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Sea Level Rise in New Zealand: The Effect of Vertical Land Motion on Century‐Long Tide Gauge Records in a Tectonically Active Region
Author(s) -
Denys Paul H.,
Beavan R. John,
Hannah John,
Pearson Chris F.,
Palmer Neville,
Denham Mike,
Hreinsdottir Sigrun
Publication year - 2020
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2019jb018055
Subject(s) - tide gauge , post glacial rebound , sea level , geology , global positioning system , geodesy , sea level rise , sea level change , physical geography , oceanography , climatology , seismology , geography , climate change , telecommunications , computer science
Abstract Historically tide gauge (TG) data have been used to estimate global sea level rise. Critical to the analysis of TG records is the assumption that the TG sites are stable and not affected by vertical land motion (VLM). We analyze century‐long TG records from New Zealand that have been affected by VLM due to both major and transient earthquake events at a regional level as well as local instabilities. Using combined GPS and precise leveling, we estimate relative VLM between the GPS and TG of up to 1 mm/year. Based on 15–20 years of GPS data, the effect of seismic activity and slow slip events has uplifted sites by up to 0.8 mm/year on average in Wellington and Dunedin. Updated estimates of long‐term relative sea level (RSL) at four New Zealand TGs, as well as an estimate of RSL at a new fifth TG (New Plymouth), are determined using data through 2013—an additional 13 years compared to the previous study. The VLM corrected RSL rates gives our best estimate absolute sea level of +1.45 ± 0.28 mm/year (1891−2013). It is important that absolute sea level derived from RSL rates include realistic estimates of VLM, especially at TG sites that are close to plate boundaries, located in seismically active regions, affected by glacial isostatic adjustment, land ice loss, or gas/oil/water extraction.