# David Dempsey: research papers

> Open, machine-readable copies of 63 peer-reviewed papers by David Dempsey (University of Canterbury, ORCID 0000-0003-2135-5129) on geothermal and magmatic systems, induced seismicity, volcanic eruption forecasting, CO2 and hydrogen storage, groundwater and related topics. 60 have an open PDF here.

Every paper has:
- an HTML summary page: https://ddempsey.github.io/papers/<slug>/
- the same page as Markdown: https://ddempsey.github.io/papers/<slug>/index.md
- BibTeX: https://ddempsey.github.io/papers/<slug>/citation.bib
- where the publisher permits, an open PDF, and where available, the full text as Markdown (fulltext.md)

Machine-readable catalogue (JSON, all papers, all links): https://ddempsey.github.io/papers.json
All summaries in one file: https://ddempsey.github.io/llms-full.txt
Sitemap: https://ddempsey.github.io/sitemap.xml

When citing, use the DOI (version of record). Hosted copies are labelled as either the published version or the author's accepted manuscript.

## Papers

- [Surrogate-Based probabilistic assessment of hydrogen leakage through abandoned wells in depleted gas reservoirs for underground hydrogen storage](https://ddempsey.github.io/papers/2027-chang-surrogate-probabilistic-assessment-hydrogen-leakage/index.md): Chang Q, Dempsey D, Xu G et al. (2027), *Fuel*. DOI 10.1016/j.fuel.2026.140374. PDF: https://ddempsey.github.io/papers/2027-chang-surrogate-probabilistic-assessment-hydrogen-leakage/chang2027-surrogate-probabilistic-assessment.pdf Full text: https://ddempsey.github.io/papers/2027-chang-surrogate-probabilistic-assessment-hydrogen-leakage/fulltext.md We built a fast statistical approximation of reservoir simulations that predicts whether hydrogen stored in a depleted gas reservoir could leak up an abandoned well. In our models, the distance to that well and the injection rate had the largest effect on leakage probability.
- [A Physics‐Based, Lumped‐Parameter Model for Attributing Natural and Anthropogenic CO2 Emissions From Producing Geothermal Systems](https://ddempsey.github.io/papers/2026-dempsey-physics-lumped-parameter-model-attributing/index.md): Dempsey D (2026), *Water Resources Research*. DOI 10.1029/2026wr044239. PDF: https://ddempsey.github.io/papers/2026-dempsey-physics-lumped-parameter-model-attributing/dempsey2026-physics-lumped-parameter.pdf Full text: https://ddempsey.github.io/papers/2026-dempsey-physics-lumped-parameter-model-attributing/fulltext.md We built a lumped-parameter physics model of CO2 in a producing geothermal reservoir and calibrated it to two New Zealand fields. At Rotokawa, we estimate that metering the power plant overcounts the human-caused change in emissions by 17–45 kt a year, because production reduces natural CO2 discharge at the surface.
- [Socio-economic value of data-driven eruption forecasts to balance false alarms against catastrophic loss](https://ddempsey.github.io/papers/2026-ardid-socio-economic-value-data-driven/index.md): Ardid A, Dempsey D, McDonald G et al. (2026), *Nature Communications*. DOI 10.1038/s41467-026-77242-4. PDF: https://ddempsey.github.io/papers/2026-ardid-socio-economic-value-data-driven/ardid2026-socio-economic-value.pdf Full text: https://ddempsey.github.io/papers/2026-ardid-socio-economic-value-data-driven/fulltext.md We compared the cost of false alarms with the loss from missed eruptions for eruption forecasts at five volcanoes. In retrospective tests, with documented losses at two volcanoes and assumed losses at three, acting on the forecasts could have reduced losses by 30 to 90%, despite many false alarms.
- [A Machine‐Learning Classification for Torlesse Composite Terrane Petrofacies and its Application to Sediment Provenance](https://ddempsey.github.io/papers/2026-parker-machine-learning-classification-torlesse-composite/index.md): Parker MO, Dempsey DE, Sagar MW et al. (2026), *New Zealand Journal of Geology and Geophysics*. DOI 10.1002/jgo2.70064. PDF: https://ddempsey.github.io/papers/2026-parker-machine-learning-classification-torlesse-composite/parker2026-machine-learning-classification.pdf Full text: https://ddempsey.github.io/papers/2026-parker-machine-learning-classification-torlesse-composite/fulltext.md We trained four machine-learning algorithms to assign sandstone clasts to source regions of the Torlesse Composite Terrane, including the newly recognised Kaweka Terrane. Combined by equal vote, they reached a balanced accuracy of 80% on unseen samples, counting a two-two split as correct if either group was right.
- [From forecast skill to economic value: sub-hourly wildfire potential forecasting across Australian regions](https://ddempsey.github.io/papers/2026-ardid-forecast-skill-economic-value-sub/index.md): Ardid A, Power A, Valencia A et al. (2026), *International Journal of Wildland Fire*. DOI 10.1071/wf25221. PDF: https://ddempsey.github.io/papers/2026-ardid-forecast-skill-economic-value-sub/ardid2026-forecast-skill-economic.pdf Full text: https://ddempsey.github.io/papers/2026-ardid-forecast-skill-economic-value-sub/fulltext.md We tested a machine learning forecast of fire potential, updated every 30 minutes, in three Australian regions. On the Sunshine Coast it detected twice as many pre-fire periods as the Fire Behaviour Index, at a similar false alarm rate. Projected savings were nearly three times higher. Both are upper bounds.
- [Impacts of reservoir permeability anisotropy on hydrogen migration and recovery efficiency in geological storage](https://ddempsey.github.io/papers/2026-liu-impacts-reservoir-permeability-anisotropy-hydrogen/index.md): Liu J, Dempsey D, Nicol A et al. (2026), *Fuel*. DOI 10.1016/j.fuel.2025.137596. PDF: https://ddempsey.github.io/papers/2026-liu-impacts-reservoir-permeability-anisotropy-hydrogen/liu2026-impacts-reservoir-permeability.pdf Full text: https://ddempsey.github.io/papers/2026-liu-impacts-reservoir-permeability-anisotropy-hydrogen/fulltext.md We simulated hydrogen storage in a depleted gas reservoir to test how direction-dependent permeability affects how much stored hydrogen can be withdrawn again. In our models, lower vertical permeability raised recovery for most well layouts, and the orientation of horizontal wells changed it by up to 8 percentage points.
- [Effects of reservoir interlayers on hydrogen migration and distribution in underground hydrogen storage](https://ddempsey.github.io/papers/2026-liu-effects-reservoir-interlayers-hydrogen-migration/index.md): Liu J, Dempsey D, Nicol A et al. (2026), *International Journal of Hydrogen Energy*. DOI 10.1016/j.ijhydene.2026.153704. PDF: https://ddempsey.github.io/papers/2026-liu-effects-reservoir-interlayers-hydrogen-migration/liu2026-effects-reservoir-interlayers.pdf Full text: https://ddempsey.github.io/papers/2026-liu-effects-reservoir-interlayers-hydrogen-migration/fulltext.md In our models of hydrogen storage in a layered gas reservoir with the well open to every layer, thin low-permeability layers (interlayers) slowed the rise of hydrogen and raised the share recovered. At low permeability, a model with diffusion predicted more hydrogen in these layers than one without.
