bison have been roaming freely for a long time. Here, we address these questions for a 40-ha enclosed site that has been inhabited by semi-free ranging European bison since 2012. The site, Vorup Meadows, is adjacent to the Gudenå river in Denmark and consists of human-modified riparian meadows. During 2013 we monitored the behavioural pattern and spatial use of the 11 bison present and in parallel carried out floristic analyses to assess habitat structure and food quality in the enclosure. We tested habitat use and selection against environmental parameters such as habitat characteristics, plant community traits, topography, and management area (release area vs. meadow area) using linear regression and spatial models. The bison herd had comparable diurnal activity patterns as observed in previous studies on free-roaming bison herds. Topography emerged as the main predictor of the frequency of occurrence in our spatial models, with high-lying drier areas being used more. Bison did not prefer open areas over areas with tree cover when accounting for habitat availability. However, they spent significantly more time in the release area, a former agricultural field with supplementary fodder, than expected from availability compared to the rest of the enclosure, a meadow with tree patches. We wish to increase awareness of possible long-term ethological effects of the release site and the management protocols accomplished here that might reduce the ecological impact by the bison in the target habitat, and thereby compromise or even oppose the conservation goals of the conservation efforts.

Mapping landslide release area using Random Forest Model

Landslides pose threats not only to infrastructure around the world but also to local communities. One particularly susceptible area in Taiwan is in the Zhoukou River basin, Kaoping watershed. Landslides source area plays an important role in landslide occurrence, where the triggering stage initiates the failure. The conditions of landslide source area are assumed to be the same in the future. This study aimed to produce a Random Forest model that accurately predicts future landslide release in this area by validating the predictions against those observed landslide releases in this region. The landslide data were recorded in the year of 2010, a year after typhoon Morakot stroked Taiwan in 2009, triggering huge number of landslides all over the country. This study proposed the new concept to separate landslides area into release as its original source and focuses on using the topographical factors derived from Digital Elevation Model (DEM) as the independent variable in predicting landslides occurrence, including Slope, Aspect, Curvature, Topographic Wetness Index, Average Slope and Distance from the river, and an additional geological map of the study area.An observed landslide release occurrence layer posed as the dependent variable classifier in the model. First, data sampling strategies applied show an optimal model to be created with the highest Area Under Curve (AUC) value of 0.814. Next, this model identified the most influential factors causing landslides. Aspect, were determined as being most influential factor, where Distance from river, and Slope as second and third most influential.The concept of release area separation showed a better AUC value model compared to the model using conventional full landslide inventory. The random forest model also showed a reliable result when compared to logistic regression and decision tree using the same data sampling, with the AUC value of 0.814, 0.65, and 0.728 respectively. The results have proven that random forest model is suitable for producing landslide release susceptibility map.

Locally Fixed Alleles: A method to localize gene drive to island populations

Invasive species pose a major threat to biodiversity on islands. While successes have been achieved using traditional removal methods, such as toxicants aimed at rodents, these approaches have limitations and various off-target effects on island ecosystems. Gene drive technologies designed to eliminate a population provide an alternative approach, but the potential for drive-bearing individuals to escape from the target release area and impact populations elsewhere is a major concern. Here we propose the “Locally Fixed Alleles” approach as a novel means for localizing elimination by a drive to an island population that exhibits significant genetic isolation from neighboring populations. Our approach is based on the assumption that in small island populations of rodents, genetic drift will lead to alleles at multiple genomic loci becoming fixed. In contrast, multiple alleles are likely to be maintained in larger populations on mainlands. Utilizing the high degree of genetic specificity achievable using homing drives, for example based on the CRISPR/Cas9 system, our approach aims at employing one or more locally fixed alleles as the target for a gene drive on a particular island. Using mathematical modeling, we explore the feasibility of this approach and the degree of localization that can be achieved. We show that across a wide range of parameter values, escape of the drive to a neighboring population in which the target allele is not fixed will at most lead to modest transient suppression of the non-target population. While the main focus of this paper is on elimination of a rodent pest from an island, we also discuss the utility of the locally fixed allele approach for the goals of population suppression or population replacement. Our analysis also provides a threshold condition for the ability of a gene drive to invade a partially resistant population.

