Making seismology accessible to the public in Nepal: an earthquake location tutorial for education purposes

Earthquakes become a hot topic for discussion in Nepali communities when a big local event happens. Beyond the seismic monitoring and research, efforts to improve the population’s preparedness or to reduce earthquake related risks are limited, and there is a gap between scientific community and society. To establish the missing link between seismology and citizens we have initiated an educational approach called Seismology at School in Nepal and a total of 30 low-cost seismometers have been installed in schools. The program is engaging the public on earthquake related activities and found to be effective in raising the awareness levels of children, promoting broader earthquake learning in the community, thus improving the adaptive capacities and preparedness for future earthquakes. The aim of this work is to present a simple tutorial of earthquake location mainly for Nepali citizens and school teachers. We describe procedures for computing an earthquake epicenter using an open and user-friendly software, Seisgram2K. This tutorial helps the public to have first-order information on earthquakes, by allowing to locate epicenters, which will increase the frequency of earthquake discussion in the community. Open seismic data and the earthquake location tutorial helps to inspire the next generation to study Earth sciences, which is very important and required for earthquake prone countries, like Nepal

Techno-economic assessment guidelines for CO2 utilization

Carbon Capture and Utilization (CCU) is an emerging technology field that can replace fossil carbon value chains, and that has a significant potential to achieve emissions mitigation or even “negative emissions”—however in many cases with challenging technology feasibility and economic viability. Further challenges arise in the decision making for CCU technology research, development, and deployment, in particular when allocating funding or time resources. No generally accepted techno-economic assessment (TEA) standard has evolved, and assessment studies often result in “apples vs. oranges” comparisons, a lack of transparency and a lack of comparability to other studies. A detailed guideline for systematic techno-economic (TEA) and life cycle assessment (LCA) for CCU technologies was developed; this paper shows a summarized version of the TEA guideline, which includes distinct and prioritized (shall and should) rules and which allows conducting TEA in parallel to LCA. The TEA guideline was developed in a co-operative and creative approach with roughly 50 international experts and is based on a systematic literature review as well as on existing best practices from TEA and LCA from the areas of industry, academia, and policy. To the best of our knowledge, this guideline is the first TEA framework with a focus on CCU technologies and the first that is designed to be conducted in parallel to LCA due to aligned vocabulary and assessment steps, systematically including technology maturity. Therefore, this work extends current literature, improving the design, implementation, and reporting approaches of TEA studies for CCU technologies. Overall, the application of this TEA guideline aims at improved comparability of TEA studies, leading to improved decision making and more efficient allocation of funds and time resources for the research, development, and deployment of CCU technologies

Moho depths beneath the European Alps: a homogeneously processed map and receiver functions database

We use seismic waveform data from the AlpArray Seismic Network and three other temporary seismic networks, to perform receiver function (RF) calculations and time-to-depth migration to update the knowledge of the Moho discontinuity beneath the broader European Alps. In particular, we set up a homogeneous processing scheme to compute RFs using the time-domain iterative deconvolution method and apply consistent quality control to yield 112 205 high-quality RFs. We then perform time-to-depth migration in a newly implemented 3D spherical coordinate system using a European-scale reference P and S wave velocity model. This approach, together with the dense data coverage, provide us with a 3D migrated volume, from which we present migrated profiles that reflect the first-order crustal thickness structure. We create a detailed Moho map by manually picking the discontinuity in a set of orthogonal profiles covering the entire area. We make the RF dataset, the software for the entire processing workflow, as well as the Moho map, openly available; these open-access datasets and results will allow other researchers to build on the current study.</p

Data for: Detailed spatiotemporal analysis of the tectonic stress regime near the central Alpine Fault, New Zealand

Focal mechanism earthquake catalog for the manuscript of Michailos et al 2019 (Tectonophysics; submitted)

Data for: Detailed spatiotemporal analysis of the tectonic stress regime near the central Alpine Fault, New Zealand

Focal mechanism earthquake catalog for the manuscript of Michailos et al 2019 (Tectonophysics; submitted).THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Crustal Thermal Structure and Exhumation Rates in the Southern Alps Near the Central Alpine Fault, New Zealand

© 2020. American Geophysical Union. All Rights Reserved. We investigate orogenic uplift rates and the thermal structure of the crust in the hanging wall of the Alpine Fault, New Zealand, using the hypocenters of 7,719 earthquakes that occurred in the central Southern Alps between late 2008 and early 2017, and previously published thermochronological data. We assume that the base of the seismogenic zone corresponds to a brittle-ductile transition at some fixed temperature, which we estimate by fitting the combined thermochronological data and distribution of seismicity using a multi-1-D approach. We find that exhumation rates vary from 1 to 8 mm/yr, with maximum values observed in the area of highest topography near Aoraki/Mount Cook, a finding consistent with previous geologic and geodetic analyses. We estimate the temperature of the brittle-ductile transition beneath the Southern Alps to be 410–430°C, which is higher than expected for Alpine Fault rocks whose bulk lithology is likely dominated by quartz. The high estimated temperatures at the base of the seismogenic zone likely reflect the unmodeled effects of high fluid pressures or strain rates