- [Determination of interfacial tension for H2-H2S-water and CH4-H2S-water mixtures under different geological conditions for underground hydrogen storage](https://ddempsey.github.io/papers/2026-chang-determination-interfacial-tension-h2s-water/index.md): Chang Q, Dempsey D, Huang L (2026), *Journal of Energy Storage*. DOI 10.1016/j.est.2025.119683. PDF: https://ddempsey.github.io/papers/2026-chang-determination-interfacial-tension-h2s-water/chang2026-determination-interfacial-tension.pdf Full text: https://ddempsey.github.io/papers/2026-chang-determination-interfacial-tension-h2s-water/fulltext.md Hydrogen stored in depleted oil and gas reservoirs may mix with hydrogen sulfide (H2S). In our molecular simulations, H2S lowered the interfacial tension between the gas and pore water more than pressure or temperature did. We fitted a linear formula in H2S content, pressure and temperature to predict it.
- [Preferential seawater intrusion in a heterogeneous alluvial aquifer that extends offshore: Insights from numerical modeling](https://ddempsey.github.io/papers/2025-cleary-preferential-seawater-intrusion-heterogeneous-alluvial/index.md): Cleary CA, Sarris TS, Morgan LK et al. (2025), *Journal of Hydrology*. DOI 10.1016/j.jhydrol.2025.133455. PDF: https://ddempsey.github.io/papers/2025-cleary-preferential-seawater-intrusion-heterogeneous-alluvial/cleary2025-preferential-seawater-intrusion.pdf Full text: https://ddempsey.github.io/papers/2025-cleary-preferential-seawater-intrusion-heterogeneous-alluvial/fulltext.md We modelled seawater moving inland through a gravel aquifer beneath the Canterbury coast. In our model, seawater moved preferentially through high-conductivity gravel. In places, the salt/fresh water interface moved more than five times faster than a uniform model with dispersion predicts.
- [Advanced Hydrogeochemical Coupling in Carbon Sequestration: A 4D Spatiotemporal Fourier Neural Operator–Driven Modeling Framework](https://ddempsey.github.io/papers/2025-rui-advanced-hydrogeochemical-coupling-carbon-sequestration/index.md): Rui Z, Zhou K, Hu T et al. (2025), *SPE Journal*. DOI 10.2118/228397-pa.
- [The Research and Impact of the Works by Don Nield](https://ddempsey.github.io/papers/2025-becker-research-impact-works-don-nield/index.md): Becker S, Dempsey D, Zhao D (2025), *Transport in Porous Media*. DOI 10.1007/s11242-025-02199-9. PDF: https://ddempsey.github.io/papers/2025-becker-research-impact-works-don-nield/becker2025-research-impact-works.pdf Full text: https://ddempsey.github.io/papers/2025-becker-research-impact-works-don-nield/fulltext.md We review the published work of Don Nield, a University of Auckland mathematician who studied convection and flow in porous media for more than 50 years. Scopus indexes 249 of his works, with 22,480 citations in total.
- [Quantifying Interannual Variations in Groundwater Fluxes Within a Braidplain Aquifer Using Active‐Distributed Temperature Sensing](https://ddempsey.github.io/papers/2025-sai-louie-quantifying-interannual-variations-groundwater-fluxes/index.md): Sai Louie AJ, Morgan LK, Dempsey D et al. (2025), *Water Resources Research*. DOI 10.1029/2024wr039328. PDF: https://ddempsey.github.io/papers/2025-sai-louie-quantifying-interannual-variations-groundwater-fluxes/sai-louie2025-louie-quantifying-interannual.pdf Full text: https://ddempsey.github.io/papers/2025-sai-louie-quantifying-interannual-variations-groundwater-fluxes/fulltext.md Over nearly three years we used heated fibre optic cables to measure groundwater flow beneath a braided river in Canterbury, New Zealand. River flow varied about tenfold between surveys, but average groundwater flux remained between 2.4 and 5.9 m/day. Riverbed changes after a flood likely had the largest effect.
- [Impact of operational parameters on water invasion in underground hydrogen storage: A numerical investigation of the Ahuroa field, New Zealand](https://ddempsey.github.io/papers/2025-liu-impact-operational-parameters-water-invasion/index.md): Liu J, Dempsey D, Nicol A et al. (2025), *International Journal of Hydrogen Energy*. DOI 10.1016/j.ijhydene.2025.150236. PDF: https://ddempsey.github.io/papers/2025-liu-impact-operational-parameters-water-invasion/liu2025-impact-operational-parameters.pdf Full text: https://ddempsey.github.io/papers/2025-liu-impact-operational-parameters-water-invasion/fulltext.md We modelled hydrogen storage in the depleted Ahuroa gas field, New Zealand, to evaluate how operating choices affect water rising toward the wells. In our model, longer or faster withdrawal and a smaller cushion of gas produced the most water.
- [Forecasting Eruptions at Steamboat Geyser: Time Scales, Differentiability, and Detectability of Seismic Precursors Through Data‐Driven Methods](https://ddempsey.github.io/papers/2025-ardid-forecasting-eruptions-steamboat-geyser-time/index.md): Ardid A, Barth A, Dempsey D et al. (2025), *Journal of Geophysical Research: Machine Learning and Computation*. DOI 10.1029/2024jh000569. PDF: https://ddempsey.github.io/papers/2025-ardid-forecasting-eruptions-steamboat-geyser-time/ardid2025-forecasting-eruptions-steamboat.pdf Full text: https://ddempsey.github.io/papers/2025-ardid-forecasting-eruptions-steamboat-geyser-time/fulltext.md A machine learning model trained on signals in the 2018 seismic record of Steamboat Geyser showed a fair ability to separate pre-eruption periods from other times in later data. Its eruption probability peaked at 12.6% within 18 hours of an eruption, compared with 8.1% from eruption intervals alone.
- [Ergodic seismic precursors and transfer learning for short term eruption forecasting at data scarce volcanoes](https://ddempsey.github.io/papers/2025-ardid-ergodic-seismic-precursors-transfer-learning/index.md): Ardid A, Dempsey D, Caudron C et al. (2025), *Nature Communications*. DOI 10.1038/s41467-025-56689-x. PDF: https://ddempsey.github.io/papers/2025-ardid-ergodic-seismic-precursors-transfer-learning/ardid2025-ergodic-seismic-precursors.pdf Full text: https://ddempsey.github.io/papers/2025-ardid-ergodic-seismic-precursors-transfer-learning/fulltext.md We trained forecasting models on seismic data from 41 eruptions at 24 volcanoes and tested each on a volcano left out of training. They scored better than a seismic amplitude benchmark and, at three volcanoes, close to models trained on that volcano alone. This suggests precursors are shared between volcanoes.
