New Estimates of Present-Day Crustal/Land Motions in the British Isles Based on the BIGF Network

Abstract

In this study we present results from a recent reprocessing effort that included data from more than 120 continuous Global Positioning System (CGPS) stations in the British Isles for the period from 1997 to 2008. Not only was the CGPS network dramatically densified from previous investigations by the authors, it now also includes, for the first time, stations in Northern Ireland, providing new constraints on glacio-isostatic processes active in the region. In our processing strategy we apply a combination of re-analysed satellite orbit and Earth rotation products together with updated models for absolute satellite and receiver antenna phase centers, and for the computation of atmospheric delays. Our reference frame implementation uses a semi-global network of 37 stations, to align our daily position estimates, using a minimal constraints approach, to ITRF2005. This network uses a combination of current IGS reference frame stations plus additional IGS stations in order to provide similar network geometries throughout the complete time span. The derived horizontal and vertical station velocities are used to investigate present-day crustal/land motions in the British Isles. This first solution provides the basis for our contribution to the Working Group on Regional Dense Velocity Fields, 2007 -2011 of the International Association of Geodesy Subcommission 1.3 on Regional Reference Frames.

A Century of Sea Level Measurements at Newlyn, Southwest England

“…Figure 8 shows that MSL at Newlyn has risen significantly over the past century, at an average rate of 1.8 mm/year (with a standard error of approximately 0.1 mm/year; see discussion of sea level trend in this record in Rossiter (1967), Thompson (1980), Woodworth (1987), Woodworth et al (1999Woodworth et al ( , 2009a, Ara ujo and Pugh (2008), and Haigh et al (2009)). This rate is slightly more than in the northern parts of the UK where positive vertical land movement (emergence), primarily due to GIA, is more important (Shennan and Woodworth 1992;Shennan and Horton 2002;Bradley et al 2009;Teferle et al 2009;Woodworth et al 2009a;Hansen et al 2012). This rate is also similar to the global average over a similar period (Church et al 2014) although, because of the submergence at Newlyn discussed in the next section and based on evidence from other UK tide gauges, it is believed that the real (absolute) rate of sea level change during the 20th to 21st centuries in this region has been closer to 1.4 mm/ year (Woodworth et al 2009a).…”

A Multiple Algorithm Approach to the Analysis of GNSS Coordinate Time Series for Detecting Geohazards and Anomalies

“…The British Isles continuous GNSS Facility (BIGF) holds data and products dating back to 1997 (BIGF, n.d.; Hansen et al, 2012). For some stations, the long-term, daily GNSS coordinate time series have coordinate offsets, which can be due to documented changes (i.e., receiver and/or antenna equipment change) or undocumented changes.…”

State-of-the-art in studies of glacial isostatic adjustment for the British Isles: a literature review

“…Strictly speaking, direct geodetic measurement techniques, such as continuous GPS or InSAR, can only be used to acquire information about the net vertical glacial rebound process when all other vertical deformation effects can be neglected. However, the crustal uplift caused by GIA can be seen as the dominant process of VLM of the British Isles over a long-term period, so that the geodetic methods can be used as a good indicator of GIA (Bradley et al 2009;Hansen et al 2012).…”

“…Both aspects have a direct influence on relative sea-level (RSL) trends at the coast, which makes analysing and understanding the dynamics of GIA a critical task. The British GIA process, the effects of which are still prominent today, is mostly influenced by the disappearance of the Pleistocene British-Irish ice sheet and, to a lesser extent, by deglaciation effects of the Laurentide and Fennoscandian ice sheets (Hansen et al 2012). The last deglaciation of major global ice sheets began after the Last Glacial Maximum (P22 kyr BP) (Shakun & Carlson 2010) and lasted well into the early Holocene (P7 kyr BP) (Milne et al 2006).…”