Detailed spatiotemporal analysis of the tectonic stress regime near the central Alpine Fault, New Zealand

We construct a new data set of 845 focal mechanisms derived from microseismicity recorded between late 2008 and early 2017, to investigate the state of stress near the central Alpine Fault, a major obliquely convergent plate boundary fault. We obtain an average maximum horizontal compressive stress orientation, SHmax, of 121 ± 11°, which is uniform to first-order along the length of the central Southern Alps. We also make use of the local magnitudes of the earthquakes with focal mechanisms to examine the spatial patterns of seismic moment release and obtain a relatively uniform cumulative seismic moment release distribution adjacent to the central Alpine Fault, which appears to be independent of both the perpendicular and parallel distances to the fault. We observe an average angle between SHmax and the Alpine Fault of 66°, which is consistent with previous observations in the northern and southern sections of the Alpine Fault. This result implies that central Alpine Fault is not optimally oriented for reactivation. Detailed temporal investigations using two different approaches did not show any systematic change of the stress parameters with time. We also examine the distribution of the shear to normal stress ratio on the fault and do not observe any significant spatial variation along the Alpine Fault. This lack of variation combined with the high angle between the fault strike and SHmax implies that the fault is unfavourably oriented for slip

An improved kinetic modelling of woody biomass gasification in a downdraft reactor based on the pyrolysis gas evolution

Biomass gasification technology is evolving and more research through modelling alongside the experimental work needs to be performed. In the past, all the attention has been concentrated on the combustion and reduction stages to be the controlling reactions while the pyrolysis is modelled as an instantaneous process. In this study, a new enhanced model for the gasification process in the downdraft reactor is proposed with a more realistic representation of the pyrolysis stage as a temperature-dependent sequential release of gases. The evolution of the pyrolysis gas, followed by the combustion and reduction reactions, are kinetically controlled in the proposed model which is developed within the Aspen Plus software package. The simulation of the reactor temperature profile and the evolution of the pyrolysis gas is carried out in an integrated MATLAB and Aspen Plus model. The proposed model has been validated against experimental data obtained from the gasification of different woody biomass types and considering a range of scale reactor and power loads. The predicted results are in very good agreement with the experimental data, and therefore the model can be used with confidence to perform a sensitivity analysis to predict the performance of a gasifier at different load levels corresponding to the air flow rate range of 3–10 L/s. As the supplied air flow rate increases, the LHV decreases but the gas yield behaves conversely, and in turn the cold gas efficiency is maintained at a good level of energy conversion at ≥ 70%. Furthermore, the variation in the biomass moisture content, which is commonly in the range of 5–25 % has a significant effect on the gasification efficiency. Such that biomass that has a high moisture content substantially reduces the CO content and consequently the LHV of the produced gas. Hence, it is important to maintain the moisture content at the lowest level

Variations in Seismogenic Thickness Along the Central Alpine Fault, New Zealand, Revealed by a Decade's Relocated Microseismicity

©2018. American Geophysical Union. All Rights Reserved. The Alpine Fault is an oblique strike-slip fault that is known to fail in large magnitude (M7–8) earthquakes, yet it is currently seismically quiescent. We examine the low-magnitude earthquake activity occurring along the central portion of the Alpine Fault using seismic data from five temporary seismic networks deployed for various lengths of time between late 2008 and early 2017. Starting from continuous seismic data, we detect earthquake arrivals and construct the longest and most extensive microearthquake catalog for the central Alpine Fault region to date, containing 9,111 earthquakes. This enables us to study the distribution and characteristics of the seismicity in unprecedented detail. Earthquake locations are constrained by high-quality automatic and manual picks, and we perform relocations using waveform cross-correlation to better constrain hypocenters. We have derived a new local magnitude scale calibrated by M w values. Magnitudes range between M L −1.2 and 4.6, and our catalog is complete above M L 1.1. Earthquakes mainly occur southeast of the Alpine Fault (in the hanging wall) and exhibit low magnitudes. We observe a lack of seismicity beneath Aoraki/Mount Cook, which we associate with high uplift rates and high heat flow. Seismogenic cutoff depths vary along the strike of the Alpine Fault from 8 km, beneath the highest topography, to 20 km in the adjacent areas