- [Sub-hourly forecasting of fire potential using machine learning on time series of surface weather variables](https://ddempsey.github.io/papers/2025-ardid-sub-hourly-forecasting-fire-potential/index.md): Ardid A, Valencia A, Power A et al. (2025), *International Journal of Wildland Fire*. DOI 10.1071/wf24113. PDF: https://ddempsey.github.io/papers/2025-ardid-sub-hourly-forecasting-fire-potential/ardid2025-sub-hourly-forecasting.pdf Full text: https://ddempsey.github.io/papers/2025-ardid-sub-hourly-forecasting-fire-potential/fulltext.md We trained machine learning models on 15 years of half-hourly records from one weather station on the Sunshine Coast, Australia, to recognise the weather in the days before fires. Tested on fires withheld from training, 11 of the 15 fires occurred during a warning from our 10-day model.
- [Techno-economic analysis of geothermal combined with direct and biomass-based carbon dioxide removal for high-temperature hydrothermal systems](https://ddempsey.github.io/papers/2025-titus-techno-economic-analysis-geothermal-combined/index.md): Titus KA, Dempsey D, Peer RAM et al. (2025), *Geothermics*. DOI 10.1016/j.geothermics.2024.103159. PDF: https://ddempsey.github.io/papers/2025-titus-techno-economic-analysis-geothermal-combined/titus2025-techno-economic-analysis.pdf Full text: https://ddempsey.github.io/papers/2025-titus-techno-economic-analysis-geothermal-combined/fulltext.md We modelled geothermal power plants that also remove CO2 from the atmosphere, by burning forestry residues or by capturing CO2 from air, and store it dissolved in reinjected water. At USD 100 per tonne of CO2, the biomass design had the lowest median costs of electricity and of carbon abatement.
- [Influence of hydrogen sulfide on gas-water interface in underground hydrogen storage: A molecular dynamics study](https://ddempsey.github.io/papers/2024-chang-influence-hydrogen-sulfide-gas-water/index.md): Chang Q, Huang L, McKenzie K et al. (2024), *Journal of Energy Storage*. DOI 10.1016/j.est.2024.112766. PDF: https://ddempsey.github.io/papers/2024-chang-influence-hydrogen-sulfide-gas-water/chang2024-influence-hydrogen-sulfide.pdf Full text: https://ddempsey.github.io/papers/2024-chang-influence-hydrogen-sulfide-gas-water/fulltext.md We used molecular dynamics simulations to test how hydrogen sulfide, a gas that microbes can produce in underground hydrogen stores, changes the tension between stored gas and pore water. At 343 K and 14.5 MPa, 5% hydrogen sulfide in the gas lowered it by 12% when mixed with hydrogen and by 6% when mixed with methane.
- [Earthquakes Trigger Rapid Flash Boiling Front at Optimal Geologic Conditions](https://ddempsey.github.io/papers/2024-sanchez-alfaro-earthquakes-trigger-rapid-flash-boiling/index.md): Sanchez‐Alfaro P, Wallis I, Iturrieta P et al. (2024), *Geophysical Research Letters*. DOI 10.1029/2023gl108109. PDF: https://ddempsey.github.io/papers/2024-sanchez-alfaro-earthquakes-trigger-rapid-flash-boiling/sanchez‐alfaro2024-alfaro-earthquakes-trigger.pdf Full text: https://ddempsey.github.io/papers/2024-sanchez-alfaro-earthquakes-trigger-rapid-flash-boiling/fulltext.md An earthquake can make hot water boil in the fracture between two faults. In our models this flashing was limited, and complete flashing is highly unlikely. Opening was largest where the faults were separated by about 10% of their length and overlapped by about 2.5%.
- [From carbon neutral to carbon negative: a theoretical bioenergy and CO2 removal retrofit at Ngāwhā geothermal power station](https://ddempsey.github.io/papers/2024-titus-carbon-neutral-carbon-negative-theoretical/index.md): Titus K, Dempsey D, Peer R et al. (2024), *Journal of the Royal Society of New Zealand*. DOI 10.1080/03036758.2024.2385807. PDF: https://ddempsey.github.io/papers/2024-titus-carbon-neutral-carbon-negative-theoretical/titus2024-carbon-neutral-carbon.pdf Full text: https://ddempsey.github.io/papers/2024-titus-carbon-neutral-carbon-negative-theoretical/fulltext.md We modelled a biomass boiler retrofit that adds 1 MWe to Station-1 at the Ngāwhā geothermal power station. Dissolving the biomass CO2 in reinjected fluid could remove up to 15,900 tonnes of CO2 a year. The design that also sells its surplus CO2 had the lowest costs in our model.
- [Multitimescale Template Matching: Discovering Eruption Precursors across Diverse Volcanic Settings](https://ddempsey.github.io/papers/2024-ardid-multitimescale-template-matching-discovering-eruption/index.md): Ardid A, Dempsey D, Corry J et al. (2024), *Seismological Research Letters*. DOI 10.1785/0220240012. PDF: https://ddempsey.github.io/papers/2024-ardid-multitimescale-template-matching-discovering-eruption/ardid2024-multitimescale-template-matching.pdf Full text: https://ddempsey.github.io/papers/2024-ardid-multitimescale-template-matching-discovering-eruption/fulltext.md
- [Prospectivity analysis for underground hydrogen storage, Taranaki basin, Aotearoa New Zealand: A multi-criteria decision-making approach](https://ddempsey.github.io/papers/2024-higgs-prospectivity-analysis-underground-hydrogen-storage/index.md): Higgs KE, Strogen DP, Nicol A et al. (2024), *International Journal of Hydrogen Energy*. DOI 10.1016/j.ijhydene.2024.05.098. PDF: https://ddempsey.github.io/papers/2024-higgs-prospectivity-analysis-underground-hydrogen-storage/higgs2024-prospectivity-analysis-underground.pdf Full text: https://ddempsey.github.io/papers/2024-higgs-prospectivity-analysis-underground-hydrogen-storage/fulltext.md We ranked 40 possible sites for storing hydrogen underground in Taranaki Basin, New Zealand. Depleted Paleogene gas and gas-cap reservoirs ranked highest. Our results suggest that one or two of the best sites could hold more than the country's projected 2050 storage need.
- [Eruption Forecasting Model for Copahue Volcano (Southern Andes) Using Seismic Data and Machine Learning: A Joint Interpretation with Geodetic Data (GNSS and InSAR)](https://ddempsey.github.io/papers/2024-cabrera-eruption-forecasting-model-copahue-volcano/index.md): Cabrera L, Ardid A, Melchor I et al. (2024), *Seismological Research Letters*. DOI 10.1785/0220240022. PDF: https://ddempsey.github.io/papers/2024-cabrera-eruption-forecasting-model-copahue-volcano/cabrera2024-eruption-forecasting-model.pdf Full text: https://ddempsey.github.io/papers/2024-cabrera-eruption-forecasting-model-copahue-volcano/fulltext.md
- [Testing the reproducibility of active-distributed temperature sensing for measuring groundwater specific discharge beneath a braided river](https://ddempsey.github.io/papers/2024-sai-louie-testing-reproducibility-active-distributed-temperature/index.md): Sai Louie AJ, Morgan LK, Banks EW et al. (2024), *Journal of Hydrology*. DOI 10.1016/j.jhydrol.2024.130877. PDF: https://ddempsey.github.io/papers/2024-sai-louie-testing-reproducibility-active-distributed-temperature/sai-louie2024-louie-testing-reproducibility.pdf Full text: https://ddempsey.github.io/papers/2024-sai-louie-testing-reproducibility-active-distributed-temperature/fulltext.md We heated a 100 m fibre optic cable beneath New Zealand's Waikirikiri-Selwyn River twelve times in 24 hours. The median groundwater flow of each survey lay between 3.5 and 4.0 m per day, within the measurement error of the method. Repeat surveys could therefore measure seasonal changes in river loss.
