Observed crustal uplift near the Southern Patagonian Icefield constrains improved viscoelastic Earth models

Thirty‒one GPS geodetic measurements of crustal uplift in southernmost South America determined extraordinarily high trend rates (> 35 mm/yr) in the north‒central part of the Southern Patagonian Icefield. These trends have a coherent pattern, motivating a refined viscoelastic glacial isostatic adjustment model to explain the observations. Two end‒member models provide good fits: both require a lithospheric thickness of 36.5 ± 5.3 km. However, one end‒member has a mantle viscosity near η =1.6 ×1018 Pa s and an ice collapse rate from the Little Ice Age (LIA) maximum comparable to a lowest recent estimate of 1995–2012 ice loss at about −11 Gt/yr. In contrast, the other end‒member has much larger viscosity: η = 8.0 ×1018 Pa s, half the post–LIA collapse rate, and a steadily rising loss rate in the twentieth century after AD 1943, reaching −25.9 Gt/yr during 1995–2012.

[1]  A. Rivera,et al.  Glacier fluctuations in extratropical South America during the past 1000 years , 2009 .

[2]  T. Herring,et al.  Steady-state laboratory flow laws alone fail to explain postseismic observations , 2010 .

[3]  Jeffrey T. Freymueller,et al.  Tectonic block motion and glacial isostatic adjustment in southeast Alaska and adjacent Canada constrained by GPS measurements , 2010 .

[4]  Axel Rülke,et al.  On-land ice loss and glacial isostatic adjustment at the drake passage: 2003-2009 , 2011 .

[5]  C. Carrigan,et al.  Small-Scale Convective Instability and Upper Mantle Viscosity Under California , 1993, Science.

[6]  W. Tad Pfeffer,et al.  Recent contributions of glaciers and ice caps to sea level rise , 2012, Nature.

[7]  J. Oerlemans.  Extracting a Climate Signal from 169 Glacier Records , 2005, Science.

[8]  Matthew E. Pritchard,et al.  Ice loss from the Southern Patagonian Ice Field, South America, between 2000 and 2012 , 2012 .

[9]  Yehuda Bock,et al.  Error analysis of continuous GPS position time series , 2004 .

[10]  M. Pérez‐Gussinyé,et al.  Spatial variations of the effective elastic thickness, Te, using multitaper spectral estimation and wavelet methods: Examples from synthetic data and application to South America , 2009 .

[11]  Xavier Collilieux,et al.  IGS08: the IGS realization of ITRF2008 , 2012, GPS Solutions.

[12]  Harald Schuh,et al.  Vienna mapping functions in VLBI analyses , 2004 .

[13]  J. Kouba.  Implementation and testing of the gridded Vienna Mapping Function 1 (VMF1) , 2008 .

[14]  Byron D. Tapley,et al.  Patagonia Icefield melting observed by Gravity Recovery and Climate Experiment (GRACE) , 2007 .

[15]  Wenke Sun,et al.  Reevaluation of the viscoelastic and elastic responses to the past and present-day ice changes in Southeast Alaska , 2011 .

[16]  L. Mervart,et al.  Bernese GPS Software Version 5.0 , 2007 .

[17]  M. R. van den Broeke,et al.  A Reconciled Estimate of Glacier Contributions to Sea Level Rise: 2003 to 2009 , 2013, Science.

[18]  Reinhard Dietrich,et al.  Rapid crustal uplift in Patagonia due to enhanced ice loss , 2010 .

[19]  Erik R. Ivins,et al.  Simple models for late Holocene and present-day Patagonian glacier fluctuations and predictions of a geodetically detectable isostatic response , 1999 .

[20]  Peter Steigenberger,et al.  Impact of higher‐order ionospheric terms on GPS estimates , 2005 .

[21]  Z. Martinec,et al.  Models of Active Glacial Isostasy Roofing Warm Subduction: Case of the South Patagonian Ice Field , 2007 .

[22]  Peter Steigenberger,et al.  Joint Reprocessing of GPS, GLONASS and SLR , 2013 .

[23]  Yehuda Bock,et al.  Southern California permanent GPS geodetic array: Error analysis of daily position estimates and site velocities , 1997 .

[24]  F. Pollitz,et al.  Temporal evolution of continental lithospheric strength in actively deforming regions , 2008 .

[25]  E. Ivins,et al.  Rapid viscoelastic uplift in southeast Alaska caused by post-Little Ice Age glacial retreat , 2005 .

[26]  A. Levander,et al.  Asthenospheric flow and lithospheric evolution near the Mendocino Triple Junction , 2012 .

[27]  W. Durham,et al.  Experimental constraints on the strength of the lithospheric mantle , 2010 .

[28]  Neil F. Glasser,et al.  Global sea-level contribution from the Patagonian Icefields since the Little Ice Age maximum , 2011 .

[29]  Fred F. Pollitz,et al.  A physical model for strain accumulation in the San Francisco Bay Region , 2004 .

[30]  Douglas S. Wilson,et al.  Continuing evolution of the Pacific–Juan de Fuca–North America slab window system—A trench–ridge–transform example from the Pacific Rim , 2009 .

[31]  A. Arendt,et al.  Mass balance in the Glacier Bay area of Alaska, USA, and British Columbia, Canada, 1995–2011, using airborne laser altimetry , 2013, Journal of Glaciology.

[32]  P. Skvarca,et al.  Recent Glacier Variations in the Southern Patagonia Icefield, South America , 1997 .

[33]  Eric Rignot,et al.  Contribution of the Patagonia Icefields of South America to Sea Level Rise , 2003, Science.

[34]  Erik R. Ivins,et al.  Bedrock response to Llanquihue Holocene and present‐day glaciation in southernmost South America , 2004 .