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  • 1
    Publication Date: 2023-06-19
    Description: GIS-based multicriteria evaluation (MCE) provides a framework for analysing complex decision problems by quantifying variables of interest to score potential locations according to their suitability. In the context of earthquake preparedness and post-disaster response, MCE has relied mainly on uninformed or non-expert stakeholders to identify high-risk zones, prioritise areas for response, or highlight vulnerable populations. In this study, we compare uninformed, informed non-expert, and expert stakeholders’ responses in MCE modelling for earthquake response planning in Vancouver, Canada. Using medium- to low-complexity MCE models, we highlight similarities and differences in the importance of infrastructural and socioeconomic variables, emergency services, and liquefaction potential between a non-weighted MCE, a medium-complexity informed non-expert MCE, and a low-complexity MCE informed by 35 local earthquake planning and response experts from governmental and non-governmental organisations. Differences in the observed results underscore the importance of accessible, expert-informed approaches for prioritising locations for earthquake response planning and for the efficient and geographically precise allocation of resources.
    Description: Friedrich-Alexander-Universität Erlangen-Nürnberg (1041)
    Keywords: ddc:551.22 ; Multicriteria evaluation ; Earthquake ; Disaster response ; Natural hazards ; Expert knowledge ; Participatory mapping
    Language: English
    Type: doc-type:article
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  • 2
    Publication Date: 2022-10-05
    Description: The spatial and angular emission patterns of artificial and natural light emitted, scattered, and reflected from the Earth at night are far more complex than those for scattered and reflected solar radiation during daytime. In this commentary, we use examples to show that there is additional information contained in the angular distribution of emitted light. We argue that this information could be used to improve existing remote sensing retrievals based on night lights, and in some cases could make entirely new remote sensing analyses possible. This work will be challenging, so we hope this article will encourage researchers and funding agencies to pursue further study of how multi‐angle views can be analyzed or acquired.
    Description: Plain Language Summary: When satellites take images of Earth, they usually do so from directly above (or as close to it as is reasonably possible). In this comment, we show that for studies that use imagery of Earth at night, it may be beneficial to take several images of the same area at different angles within a short period of time. For example, different types of lights shine in different directions (street lights usually shine down, while video advertisements shine sideways), and tall buildings can block the view of a street from some viewing angles. Additionally, since views from different directions pass through different amounts of air, imagery at multiple angles could be used to obtain information about Earth's atmosphere, and measure artificial and natural night sky brightness. The main point of the paper is to encourage researchers, funding agencies, and space agencies to think about what new possibilities could be achieved in the future with views of night lights at different angles.
    Description: Key Points: Remote sensing using the visible band at night is more complex than during the daytime, especially due to the variety of artificial lights. Views of night lights intentionally taken from multiple angles provide several advantages over near‐nadir or circumstantial view geometries. Night lights remote sensing would benefit from greater consideration of the role viewing geometry plays in the observed radiance.
    Description: EC H2020 H2020 Societal Challenges http://dx.doi.org/10.13039/100010676
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: Slovak Research and Development Agency
    Description: Xunta de Galicia (Regional Government of Galicia) http://dx.doi.org/10.13039/501100010801
    Description: National Aeronautics and Space Administration http://dx.doi.org/10.13039/100000104
    Description: University of Hong Kong http://dx.doi.org/10.13039/501100003803
    Description: Fonds de recherche du Québec
    Description: EC Emprego, Assuntos Sociais e Inclusão European Social Fund http://dx.doi.org/10.13039/501100004895
    Description: Natural Environment Research Council http://dx.doi.org/10.13039/501100000270
    Description: City of Cologne, Germany
    Keywords: ddc:551.5
    Language: English
    Type: doc-type:article
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  • 3
    Publication Date: 1989-05-26