- [Molecular dynamics insights into gas-water interfacial tension: Optimizing hydrogen storage in subsurface conditions](https://ddempsey.github.io/papers/2024-chang-molecular-dynamics-insights-gas-water/index.md): Chang Q, Dempsey D, Zhang L et al. (2024), *International Journal of Hydrogen Energy*. DOI 10.1016/j.ijhydene.2024.03.341. PDF: https://ddempsey.github.io/papers/2024-chang-molecular-dynamics-insights-gas-water/chang2024-molecular-dynamics-insights.pdf Full text: https://ddempsey.github.io/papers/2024-chang-molecular-dynamics-insights-gas-water/fulltext.md In molecular simulations at underground hydrogen storage conditions, mixing a cushion gas into hydrogen lowered the tension at the boundary between gas and pore water. Carbon dioxide lowered it substantially up to a 40% share, and at a lower rate above that. Methane lowered it at a steady rate.
- [Active-distributed temperature sensing dataset beneath a braided river](https://ddempsey.github.io/papers/2023-sai-louie-active-distributed-temperature-sensing-dataset/index.md): Sai Louie AJ, Morgan LK, Banks EW et al. (2023), *Data in Brief*. DOI 10.1016/j.dib.2023.109756.
- [Shallow groundwater characterisation and hydrograph classification in the coastal city of Ōtautahi/Christchurch, New Zealand](https://ddempsey.github.io/papers/2023-bosserelle-shallow-groundwater-characterisation-hydrograph-classification/index.md): Bosserelle AL, Morgan LK, Dempsey DE et al. (2023), *Hydrogeology Journal*. DOI 10.1007/s10040-023-02745-z. PDF: https://ddempsey.github.io/papers/2023-bosserelle-shallow-groundwater-characterisation-hydrograph-classification/bosserelle2023-shallow-groundwater-characterisation.pdf Full text: https://ddempsey.github.io/papers/2023-bosserelle-shallow-groundwater-characterisation-hydrograph-classification/fulltext.md Records from 265 monitoring wells in Christchurch, New Zealand, show that from 2016 to 2020 the median depth to the water table was 1 m or less below about 62% of the mapped city. In a preliminary one-week comparison, wells nearer tidal rivers followed the ocean tide more closely.
- [Using Template Matching to Detect Hidden Fluid Release Episodes Beneath Crater Lakes in Ruapehu, Copahue, and Kawah Ijen Volcanoes](https://ddempsey.github.io/papers/2023-ardid-template-matching-detect-hidden-fluid/index.md): Ardid A, Dempsey D, Caudron C et al. (2023), *Journal of Geophysical Research: Solid Earth*. DOI 10.1029/2023jb026729. PDF: https://ddempsey.github.io/papers/2023-ardid-template-matching-detect-hidden-fluid/ardid2023-template-matching-detect.pdf Full text: https://ddempsey.github.io/papers/2023-ardid-template-matching-detect-hidden-fluid/fulltext.md We searched Ruapehu seismic data from 2006 to 2021 for a tremor pattern seen before the 2019 Whakaari eruption. We then looked for a tremor peak and exponential decay after each match. Six events passed, including a 2009 event that we classify as a fluid release into the crater lake.
- [Association Between Injection and Microseismicity in Geothermal Fields With Multiple Wells: Data‐Driven Modeling of Rotokawa, New Zealand, and Húsmúli, Iceland](https://ddempsey.github.io/papers/2023-yu-association-injection-microseismicity-geothermal-fields/index.md): Yu P, Dempsey D, Rinaldi AP et al. (2023), *Journal of Geophysical Research: Solid Earth*. DOI 10.1029/2022jb025952. PDF: https://ddempsey.github.io/papers/2023-yu-association-injection-microseismicity-geothermal-fields/yu2023-association-injection-microseismicity.pdf Full text: https://ddempsey.github.io/papers/2023-yu-association-injection-microseismicity-geothermal-fields/fulltext.md We used data-driven methods to find which injection wells are associated with small earthquakes at the Rotokawa (New Zealand) and Húsmúli (Iceland) fields. Injection was more closely associated with earthquake rates averaged over weeks than over days. At Rotokawa, we found no evidence that rapid injection changes trigger earthquakes.
- [Identification of Seismo‐Volcanic Regimes at Whakaari/White Island (New Zealand) Via Systematic Tuning of an Unsupervised Classifier](https://ddempsey.github.io/papers/2023-steinke-identification-seismo-volcanic-regimes-whakaari/index.md): Steinke B, Jolly AD, Carniel R et al. (2023), *Journal of Geophysical Research: Solid Earth*. DOI 10.1029/2022jb026221. PDF: https://ddempsey.github.io/papers/2023-steinke-identification-seismo-volcanic-regimes-whakaari/steinke2023-identification-seismo-volcanic.pdf Full text: https://ddempsey.github.io/papers/2023-steinke-identification-seismo-volcanic-regimes-whakaari/fulltext.md We tuned an unsupervised classifier on 12.5 years of volcanic tremor at Whakaari. It separated background from unrest. In a retrospective analysis, its output changed to unrest regimes 6 weeks before the August 2012 eruption and about 3.5 months before the December 2019 eruption.
- [Physics-Based Forecasting of Induced Seismicity at Groningen Gas Field, The Netherlands: Post Hoc Evaluation and Forecast Update](https://ddempsey.github.io/papers/2023-dempsey-physics-forecasting-induced-seismicity-groningen/index.md): Dempsey DE, Suckale J (2023), *Seismological Research Letters*. DOI 10.1785/0220220317. PDF: https://ddempsey.github.io/papers/2023-dempsey-physics-forecasting-induced-seismicity-groningen/dempsey2023-physics-forecasting-induced.pdf Full text: https://ddempsey.github.io/papers/2023-dempsey-physics-forecasting-induced-seismicity-groningen/fulltext.md We tested our 2017 earthquake forecast for the Groningen gas field against the earthquakes that followed, then updated it. For 2021 to 2030, the largest event has a 1% chance of exceeding magnitude 3.8 if ruptures are confined to the reservoir, and 5.4 if they can extend below it.