Seismic location and tracking of snow avalanches and slush flows on Mt. Fuji, Japan

Abstract. Avalanches are often released at the dormant stratovolcano Mt. Fuji, which is the highest mountain of Japan (3776 m a.s.l.). These avalanches exhibit different flow types from dry-snow avalanches in winter to slush flows triggered by heavy rainfall in late winter to early spring. Avalanches from different flanks represent a major natural hazard as they can reach large dimensions with run-out distances up to 4 km, destroy parts of the forest, and sometimes damage infrastructure. To monitor the volcanic activity of Mt. Fuji, a permanent and dense seismic network is installed around the volcano. The small distance between the seismic sensors and the volcano flank (&lt;10 km) allowed us to detect numerous avalanche events from the seismic recordings and locate them in time and space. We present the detailed analysis of three avalanche or slush flow periods in the winters of 2014, 2016, and 2018. The largest events (size class 4–5) are detected by the seismic network at maximum distances of about 15 km, and medium-size events (size class 3–4) within a radius of 9 km. To localize the seismic events, we used the automated approach of amplitude source location (ASL) based on the decay of the seismic amplitudes with distance from the moving flow. The recorded amplitudes at each station have to be corrected by the site amplification factors, which are estimated by the coda method using data from local earthquakes. Our results show the feasibility of tracking the flow path of avalanches and slush flows with considerable precision (on the order of magnitude of 100 m) and thus estimating information such as the approximate run-out distance and the average front speed of the flows, which are usually poorly known. To estimate the precision of the seismic tracking, we analyzed aerial photos of the release area and determined the flow path and run-out distance, estimated the release volume from the meteorological records, and conducted numerical simulations with Titan2D to reconstruct the dynamics of the flow. The precision as a function of time is deduced from the comparison with the numerical simulations, showing mean location errors ranging between 85 and 271 m. The average front speeds estimated seismically, which ranged from 27 to 51 m s−1, are consistent with the numerically predicted speeds. In addition, we deduced two scaling relationships based on seismic parameters to quantify the size of the mass flow events. Our results are indispensable for assessing avalanche risk in the Mt. Fuji region as seismic records are often the only available dataset for this natural hazard. The approach presented here could be applied in the development of an early-detection and location system for avalanches based on seismic sensors.

Mutual Dynamics of Heat Dissipation and Oil Displacement Fronts during In-Situ Oil Combustion. One-Dimensional Simulation

One-dimensional axis-symmetrical and plane-symmetrical problem of propagation of the combustion and displacement fronts in oil-containing layer in situ has been considered numerically. Two combustible components, viz. liquid (oil) and solid (kerogen, oil sorbate), were considered. The influence of the blast rate, liquid component viscosity, oxygen concentration in blasted air and heat losses (the width of the oil-containing layer) on the dynamics of the heat dissipation and displacement fronts is investigated. In the cylindrical system the oxidizer flow to the combustion front is reducing over time; and the shift-down of the maximum temperature from the solid combustion front to the oil displacement front takes place (the combustion front “jump”). The time of the “jump” may vary from tenths to hundreds of days and the distance of the shift, – up to 10 or more meters, depending on the parameters of the system. After the “jump”, the combustion rate and maximum temperature continue to deteriorate and after the period of time close to the time lapse before the “jump” the chemical reaction ceases. Herewith the transition of combustion to the liquid phase after the “jump” doesn’t influence notably on oils displacement front speed. The time of the “jump”, as well as the velocity of the mutual combustion (maximum temperature) front and displacement front removal nearly linearly depends on incoming gas blast rate and non-linearly – on oil viscosity. When viscosity is low, the displacement front rapidly runs away from the combustion front, time of the “jump” retards and the distance between the fronts at the instance of the “jump” may reach 10 m or more. The oxygen concentration in the gas being blasted influences significantly on the mutual dynamics of the combustion and displacement fronts since combustion front velocity is proportional to oxygen concentration and displacement front velocity is independent on it. Oxygen enrichment of the gas being blasted just after the “jump” may help localize the area of heat release (combustion) near the oil displacement front. The mentioned manipulation may be utilized for sustainability control of the displacement front. However for its practical implementation it is necessary to have information on concentration and temperature fields inside the layer, which may be obtained from indirect data and via modeling. The results of investigation may be utilized for development of technical projects of oil recovery via in-situ combustion.