    Description: The eye needs to biosynthesize 11-cis-retinoids because the chromophore of rhodopsin is 11-cis-retinal. The critical metabolic step is the endergonic isomerization of free all-trans-retinol (vitamin A) into 11-cis-retinol. This isomerization process can take place in isolated membranes from the retinal pigment epithelium in the absence of added energy sources. Specific binding proteins probably do not serve as an energy source, and since all of the reactions in the visual cycle are shown here to be reversible, trapping reactions also do not participate in the isomerization reaction. One previously unexplored possibility is that the chemical energy in the bonds of the membrane itself may drive the isomerization reaction. A group transfer reaction is proposed that forms a retinyl ester from a lipid acyl donor and vitamin A. This transfer can drive the isomerization reaction because the all-trans-retinyl ester is isomerized directly to 11-cis-retinol. Thus, the free energy of hydrolysis of the ester is coupled to the thermodynamically uphill trans to cis isomerization. The prediction of an obligate C-O bond cleavage in the vitamin A moiety during isomerization is borne out. Although the natural substrate for isomerization is not known, all-trans-retinyl palmitate is processed in vitro to 11-cis-retinol by pigment epithelial membranes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Deigner, P S -- Law, W C -- Canada, F J -- Rando, R R -- EY04096/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 1989 May 26;244(4907):968-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2727688" target="_blank"〉PubMed〈/a〉
    Keywords: Amphibians ; Animals ; Cattle ; Cell Membrane/*metabolism ; *Energy Metabolism ; Isomerases/metabolism ; Isomerism ; Kinetics ; Molecular Structure ; Pigment Epithelium of Eye/*metabolism/radiation effects ; Ultraviolet Rays ; Vitamin A/analogs & derivatives/*metabolism ; *cis-trans-Isomerases
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2022-11-26
    Description: We investigate induced seismicity associated with a hydraulic stimulation campaign performed in 2020 in the 5.8 km deep geothermal OTN‐2 well near Helsinki, Finland as part of the St1 Deep Heat project. A total of 2,875 m3 of fresh water was injected during 16 days at well‐head pressures 〈70 MPa and with flow rates between 400 and 1,000 L/min. The seismicity was monitored using a high‐resolution seismic network composed of 10 borehole geophones surrounding the project site and a borehole array of 10 geophones located in adjacent OTN‐3 well. A total of 6,121 induced earthquakes with local magnitudes MLHel〉−1.9 ${M}_{\mathrm{L}}^{\mathrm{H}\mathrm{e}\mathrm{l}} 〉 -1.9$ were recorded during and after the stimulation campaign. The analyzed statistical parameters include magnitude‐frequency b‐value, interevent time and interevent time ratio, as well as magnitude correlations. We find that the b‐value remained stationary for the entire injection period suggesting limited stress build‐up or limited fracture network coalescence in the reservoir. The seismicity during the stimulation neither shows signatures of magnitude correlations, nor temporal clustering or anticlustering beyond those arising from varying injection rates. The interevent time statistics are characterized by a Poissonian time‐varying distribution. The calculated parameters indicate no earthquake interaction. Focal mechanisms suggest that the injection activated a spatially distributed network of similarly oriented fractures. The seismicity displays stable behavior with no signatures pointing toward a runaway event. The cumulative seismic moment is proportional to the cumulative hydraulic energy and the maximum magnitude is controlled by injection rate. The performed study provides a base for implementation of time‐dependent probabilistic seismic hazard assessment for the project site.
    Description: Plain Language Summary: We investigate anthropogenic seismicity associated with fluid injection into the 5.8 km deep geothermal OTN‐2 well near Helsinki, Finland, as a part of St1 Deep Heat Project. A total of 2,875 m3 of fresh water was injected during 16 days at well‐head pressures 〈70 MPa and with flow rates between 400 and 1,000 L/min. The seismicity was monitored using a seismic network composed of 20 borehole geophones located in Helsinki area and in the OTN‐3 well located close by the injection site. A total of 6,121 earthquakes indicating fractures of 1–30 m size were recorded during and after stimulation campaign. Using a handful of statistical properties derived from earthquake catalog we found no indication for earthquakes being triggered by other earthquakes. Instead, the earthquake activity rates, as well as the maximum earthquake size stayed proportional to the fluid injection rate. The spatio‐temporal behavior of seismicity and its properties suggest earthquakes occurred not on a single fault, but in a distributed network of similarly oriented fractures, limiting the possibility for occurrence of violent earthquakes. The performed study provides evidence that the induced seismicity due to injection performed within St1 Deep Heat project is stable and allow to constrain seismic hazard.