- [Carbon negative geothermal: Theoretical efficiency and sequestration potential of geothermal-BECCS energy cycles](https://ddempsey.github.io/papers/2023-titus-carbon-negative-geothermal-theoretical-efficiency/index.md): Titus KA, Dempsey DE, Peer RAM (2023), *International Journal of Greenhouse Gas Control*. DOI 10.1016/j.ijggc.2022.103813. PDF: https://ddempsey.github.io/papers/2023-titus-carbon-negative-geothermal-theoretical-efficiency/titus2023-carbon-negative-geothermal.pdf Full text: https://ddempsey.github.io/papers/2023-titus-carbon-negative-geothermal-theoretical-efficiency/fulltext.md We modelled four power plant designs that burn forestry waste alongside a 160 °C geothermal resource and dissolve the flue CO2 in reinjected water. Per kg/s of geofluid drawn, they generated 62–589 kWe, the top figure mostly from biomass, and could store 217–675 tonnes of CO2 a year.
- [Active distributed temperature sensing to assess surface water–groundwater interaction and river loss in braided river systems](https://ddempsey.github.io/papers/2022-banks-active-distributed-temperature-sensing-assess/index.md): Banks EW, Morgan LK, Sai Louie AJ et al. (2022), *Journal of Hydrology*. DOI 10.1016/j.jhydrol.2022.128667. PDF: https://ddempsey.github.io/papers/2022-banks-active-distributed-temperature-sensing-assess/banks2022-active-distributed-temperature.pdf Full text: https://ddempsey.github.io/papers/2022-banks-active-distributed-temperature-sensing-assess/fulltext.md We installed heated fibre optic cables 5 m beneath the Waikirikiri Selwyn River, a braided river in Canterbury, to measure water leaking from the river into the gravels below. We estimate that groundwater beneath the channel moved at an average of 12.0 and 15.8 m per day in two surveys.
- [Evaluation of short-term probabilistic eruption forecasting at Whakaari, New Zealand](https://ddempsey.github.io/papers/2022-dempsey-evaluation-short-term-probabilistic-eruption/index.md): Dempsey DE, Kempa-Liehr AW, Ardid A et al. (2022), *Bulletin of Volcanology*. DOI 10.1007/s00445-022-01600-5. PDF: https://ddempsey.github.io/papers/2022-dempsey-evaluation-short-term-probabilistic-eruption/dempsey2022-evaluation-short-term.pdf Full text: https://ddempsey.github.io/papers/2022-dempsey-evaluation-short-term-probabilistic-eruption/fulltext.md We ran an eruption forecaster at Whakaari for 18 months and filtered out the earthquakes that caused its three false positives. In a test with the 2019 eruption withheld from training, a calibrated version gave a 2 to 4% chance in 48 hours, up to 400 times its lowest level.
- [Seismic precursors to the Whakaari 2019 phreatic eruption are transferable to other eruptions and volcanoes](https://ddempsey.github.io/papers/2022-ardid-seismic-precursors-whakaari-2019-phreatic/index.md): Ardid A, Dempsey D, Caudron C et al. (2022), *Nature Communications*. DOI 10.1038/s41467-022-29681-y. PDF: https://ddempsey.github.io/papers/2022-ardid-seismic-precursors-whakaari-2019-phreatic/ardid2022-seismic-precursors-whakaari.pdf Full text: https://ddempsey.github.io/papers/2022-ardid-seismic-precursors-whakaari-2019-phreatic/fulltext.md We searched seismic tremor recorded before 18 eruptions at six volcanoes for a shared precursor. A rise in the ratio of medium- to high-frequency tremor recurred before steam-driven eruptions at Whakaari and, less clearly, Ruapehu and Tongariro. At Whakaari in 2019, we interpret it as shallow sealing and pressurisation.
- [Techno-Economic feasibility of enhanced geothermal systems (EGS) with partially bridging Multi-Stage fractures for district heating applications](https://ddempsey.github.io/papers/2022-yu-techno-economic-feasibility-enhanced-geothermal/index.md): Yu P, Dempsey D, Archer R (2022), *Energy Conversion and Management*. DOI 10.1016/j.enconman.2022.115405. PDF: https://ddempsey.github.io/papers/2022-yu-techno-economic-feasibility-enhanced-geothermal/yu2022-techno-economic-feasibility.pdf Full text: https://ddempsey.github.io/papers/2022-yu-techno-economic-feasibility-enhanced-geothermal/fulltext.md We modelled a geothermal heating scheme that forces water through fractured hot rock between two horizontal wells. In a modelled case study at Qiabuqia, China, a 14-fracture design gave a median profit of USD 110 million over 20 years, with a 95% range of USD 24 to 185 million.
- [Hydrothermal Cooling as a Requirement for Short Storage of Silicic Magmas](https://ddempsey.github.io/papers/2021-kelly-hydrothermal-cooling-requirement-short-storage/index.md): Kelly LJ, Gualda GAR, Gravley DM et al. (2021), *Geochemistry, Geophysics, Geosystems*. DOI 10.1029/2021gc009794. PDF: https://ddempsey.github.io/papers/2021-kelly-hydrothermal-cooling-requirement-short-storage/kelly2021-hydrothermal-cooling-requirement.pdf Full text: https://ddempsey.github.io/papers/2021-kelly-hydrothermal-cooling-requirement-short-storage/fulltext.md Magma for large eruptions in New Zealand's Taupō Volcanic Zone appears to have crystallised within decades to centuries. In our calculations, conduction through rock took over 1,000 years to remove the heat. Circulating groundwater above the magma, with a heat output of about 1,000 MW, could remove it within decades.
- [A three-dimensional coupled thermo-hydro-mechanical numerical model with partially bridging multi-stage contact fractures in horizontal-well enhanced geothermal system](https://ddempsey.github.io/papers/2021-yu-three-dimensional-coupled-thermo-hydro/index.md): Yu P, Dempsey D, Archer R (2021), *International Journal of Rock Mechanics and Mining Sciences*. DOI 10.1016/j.ijrmms.2021.104787. PDF: https://ddempsey.github.io/papers/2021-yu-three-dimensional-coupled-thermo-hydro/yu2021-three-dimensional-coupled.pdf Full text: https://ddempsey.github.io/papers/2021-yu-three-dimensional-coupled-thermo-hydro/fulltext.md We propose a geothermal well design in which fractures grow alternately from the injection and production wells and stop short of the other well. In our model, this forces water through the rock between fractures and keeps produced water hotter, for the same mass produced, than fractures joining both wells.
- [Heat Transfer Through the Wairakei‐Tauhara Geothermal System Quantified by Multi‐Channel Data Modeling](https://ddempsey.github.io/papers/2021-ardid-heat-transfer-wairakei-tauhara-geothermal/index.md): Ardid A, Archer R, Bertrand E et al. (2021), *Geophysical Research Letters*. DOI 10.1029/2020gl092056. PDF: https://ddempsey.github.io/papers/2021-ardid-heat-transfer-wairakei-tauhara-geothermal/ardid2021-heat-transfer-wairakei.pdf Full text: https://ddempsey.github.io/papers/2021-ardid-heat-transfer-wairakei-tauhara-geothermal/fulltext.md We combined electrical surveys, clay tests on drill cuttings, and well temperature logs to map the clay layer above the Wairakei-Tauhara geothermal reservoir. We estimate that 380 ± 21 MW of heat passes up through this layer. We treat this as a lower bound on the field's total heat output.
