scholarly journals GPS measurements of regional deformation in Southern California: Some constraints on performance

Eos ◽  
1990 ◽  
Vol 71 (35) ◽  
pp. 1051 ◽  
Author(s):  
T. Dixon ◽  
G. Blewitt ◽  
K. Larson ◽  
D. Agnew ◽  
B. Hager ◽  
...  
Keyword(s):  
Southern California ◽  
Gps Measurements ◽  
Regional Deformation

scholarly journals CRUSTAL MOVEMENTS ALONG THE NW HELLENIC VOLCANIC ARC FROM DGPS MEASUREMENTS

2017 ◽  
Vol 43 (1) ◽  
pp. 331 ◽  
Author(s):  
E. Papageorgiou
Keyword(s):  
Reference Frame ◽  
Strain Rates ◽  
Differential Gps ◽  
Gps Measurements ◽  
Volcanic Arc ◽  
Crustal Movements ◽  
The North ◽  
Regional Deformation ◽  
North Western ◽  
Regional Tectonics

The north-western part of the Hellenic Volcanic Arc was studied by Differential GPS measurements in an attempt to investigate the regional deformation of the area. The GPS network involving stations in Athens, Aegina Island, Methana Peninsula and Soussaki was established in February 2006 and since then it was reoccupied twice. The GPS measurements were primarily referred to Worldfixed reference frame (ITRF2000) and then to Europe and Athens as well. The observed velocities for the overall three-year spanning period according to Athens station showed rates at the order of 7-10 mm/yr, while the directions of the displacements tend towards NNW to NNE. The results of the horizontal velocities with respect to Europe indicate rates of SW directions, exhibiting higher magnitudes (25-26±2mm/yr) in the western and southern part of the Saronikos Gulf than in its central part (20±7 mm/yr). The horizontal velocities with respect to ITRF2000 showed consistent SE directions with higher rates in Aegina (12±7 mm/yr) than in Soussaki and Methana (9±3 mm/yr). A kinematic interpretation based on velocity and strain rates is finally attempted on the basis of the regional tectonics in the Saronikos Gulf.

scholarly journals Creep along the Imperial Fault, southern California, from GPS measurements

2002 ◽  
Vol 107 (B10) ◽  
pp. ETG 12-1-ETG 12-13 ◽  
Author(s):  
Suzanne N. Lyons ◽  
Yehuda Bock ◽  
David T. Sandwell
Keyword(s):  
Southern California ◽  
Gps Measurements

Significant temporal changes in glacio isostatic adjustment in Iceland during the 1950s to present

2020 ◽  
Author(s):  
Halldór Geirsson ◽  
Gudmundur Valsson ◽  
Benedikt G. Ófeigsson ◽  
Erik Sturkell ◽  
Thora Arnadottir ◽  
...  
Keyword(s):  
Mass Balance ◽  
Vertical Motion ◽  
Mass Gain ◽  
Temporal Changes ◽  
Plate Motion ◽  
Glacier Mass Balance ◽  
Gps Measurements ◽  
Isostatic Adjustment ◽  
Regional Deformation ◽  
Uplift Rates

<p>The two most widespread geodynamic signals in Iceland are caused by glacio isostatic adjustment (GIA; up to 4.5 cm/yr vertical motion) and tectonic plate spreading (approximately 1.9 cm/yr horizontal motion). GPS measurements of crustal deformation started in Iceland in 1986 and annually tens to hundreds of benchmarks are re-measured. Many of these surveys are on local scales, but the ISNET campaigns in 1993, 2004, and 2016 are the only island-wide efforts. Continuous GPS (cGPS) measurements started in 1995 and now over 100 cGPS stations are running. The cGPS allows for excellent quantification of seasonal variations in position with amplitude up to several cm closest to the glaciers, driven mainly by seasonal snowload. Frequent observations also help to observe temporal changes in uplift rates and correlate to glacier mass balance. In recent years InSAR has been applied to obtain both local signals (e.g., due to glacial surges) and island-wide estimates of GIA and plate motion. However, InSAR does not work under the glaciers where we expect the largest uplift. Regular GPS measurements at several nunataks on Vatnajökull started in 2008 and provide the only intra-glacier GIA observations in Iceland. Going further backwards in time is a challenge and relies on local levelling where relative uplift rates can be compared to current relative uplift rates to infer the temporal evolution.</p><p>During 1993-2004 the average observed uplift rates reached at most around 2 cm/yr and were likely at its lowest in the early 1990s, lower than during 1959-1991. During 2004-2010 the uplift rates increased on average by 70% compared to the previous time period. A thin layer of ash from the 2010 Eyjafjallajökull eruption enhanced the melting rates and is clearly seen as enhanced uplift rates during 2010-2012. Until 2014 the uplift rates remained high. In 2014 the average uplift rates lowered by around 20%. Comparable changes are observed in the horizontal deformation field. Overall, recent changes in GIA broadly follow changes in climate and mass balance. The first part of the 90s was cold and glaciers in Iceland were overall in equilibrium or gaining a bit of mass. After 1995 the glaciers started losing considerable mass every year. From 2011 the mass loss decreased; in 2015 there was a net mass gain, and in 2017 and 2018 the mass balance was close to equilibrium. The highly variable deformation rates call for a re-evaluation of the current GIA models, working towards a time-dependent response that can be applied to regional deformation studies.</p>

The Effects of Presentation on Noise and Dental Appliances on Speech

1981 ◽  
Vol 24 (1) ◽  
pp. 151-151
Author(s):  
Lillian Glass ◽  
Sharon R. Garber ◽  
T. Michael Speidel ◽  
Gerald M. Siegel ◽  
Edward Miller
Keyword(s):  
Southern California ◽  
University Of Southern California ◽  
University Of Minnesota ◽  
School Of Medicine ◽  
Southern California School ◽  
School Of Dentistry ◽  
The University

An omission in the Table of Contents, December JSHR, has occurred. Lillian Glass, Ph.D., at the University of Southern California School of Medicine and School of Dentistry, was a co-author of the article "The Effects of Presentation on Noise and Dental Appliances on Speech" along with Sharon R. Garber, T. Michael Speidel, Gerald M. Siegel, and Edward Miller of the University of Minnesota, Minneapolis.

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