    Description: Key Points: Induced seismicity associated with stimulation campaign in a 5.8 km deep geothermal OTN‐2 well passively responds to injection operations. Seismicity is a non‐stationary Poisson process with seismicity rate and maximum magnitude modulated by the hydraulic energy input rate. Seismicity clusters in space and time in response to fluid injection but no interaction between earthquakes is observed.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: https://doi.org/10.5880/GFZ.4.2.2022.001
    Keywords: ddc:551.22 ; induced seismicity ; hydraulic stimulation ; earthquake clustering ; earthquake interactions ; Poissonian distribution ; magnitude correlations ; interevent times
    Language: English
    Type: doc-type:article
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  • 5
    Publication Date: 2024-02-15
    Description: Hydraulic fracturing (HF) operations are widely associated with induced seismicity in the Western Canadian Sedimentary Basin. This study correlates injection parameters of 12,903 HF stages in the Kiskatinaw area in northeast British Columbia with an enhanced catalog containing 40,046 earthquakes using a supervised machine learning approach. It identifies relevant combinations of geological and operational parameters related to individual HF stages in efforts to decipher fault activation mechanisms. Our results suggest that stages targeting specific geological units (here, the Lower Montney formation) are more likely to induce an earthquake. Additional parameters positively correlated with earthquake likelihood include target formation thickness, injection volume, and completion date. Furthermore, the COVID‐19 lockdown may have reduced the potential cumulative effect of HF operations. Our results demonstrate the value of machine learning approaches for implementation as guidance tools that help facilitate safe development of unconventional energy technologies.
    Description: Plain Language Summary: Hydraulic fracturing (HF), a technique used in unconventional energy production, increases rock permeability to enhance fluid movement. Its use has led to an unprecedented increase of associated earthquakes in the Western Canadian Sedimentary Basin in the last decade, among other regions. Numerous studies have investigated the relationship between induced earthquakes and HF operations, but the connection between specific geological and operational parameters and earthquake occurrence is only partly understood. Here, we use a supervised machine learning approach with publicly available injection data from the British Columbia Oil and Gas Commission to identify influential HF parameters for increasing the likelihood of a specific operation inducing an earthquake. We find that geological parameters, such as the target formation and its thickness, are most influential. A small number of operational parameters are also important, such as the injected fluid volume and the operation date. Our findings demonstrate an approach with the potential to develop tools to help enable the continued development of alternative energy technology. They also emphasize the need for public access to operational data to estimate and reduce the hazard and associated risk of induced seismicity.
    Description: Key Points: We use supervised machine learning to investigate the relationship between hydraulic fracturing operation parameters and induced seismicity. Geological properties and a limited number of operational parameters predominantly influence the probability of an induced earthquake. The approach has the potential to guide detailed investigations of injection parameters critical for inducing earthquakes.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Gouvernement du Canada Natural Sciences and Engineering Research Council of Canada http://dx.doi.org/10.13039/501100000038
    Description: https://doi.org/10.5281/zenodo.5501399
    Description: https://ds.iris.edu/gmap/XL
    Description: https://files.bcogc.ca/thinclient/
    Description: https://open.canada.ca/data/en/dataset/7f245e4d-76c2-4caa-951a-45d1d2051333
    Description: https://github.com/obspy/obspy
    Description: https://github.com/eqcorrscan/EQcorrscan
    Description: https://github.com/smousavi05/EQTransformer
    Description: https://github.com/Dal-mzhang/REAL
    Description: https://scikit-learn.org/stable/
    Description: https://docs.fast.ai/
    Description: https://xgboost.readthedocs.io/en/stable/
    Description: https://github.com/slundberg/shap
    Description: https://docs.generic-mapping-tools.org/latest/
    Keywords: ddc:551.22 ; induced seismicity ; machine learning ; hydraulic fracturing
    Language: English
    Type: doc-type:article
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  • 6
    Publication Date: 2024-02-09
    Description: When exposed to sufficiently humid environments, pollen grains burst and release large quantities of small subpollen particles (SPPs) which carry ice nucleating macromolecules. In this study, for the first time we develop a physically based parameterization describing the bursting process of pollen by applying a turgor pressure parameterization and quantify the impact SPPs have on overall ice nucleation in clouds. SPPs are generated from simulated birch pollen emissions over Europe for a 10‐day case study in spring. We found SPP concentrations to surpass pollen grain concentrations by 4–6 orders of magnitude leading to an abundance of biological ice nuclei from SPPs in the range of 103−104 m−3. However, it is found that these concentrations lead to only small changes in hydrometeor number densities and precipitation. Addressing the question when SPPs become relevant for ice nucleation in clouds, we conducted a sensitivity investigation. We find that amplifying ice nucleation efficiency of biological particles by factors greater 100 increases the ice particle numbers by up to 25% (T ≈ 268 K). Strong reductions show in cloud droplet number concentration and water vapor at these temperatures while water vapor is increasing at 600 m. Overall, we found a net reduction of water in the atmosphere as liquid and particularly water vapor density is reduced, while frozen water mass density increases above 257 K. Findings indicate an alteration of mixed‐phase cloud composition and increased precipitation (up to 6.2%) when SPPs are considered as highly efficient biological ice nuclei.