- [Bayesian magnetotelluric inversion using methylene blue structural priors for imaging shallow conductors in geothermal fields](https://ddempsey.github.io/papers/2021-ardid-bayesian-magnetotelluric-inversion-methylene-blue/index.md): Ardid A, Dempsey D, Bertrand E et al. (2021), *Geophysics*. DOI 10.1190/geo2020-0226.1. PDF: https://ddempsey.github.io/papers/2021-ardid-bayesian-magnetotelluric-inversion-methylene-blue/ardid2021-bayesian-magnetotelluric-inversion.pdf We developed a way to map the clay layer above a geothermal reservoir from electrical surveys, using clay tests on drill cuttings to reduce the range of possible depths. At Wairākei it returned depth ranges for the layer's boundaries and reduced the uncertainty in the depth of its base.
- [Two-dimensional numerical modelling of strategies to avoid thermal stress induced flow channeling in fractured geothermal reservoirs](https://ddempsey.github.io/papers/2021-rongved-two-dimensional-numerical-modelling-strategies/index.md): Rongved M, Bauer A, Dempsey D et al. (2021), *Geothermics*. DOI 10.1016/j.geothermics.2020.101978. PDF: https://ddempsey.github.io/papers/2021-rongved-two-dimensional-numerical-modelling-strategies/rongved2021-two-dimensional-numerical.pdf Full text: https://ddempsey.github.io/papers/2021-rongved-two-dimensional-numerical-modelling-strategies/fulltext.md Cooling by injected water can concentrate flow into one fracture. In our two-dimensional model of two parallel fractures, flow stayed even or evened out with wider, more alike fractures or a higher injection rate. A high starting rate, or injecting through each fracture in turn, made even flow more likely.
- [Ground motion simulation of hypothetical earthquakes in the upper North Island of New Zealand](https://ddempsey.github.io/papers/2020-dempsey-ground-motion-simulation-hypothetical-earthquakes/index.md): Dempsey D, Eccles JD, Huang J et al. (2020), *New Zealand Journal of Geology and Geophysics*. DOI 10.1080/00288306.2020.1842469. PDF: https://ddempsey.github.io/papers/2020-dempsey-ground-motion-simulation-hypothetical-earthquakes/dempsey2020-ground-motion-simulation.pdf Full text: https://ddempsey.github.io/papers/2020-dempsey-ground-motion-simulation-hypothetical-earthquakes/fulltext.md We simulated the largest credible earthquakes on two faults near Auckland, Hamilton and Tauranga. Sediment basins beneath the Hauraki Rift and Hamilton amplified slow shaking two to three times. A Wairoa North Fault earthquake gave 0.45 g, almost half of gravity, at Auckland's Mangatawhiri Dam.
- [Automatic precursor recognition and real-time forecasting of sudden explosive volcanic eruptions at Whakaari, New Zealand](https://ddempsey.github.io/papers/2020-dempsey-automatic-precursor-recognition-real-time/index.md): Dempsey DE, Cronin SJ, Mei S et al. (2020), *Nature Communications*. DOI 10.1038/s41467-020-17375-2. PDF: https://ddempsey.github.io/papers/2020-dempsey-automatic-precursor-recognition-real-time/dempsey2020-automatic-precursor-recognition.pdf Full text: https://ddempsey.github.io/papers/2020-dempsey-automatic-precursor-recognition-real-time/fulltext.md We trained a machine learning model on nine years of seismic tremor from one station at Whakaari. It recognised four-hour tremor bursts before most eruptions. In tests on eruptions withheld from its training, it warned of four of five eruptive episodes, including 17 hours before the fatal 2019 eruption.
- [Response of Induced Seismicity to Injection Rate Reduction: Models of Delay, Decay, Quiescence, Recovery, and Oklahoma](https://ddempsey.github.io/papers/2019-dempsey-response-induced-seismicity-injection-rate/index.md): Dempsey D, Riffault J (2019), *Water Resources Research*. DOI 10.1029/2018wr023587. PDF: https://ddempsey.github.io/papers/2019-dempsey-response-induced-seismicity-injection-rate/dempsey2019-response-induced-seismicity.pdf Full text: https://ddempsey.github.io/papers/2019-dempsey-response-induced-seismicity-injection-rate/fulltext.md We modelled how injection-triggered earthquakes respond to a cut in injection rate. The earthquake rate can fall by more than the cut and stop for a time before it partly recovers. For Western Oklahoma, our forecasts suggest the 2016 volume limit is inadequate.
- [Microseismicity Cloud Can Be Substantially Larger Than the Associated Stimulated Fracture Volume: The Case of the Paralana Enhanced Geothermal System](https://ddempsey.github.io/papers/2018-riffault-microseismicity-cloud-can-substantially-larger/index.md): Riffault J, Dempsey D, Karra S et al. (2018), *Journal of Geophysical Research: Solid Earth*. DOI 10.1029/2017jb015299. PDF: https://ddempsey.github.io/papers/2018-riffault-microseismicity-cloud-can-substantially-larger/riffault2018-microseismicity-cloud-can.pdf Full text: https://ddempsey.github.io/papers/2018-riffault-microseismicity-cloud-can-substantially-larger/fulltext.md During the 2011 Paralana geothermal stimulation in South Australia, earthquakes occurred up to 400 m from the well. Our inversion of the earthquake and well data suggests that permeability increased only within 40 m of it. For the best-fitting model, the stimulated volume was 0.4% of the seismically active volume.
- [Physics‐based forecasting of induced seismicity at Groningen gas field, the Netherlands](https://ddempsey.github.io/papers/2017-dempsey-physics-forecasting-induced-seismicity-groningen/index.md): Dempsey D, Suckale J (2017), *Geophysical Research Letters*. DOI 10.1002/2017gl073878. PDF: https://ddempsey.github.io/papers/2017-dempsey-physics-forecasting-induced-seismicity-groningen/dempsey2017-physics-forecasting-induced.pdf Full text: https://ddempsey.github.io/papers/2017-dempsey-physics-forecasting-induced-seismicity-groningen/fulltext.md We developed a physics-based model of the earthquakes caused by gas extraction at Groningen, calibrated it on about 600 recorded events, and forecast earthquakes from 2017 to 2024. Under each of three extraction rates, the largest event had a 5% chance of exceeding magnitude 4.0.
- [Simulation of the crystal growth of platelet sea ice with diffusive heat and mass transfer](https://ddempsey.github.io/papers/2015-wongpan-simulation-crystal-growth-platelet-sea/index.md): Wongpan P, Langhorne PJ, Dempsey DE et al. (2015), *Annals of Glaciology*. DOI 10.3189/2015aog69a777. PDF: https://ddempsey.github.io/papers/2015-wongpan-simulation-crystal-growth-platelet-sea/wongpan2015-simulation-crystal-growth.pdf Full text: https://ddempsey.github.io/papers/2015-wongpan-simulation-crystal-growth-platelet-sea/fulltext.md We simulated, crystal by crystal and in three dimensions, the loose layer of ice platelets that collects under Antarctic sea ice near ice shelves. In our model the layer is about 22% ice by volume, close to the 25 ± 6% estimated from field heat-flux measurements.
