Mechanical forcing of water pressure in a hydraulically isolated reach beneath Western Greenland's ablation zone
A suite of surface and basal measurements during and after borehole drilling is used to perform in situ investigation of the local basal drainage system and pressure forcing in western Greenland. Drill and borehole water temperature were monitored during borehole drilling, which was performed with d...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Cambridge University Press
2016-07-01
|
| Series: | Annals of Glaciology |
| Subjects: | |
| Online Access: | https://www.cambridge.org/core/product/identifier/S0260305516000057/type/journal_article |
| _version_ | 1811157294759542784 |
|---|---|
| author | Toby W. Meierbachtol Joel T. Harper Neil F. Humphrey Patrick J. Wright |
| author_facet | Toby W. Meierbachtol Joel T. Harper Neil F. Humphrey Patrick J. Wright |
| author_sort | Toby W. Meierbachtol |
| collection | DOAJ |
| description | A suite of surface and basal measurements during and after borehole drilling is used to perform in situ investigation of the local basal drainage system and pressure forcing in western Greenland. Drill and borehole water temperature were monitored during borehole drilling, which was performed with dyed hot water. After drilling, borehole water pressure and basal dye concentration were measured concurrently with positions in a GPS strain diamond at the surface. Water pressure exhibited diurnal changes in antiphase with velocity. Dye monitoring in the borehole revealed stagnant basal water for nearly 2 weeks. The interpretation of initial connection to an isolated basal cavity is corroborated by the thermal signature of borehole water during hot water drilling. Measurement-based estimates of cavity size are on the order of cubic meters, and analysis indicates that small changes in its volume could induce the observed pressure variations. It is found that longitudinal coupling effects are unable to force necessary volume changes at the site. Sliding-driven basal cavity opening and elastic uplift from load transfer are plausible mechanisms controlling pressure variations. Elastic uplift requires forcing from a hydraulically connected reach, which observations suggest must be relatively small and in close proximity to the isolated cavity. |
| first_indexed | 2024-04-10T05:04:53Z |
| format | Article |
| id | doaj.art-825e5d27b7bf4743825880d7aee9fcf0 |
| institution | Directory Open Access Journal |
| issn | 0260-3055 1727-5644 |
| language | English |
| last_indexed | 2024-04-10T05:04:53Z |
| publishDate | 2016-07-01 |
| publisher | Cambridge University Press |
| record_format | Article |
| series | Annals of Glaciology |
| spelling | doaj.art-825e5d27b7bf4743825880d7aee9fcf02023-03-09T12:27:29ZengCambridge University PressAnnals of Glaciology0260-30551727-56442016-07-0157627010.1017/aog.2016.5Mechanical forcing of water pressure in a hydraulically isolated reach beneath Western Greenland's ablation zoneToby W. Meierbachtol0Joel T. Harper1Neil F. Humphrey2Patrick J. Wright3Department of Geosciences, University of Montana, Missoula, MT, USA E-mail:Department of Geosciences, University of Montana, Missoula, MT, USA E-mail:Department of Geology and Geophysics, University of Wyoming, Laramie, WY, USADepartment of Geosciences, University of Montana, Missoula, MT, USA E-mail:A suite of surface and basal measurements during and after borehole drilling is used to perform in situ investigation of the local basal drainage system and pressure forcing in western Greenland. Drill and borehole water temperature were monitored during borehole drilling, which was performed with dyed hot water. After drilling, borehole water pressure and basal dye concentration were measured concurrently with positions in a GPS strain diamond at the surface. Water pressure exhibited diurnal changes in antiphase with velocity. Dye monitoring in the borehole revealed stagnant basal water for nearly 2 weeks. The interpretation of initial connection to an isolated basal cavity is corroborated by the thermal signature of borehole water during hot water drilling. Measurement-based estimates of cavity size are on the order of cubic meters, and analysis indicates that small changes in its volume could induce the observed pressure variations. It is found that longitudinal coupling effects are unable to force necessary volume changes at the site. Sliding-driven basal cavity opening and elastic uplift from load transfer are plausible mechanisms controlling pressure variations. Elastic uplift requires forcing from a hydraulically connected reach, which observations suggest must be relatively small and in close proximity to the isolated cavity.https://www.cambridge.org/core/product/identifier/S0260305516000057/type/journal_articleglacier hydrologysubglacial processes |
| spellingShingle | Toby W. Meierbachtol Joel T. Harper Neil F. Humphrey Patrick J. Wright Mechanical forcing of water pressure in a hydraulically isolated reach beneath Western Greenland's ablation zone Annals of Glaciology glacier hydrology subglacial processes |
| title | Mechanical forcing of water pressure in a hydraulically isolated reach beneath Western Greenland's ablation zone |
| title_full | Mechanical forcing of water pressure in a hydraulically isolated reach beneath Western Greenland's ablation zone |
| title_fullStr | Mechanical forcing of water pressure in a hydraulically isolated reach beneath Western Greenland's ablation zone |
| title_full_unstemmed | Mechanical forcing of water pressure in a hydraulically isolated reach beneath Western Greenland's ablation zone |
| title_short | Mechanical forcing of water pressure in a hydraulically isolated reach beneath Western Greenland's ablation zone |
| title_sort | mechanical forcing of water pressure in a hydraulically isolated reach beneath western greenland s ablation zone |
| topic | glacier hydrology subglacial processes |
| url | https://www.cambridge.org/core/product/identifier/S0260305516000057/type/journal_article |
| work_keys_str_mv | AT tobywmeierbachtol mechanicalforcingofwaterpressureinahydraulicallyisolatedreachbeneathwesterngreenlandsablationzone AT joeltharper mechanicalforcingofwaterpressureinahydraulicallyisolatedreachbeneathwesterngreenlandsablationzone AT neilfhumphrey mechanicalforcingofwaterpressureinahydraulicallyisolatedreachbeneathwesterngreenlandsablationzone AT patrickjwright mechanicalforcingofwaterpressureinahydraulicallyisolatedreachbeneathwesterngreenlandsablationzone |