    Description: Key Points Subpollen particles (SPPs) reach freezing altitudes in large number concentrations. Nucleation efficiency of SPPs affects both amplitude and sign of impact on nucleation processes. Relevant impact requires greatly increased nucleation efficiency of the SPPs.
    Description: H2020 European Research Council http://dx.doi.org/10.13039/100010663
    Description: University of Toronto Scarborough Department of Physical and Environmental Sciences Travel Award
    Description: Ministry of Science, Research and the Arts Baden‐Württemberg
    Description: Deutsche Forschungsgemeinschaft
    Description: https://doi.org/10.35097/830
    Keywords: ddc:551.5 ; subpollen particle ; SPP ; biological ice nucleation ; burst parameterization
    Language: English
    Type: doc-type:article
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  • 7
    Publication Date: 2023-11-27
    Description: Gravity waves (GWs) are generated at all altitudes in the atmosphere, but sources above the lower stratosphere are rarely considered by parameterizations employed in general circulation models. This study assesses the potential impact on the thermosphere produced by small‐scale waves originating at different heights. Within the proposed numerical framework, GW sources are represented by wave momentum forcing, whose values are expressed relative to the forcing required to obtain typical wave spectra around the tropopause. The relative importance of tropospheric and extra‐tropospheric sources and the response in the thermosphere are studied in a series of sensitivity experiments. They demonstrate that the accumulation of wave momentum steeply drops with height as a consequence of decreasing density, even when the forcing is maintained at a uniform level throughout the middle atmosphere. When a broad spectrum is forced at twice the tropospheric rate, the thermospheric drag is increased by only a factor of two, and that increase is produced by waves that were forced in the lower stratosphere. With increasing altitude, vertically localized sources contribute progressively less. For example, for GWs excited near the mesopause to produce an impact comparable with that due to waves propagating from below, the forcing must be orders of magnitude stronger than in the troposphere. The estimated forcing of the so‐called secondary harmonics by breaking primary waves is much weaker, such that the systematic dynamical effect of secondary waves in the thermosphere is negligible compared to that of the primary GWs generated in the troposphere.
    Description: Plain Language Summary: Multiple observations demonstrate that gravity waves (GWs) are generated at all atmospheric levels, however numerical general circulation models employing parameterizations that account for wave sources only in the troposphere are able to reproduce the state and dynamics of the middle and upper atmosphere reasonably well. Assessing the role of GWs generated above the troposphere is extremely challenging, because such waves are difficult to separate from those of tropospheric origin in observations. The mechanisms of wave generation in the middle atmosphere are very complex and not fully understood. We developed a numerical framework, in which the strength of the extra‐tropospheric sources is represented by multiples of those in the troposphere. In the series of sensitivity tests, we demonstrate that the contribution of sources to the total wave momentum drops with height following the density decrease, and that the tropospheric sources capture the major part of the total momentum and of the associated GW drag in the thermosphere. One of the conclusions of this study is that the impact in the thermosphere of secondary waves, which are believed to be excited near the mesopause, is negligible compared to that of primary waves propagating from the troposphere.
    Description: Key Points: A framework for assessing impacts of gravity waves generated by sources distributed over all heights in the middle atmosphere is developed. The thermospheric response to sources above the tropopause is primarily produced by waves generated in the lower. stratosphere Localized sources produce negligible thermospheric drag unless the forcing is orders of magnitude stronger than in the troposphere.
    Description: Earth Sciences Division http://dx.doi.org/10.13039/100014573
    Description: https://kauai.ccmc.gsfc.nasa.gov/instantrun/hwm
    Description: https://ccmc.gsfc.nasa.gov/modelweb/models/nrlmsise00.php
    Keywords: ddc:551.5 ; gravity waves ; wave sources ; thermosphere ; secondary waves ; middle atmosphere
    Language: English
    Type: doc-type:article
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