- [Collective properties of injection‐induced earthquake sequences: 2. Spatiotemporal evolution and magnitude frequency distributions](https://ddempsey.github.io/papers/2016-dempsey-collective-properties-injection-induced-earthquake-sequences/index.md): Dempsey D, Suckale J, Huang Y (2016), *Journal of Geophysical Research: Solid Earth*. DOI 10.1002/2015jb012551. PDF: https://ddempsey.github.io/papers/2016-dempsey-collective-properties-injection-induced-earthquake-sequences/dempsey2016-collective-properties-injection.pdf Full text: https://ddempsey.github.io/papers/2016-dempsey-collective-properties-injection-induced-earthquake-sequences/fulltext.md In our model, earthquakes triggered by rising fluid pressure include a higher proportion of small events than tectonic earthquakes. Pressure lowers the static strength of a fault faster than its residual strength. Modelling the 2010–2011 Guy-Greenbrier sequence in Arkansas, we estimated a fault permeability of 5 × 10⁻¹² m².
- [Collective properties of injection‐induced earthquake sequences: 1. Model description and directivity bias](https://ddempsey.github.io/papers/2016-dempsey-collective-properties-injection-induced-earthquake/index.md): Dempsey D, Suckale J (2016), *Journal of Geophysical Research: Solid Earth*. DOI 10.1002/2015jb012550. PDF: https://ddempsey.github.io/papers/2016-dempsey-collective-properties-injection-induced-earthquake/dempsey2016-collective-properties-injection.pdf Full text: https://ddempsey.github.io/papers/2016-dempsey-collective-properties-injection-induced-earthquake/fulltext.md We modelled large catalogues of earthquakes triggered by injecting fluid into a fault. In our model, these ruptures tended to propagate back towards the injection well, where high fluid pressure favours continued rupture. In the strongest case, a sample of three modelled ruptures was enough to detect this bias.
- [Hydraulic fracturing fluid migration in the subsurface: A review and expanded modeling results](https://ddempsey.github.io/papers/2015-birdsell-hydraulic-fracturing-fluid-migration-subsurface/index.md): Birdsell DT, Rajaram H, Dempsey D et al. (2015), *Water Resources Research*. DOI 10.1002/2015wr017810. PDF: https://ddempsey.github.io/papers/2015-birdsell-hydraulic-fracturing-fluid-migration-subsurface/birdsell2015-hydraulic-fracturing-fluid.pdf Full text: https://ddempsey.github.io/papers/2015-birdsell-hydraulic-fracturing-fluid-migration-subsurface/fulltext.md We modelled fracturing fluid injected into shale 1,500 m below a drinking water aquifer. In our model, no fluid reached the aquifer without a permeable pathway such as a fault or leaky well. Where a pathway existed, modelling well production and imbibition reduced the amount reaching the aquifer tenfold.
- [Numerical modeling of injection, stress and permeability enhancement during shear stimulation at the Desert Peak Enhanced Geothermal System](https://ddempsey.github.io/papers/2015-dempsey-numerical-modeling-injection-stress-permeability/index.md): Dempsey D, Kelkar S, Davatzes N et al. (2015), *International Journal of Rock Mechanics and Mining Sciences*. DOI 10.1016/j.ijrmms.2015.06.003. PDF: https://ddempsey.github.io/papers/2015-dempsey-numerical-modeling-injection-stress-permeability/dempsey2015-numerical-modeling-injection.pdf Full text: https://ddempsey.github.io/papers/2015-dempsey-numerical-modeling-injection-stress-permeability/fulltext.md In 2010, cold water injected below the pressure that opens fractures raised the injectivity of well 27-15 at Desert Peak by an order of magnitude. Our model suggests cooling, and the stresses it caused, kept fractures failing where overpressure was too low. Pressure was still needed to push water in.
- [Reducing uncertainty associated with CO2 injection and brine production in heterogeneous formations](https://ddempsey.github.io/papers/2015-dempsey-reducing-uncertainty-associated-co2-injection/index.md): Dempsey D, O’Malley D, Pawar R (2015), *International Journal of Greenhouse Gas Control*. DOI 10.1016/j.ijggc.2015.03.004. PDF: https://ddempsey.github.io/papers/2015-dempsey-reducing-uncertainty-associated-co2-injection/dempsey2015-reducing-uncertainty-associated.pdf Full text: https://ddempsey.github.io/papers/2015-dempsey-reducing-uncertainty-associated-co2-injection/fulltext.md When CO2 is injected while brine is pumped out nearby, unknown variations in rock permeability make the outcome hard to predict. In a synthetic reservoir, permeability measured at five wells narrowed 30-year prediction ranges by 40 to 72%. Pressure tests between wells narrowed two of these ranges further.
- [Passive injection: A strategy for mitigating reservoir pressurization, induced seismicity and brine migration in geologic CO2 storage](https://ddempsey.github.io/papers/2014-dempsey-passive-injection-strategy-mitigating-reservoir/index.md): Dempsey D, Kelkar S, Pawar R (2014), *International Journal of Greenhouse Gas Control*. DOI 10.1016/j.ijggc.2014.06.002. PDF: https://ddempsey.github.io/papers/2014-dempsey-passive-injection-strategy-mitigating-reservoir/dempsey2014-passive-injection-strategy.pdf Full text: https://ddempsey.github.io/papers/2014-dempsey-passive-injection-strategy-mitigating-reservoir/fulltext.md We propose passive injection, in which pumping brine out of a reservoir draws CO2 in without raising reservoir pressure. In our models, a closed reservoir 3 km deep stored up to about 4 million tonnes of CO2 a year, with about 1.7 tonnes of brine produced per tonne stored.
- [Insights into interconnections between the shallow and deep systems from a natural CO2 reservoir near Springerville, Arizona](https://ddempsey.github.io/papers/2014-keating-insights-interconnections-shallow-deep-systems/index.md): Keating E, Newell D, Dempsey D et al. (2014), *International Journal of Greenhouse Gas Control*. DOI 10.1016/j.ijggc.2014.03.009. PDF: https://ddempsey.github.io/papers/2014-keating-insights-interconnections-shallow-deep-systems/keating2014-insights-interconnections-shallow.pdf Full text: https://ddempsey.github.io/papers/2014-keating-insights-interconnections-shallow-deep-systems/fulltext.md At a natural CO2 reservoir in Arizona, a permeable fault likely connects the deep gas to a shallow aquifer. Water chemistry suggests that CO2 rises dissolved in saline water that also contains arsenic. In our simulations, most of the gas remains at depth despite the fault.
- [Modeling caprock bending stresses and their potential for induced seismicity during CO2 injection](https://ddempsey.github.io/papers/2014-dempsey-modeling-caprock-bending-stresses-their/index.md): Dempsey D, Kelkar S, Pawar R et al. (2014), *International Journal of Greenhouse Gas Control*. DOI 10.1016/j.ijggc.2014.01.005. PDF: https://ddempsey.github.io/papers/2014-dempsey-modeling-caprock-bending-stresses-their/dempsey2014-modeling-caprock-bending.pdf Full text: https://ddempsey.github.io/papers/2014-dempsey-modeling-caprock-bending-stresses-their/fulltext.md In our models, CO2 injection at overpressures of 5 to 10 MPa bent the caprock and induced stresses of about 1 to 2 MPa in it, outside the zone of raised fluid pressure. Such stresses would be enough to reactivate an undetected, well-oriented, critically stressed fault near the well.
