The utilisation of geothermal energy in the Netherlands is primarily focused on deep sedimentary aquifers, which are often intersected by major faults. Geothermal operations (i.e. fluid production and injection) may alter the effective stress state along these faults and trigger induced seismic events. Pore pressure perturbations have been generally considered the main driver of injection-induced seismicity. However, thermal stresses caused by temperature gradients between the re-injected cold fluid and the reservoir rock may also contribute to the triggering of earthquakes in geothermal reservoirs. While existing geothermal power plants operating in sandstone reservoirs did not produce any major induced seismicity, it is a matter of debate whether a reduction in the temperature of the re-injected fluid could increase the seismic hazard potential. In this study, we applied modified Gutenberg–Richter statistics based on frictional Coulomb stress variations implemented in a coupled thermo-hydro-mechanical model to estimate the seismic hazard caused by the operation of a geothermal doublet. We conducted a systematic parametric study to assess and rank the impact of different intrinsic (geological) and extrinsic (operational) parameters on the induced seismic hazard potential. We identified a competing mechanism between induced variations in pore pressure and thermal stress within the reservoir in controlling induced seismicity. We found that stress changes induced by pore pressure variations are the main cause of seismic hazard, although thermally induced stresses also contribute significantly. The results indicate that by optimising the operational parameters it is possible to increase production efficiency while maintaining a long-term control over the fluid injection-induced seismicity.

Bedrock overdeepenings exposed by continued glacial retreat can store precipitation and meltwater, potentially leading to the formation of new proglacial lakes. These lakes may pose threats of glacial lake outburst floods (GLOFs) in high mountain areas, particularly if new lakes form in geomorphological setups prone to triggering events such as landslides or moraine collapses. We present the first complete inventory for future glacial lakes in High Mountain Asia by computing the subglacial bedrock for ~100 000 glaciers and estimating overdeepening area, volume and impact hazard for the larger potential lakes. We detect 25 285 overdeepenings larger than 104 m2 with a volume of 99.1 ± 28.6 km3 covering an area of 2683 ± 773.8 km2. For the 2700 overdeepenings larger than 105 m2, we assess the lake predisposition for mass-movement impacts that could trigger a GLOF by estimating the hazard of material detaching from surrounding slopes. Our findings indicate a shift in lake area, volume and GLOF hazard from the southwestern Himalayan region toward the Karakoram. The results of this study can be used for anticipating emerging threats and potentials connected to glacial lakes and as a basis for further studies at suspected GLOF hazard hotspots.

Earthquakes associated with gas production have been recorded in the northern part of the Netherlands since 1986. The Huizinge earthquake of 16 August 2012, the strongest so far with a magnitude of ML = 3.6, prompted reassessment of the seismicity induced by production from the Groningen gas field. An international research programme was initiated, with the participation of many Dutch and international universities, knowledge institutes and recognised experts.

The prime aim of the programme was to assess the hazard and risk resulting from the induced seismicity. Classic probabilistic seismic hazard and risk assessment (PSHA) was implemented using a Monte Carlo method. The scope of the research programme extended from the cause (production of gas from the underground reservoir) to the effects (risk to people and damage to buildings). Data acquisition through field measurements and laboratory experiments was a substantial element of the research programme. The existing geophone and accelerometer monitoring network was extended, a new network of accelerometers in building foundations was installed, geophones were placed at reservoir level in deep wells, GPS stations were installed and a gravity survey was conducted.

Results of the probabilistic seismic hazard and risk assessment have been published in production plans submitted to the Minister of Economic Affairs, Winningsplan Groningen 2013 and 2016 and several intermediate updates. The studies and data acquisition further constrained the uncertainties and resulted in a reduction of the initially assessed hazard and risk.

Adulticides applied against mosquitoes can reduce vector populations during times of high arbovirus transmission. However, impacts of these insecticides on pollinators and other non-target organisms are of concern to mosquito control professionals, beekeepers and others. We evaluated mortality of Culex quinquefasciatus and Apis mellifera when caged insects were exposed to low and high label rates of four common adulticides (Aqua-Pursuit™ [permethrin], Duet® [prallethrin + sumithrin], Fyfanon® [malathion] and Scourge® [resmethrin]) at six distances up to 91.4 m from a truck-mounted ultra-low-volume sprayer. Honey bee mortality was both absolutely low (<10%) and low relative to mosquito mortality for most products, distances, and application rates. Exceptions were at the high rate of Fyfanon (honey bee mortality of 22–100% at distances ≤61 m) and the low rate of Scourge (mortality <10% for both insects). The greatest ratios of mosquito-to-honey bee mortality were found for the low rate of Fyfanon (30× greater) and the high rate of Duet (50× greater). Aqua-Pursuit and Fyfanon tended to increase mortality of both species at closer distances and at higher application rate; this was related to increased number and size of spray droplets. Wind speed and temperature had inconsistent effects on mortality of mosquitoes only. In this bioassay designed to have insects directly intercept insecticide droplets, mosquito adulticides applied at low rates and at >61 m had limited impacts on honey bee mortality while providing effective mosquito control.

A simulation study was conducted in order to investigate the influence of vortex deformation on wake encounter characteristics. Wake vortices tend to be strongly deformed during the decay process, depending on the atmospheric conditions in terms of turbulence and thermal stratification. For quantification of the influence of vortex deformation, encounters of an aircraft of the ‘Medium’ category behind a generator aircraft of the ‘Heavy’ category were simulated with straight vortices and with realistically deformed vortices derived from large-eddy simulations. All relevant parameters that influence the encounter characteristics, such as encounter angles and positions, were varied within a wide range. In order to cover all kinds of vortex deformation, encounters with different vortex ages from 16-136 seconds were simulated. Hence, all relevant phases during the vortex decay from nearly straight and wavy vortices to vortex rings were considered.

The parameter variation study revealed that on average the impact on the encountering aircraft is less with deformed vortices than with straight vortices of comparable strength. Especially with vortex rings, the encountering aircraft is exposed to a much smaller impact. However, the results also show a larger aircraft response during encounters with wavy vortices just prior to vortex linking. The maximum aircraft response with wavy vortices is stronger than with straight vortices of comparable strength. Also, the strongest encounters occur under greater encounter angles with deformed vortices than with straight ones.

Rural depopulation has different effects on biodiversity and ecosystems in many regions of the world. For large carnivores such as pumas (Puma concolor) the effects are uncertain. An analysis of relationships between patterns of rural depopulation and perceptions of the risk posed by pumas among Aymara people in the altiplano region of Chile examined perceived risk, as well as self-reported losses, in relation to livestock husbandry, sociodemographic variables (age, household size, and residency status), and reported self-sufficiency. There was no evidence that rural depopulation elevated perceived risk, or the level of self-reported losses of livestock blamed on pumas. Indeed, many respondents, including older respondents and those with smaller households, reported a decline in perceived risk over the preceding five years. These perceptions of risk were not associated with self-reported losses to pumas in the previous year. An increase in perceived risk was associated with the use of guards for livestock, suggesting livestock owners accommodated their absences from herds by using guards. Absolute numbers of livestock lost increased with the distance from households to where livestock were grazed or gave birth. A cost-effective verification system for puma attacks is recommended, and further human dimensions research is required to identify the owners who complained and the costs and benefits of different wildlife species. Further interventions to prevent either livestock losses or retaliation against pumas can then be targeted more precisely.