- [Hydrological effects of dip‐slip fault rupture on a hydrothermal plume](https://ddempsey.github.io/papers/2013-dempsey-hydrological-effects-dip-slip-fault/index.md): Dempsey DE, Archer RA, Ellis SM et al. (2013), *Journal of Geophysical Research: Solid Earth*. DOI 10.1029/2012jb009395. PDF: https://ddempsey.github.io/papers/2013-dempsey-hydrological-effects-dip-slip-fault/dempsey2013-hydrological-effects-dip.pdf Full text: https://ddempsey.github.io/papers/2013-dempsey-hydrological-effects-dip-slip-fault/fulltext.md We modelled a hot-water plume beside a normal fault in New Zealand's Taupō Volcanic Zone. A modelled magnitude 5.7 earthquake tripled water outflow, but within 20 days the excess fell below 10% of natural outflow. Fault damage caused a lasting rise in flow and moved upflow away from the fault.
- [Delineation of catchment zones of geothermal systems in large‐scale rifted settings](https://ddempsey.github.io/papers/2012-dempsey-delineation-catchment-zones-geothermal-systems/index.md): Dempsey DE, Simmons SF, Archer RA et al. (2012), *Journal of Geophysical Research: Solid Earth*. DOI 10.1029/2012jb009515. PDF: https://ddempsey.github.io/papers/2012-dempsey-delineation-catchment-zones-geothermal-systems/dempsey2012-delineation-catchment-zones.pdf Full text: https://ddempsey.github.io/papers/2012-dempsey-delineation-catchment-zones-geothermal-systems/fulltext.md We modelled circulation in a rift like New Zealand's Taupō Volcanic Zone and traced water from ten modelled geothermal fields to where it entered the ground. Their catchments cover 70 to 500 km² and increase with field heat output. Most water spends 5,000 to 50,000 years underground.
- [Geometric properties of platelet ice crystals](https://ddempsey.github.io/papers/2012-dempsey-geometric-properties-platelet-ice-crystals/index.md): Dempsey DE, Langhorne PJ (2012), *Cold Regions Science and Technology*. DOI 10.1016/j.coldregions.2012.03.002. PDF: https://ddempsey.github.io/papers/2012-dempsey-geometric-properties-platelet-ice-crystals/dempsey2012-geometric-properties-platelet.pdf Full text: https://ddempsey.github.io/papers/2012-dempsey-geometric-properties-platelet-ice-crystals/fulltext.md We cut ten closely spaced slices from Antarctic sea ice and rebuilt its crystals in 3-D. For large, elongated grains, the outline in a photograph gave the horizontal direction of the c-axis with a standard deviation of 6°. Grain shape can also depend on the angle of the cut.
- [The role of frictional plasticity in the evolution of normal fault systems](https://ddempsey.github.io/papers/2012-dempsey-role-frictional-plasticity-evolution-normal/index.md): Dempsey DE, Ellis SM, Rowland JV et al. (2012), *Journal of Structural Geology*. DOI 10.1016/j.jsg.2012.03.001. PDF: https://ddempsey.github.io/papers/2012-dempsey-role-frictional-plasticity-evolution-normal/dempsey2012-role-frictional-plasticity.pdf Full text: https://ddempsey.github.io/papers/2012-dempsey-role-frictional-plasticity-evolution-normal/fulltext.md We modelled a single normal fault in a stretching crust. In our model the fault takes up about half of the stretching of the upper crust. Slow frictional shearing takes up the rest, mostly in the hanging wall, where we suggest new faults are favoured to form.
- [Modeling the effects of silica deposition and fault rupture on natural geothermal systems](https://ddempsey.github.io/papers/2012-dempsey-modeling-effects-silica-deposition-fault/index.md): Dempsey DE, Rowland JV, Zyvoloski GA et al. (2012), *Journal of Geophysical Research: Solid Earth*. DOI 10.1029/2012jb009218. PDF: https://ddempsey.github.io/papers/2012-dempsey-modeling-effects-silica-deposition-fault/dempsey2012-modeling-effects-silica.pdf Full text: https://ddempsey.github.io/papers/2012-dempsey-modeling-effects-silica-deposition-fault/fulltext.md We modelled a geothermal field in New Zealand's Taupō Volcanic Zone where cooling water deposits silica. Over 120,000 years, a low-permeability layer about 200 m thick formed at the surface. It diverted water sideways and warmed the reservoir. A fault rupturing the layer took at least 10,000 years to reseal.
- [Energetics of normal earthquakes on dip-slip faults](https://ddempsey.github.io/papers/2012-dempsey-energetics-normal-earthquakes-dip-slip/index.md): Dempsey D, Ellis S, Archer R et al. (2012), *Geology*. DOI 10.1130/g32643.1. PDF: https://ddempsey.github.io/papers/2012-dempsey-energetics-normal-earthquakes-dip-slip/dempsey2012-energetics-normal-earthquakes.pdf Full text: https://ddempsey.github.io/papers/2012-dempsey-energetics-normal-earthquakes-dip-slip/fulltext.md We modelled a normal fault in a stretching crust and quantified where energy is released and taken up during each earthquake. Stored elastic energy lifts the footwall. The hangingwall drops under gravity and compresses the crust. We suggest the energy for normal faulting comes from gravity and stored elastic energy.
- [Evolution of supercooling under coastal Antarctic sea ice during winter](https://ddempsey.github.io/papers/2011-leonard-evolution-supercooling-coastal-antarctic-sea/index.md): Leonard GH, Langhorne PJ, Williams MJM et al. (2011), *Antarctic Science*. DOI 10.1017/s0954102011000265.
- [Observation and modeling of platelet ice fabric in McMurdo Sound, Antarctica](https://ddempsey.github.io/papers/2010-dempsey-observation-modeling-platelet-ice-fabric/index.md): Dempsey DE, Langhorne PJ, Robinson NJ et al. (2010), *Journal of Geophysical Research: Oceans*. DOI 10.1029/2008jc005264. PDF: https://ddempsey.github.io/papers/2010-dempsey-observation-modeling-platelet-ice-fabric/dempsey2010-observation-modeling-platelet.pdf Full text: https://ddempsey.github.io/papers/2010-dempsey-observation-modeling-platelet-ice-fabric/fulltext.md Ice crystals that grow in supercooled water from beneath Antarctic ice shelves are frozen into sea ice. Using ice cores and a crystal growth model, we infer that western McMurdo Sound received a larger and more persistent supply of these crystals than the east in 2007.

## About the author

- [Home page](https://ddempsey.github.io/)
- [ORCID](https://orcid.org/0000-0003-2135-5129)
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- [GitHub](https://github.com/ddempsey)
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- [UC profile](https://profiles.canterbury.ac.nz/David-Dempsey)