| 1. |
- Islam, Md. Tariqul, 1980, et al.
(författare)
-
Continuous subsidence in the Thingvellir rift graben, Iceland: Geodetic observations since 1967 compared to rheological models of plate spreading
- 2016
-
Ingår i: Journal of Geophysical Research - Solid Earth. - 0148-0227 .- 2156-2202. ; 121:1, s. 321-338
-
Tidskriftsartikel (refereegranskat)abstract
- North America-Eurasia relative plate motion across the Mid-Atlantic Ridge in south Iceland is partitioned between overlapping ridge segments, the Western Volcanic Zone (WVZ) and the Eastern Volcanic Zone. The Thingvellir graben, a 4.7km wide graben, lies along the central axis of the WVZ and has subsided >35m during the Holocene. An ~8km long leveling profile across the graben indicates a subsidence rate of ~1mmyr−1 from 1990 to 2007, relative to the first (westernmost) benchmark. Modeled GPS velocities from 1994 to 2003 estimate a spreading rate of 6.7±0.5mmyr−1 or 35% of the full plate motion rate and up to 6.0mmyr−1 subsidence. The combined geodetic observations show that the deformation zone is 10 times wider than the graben width. We utilize these geodetic observations to test the effects of ridge thermal structure on the kinematics across divergent boundaries. We apply a nonlinear rheology, thermomechanical model implemented in a finite element model. A 700°C isotherm is applied for the brittle to ductile transition in the crust, representing a dry olivine rheology. We adjust the depth of this isotherm to solve for the best fit model. The best fit model indicates that the 700°C isotherm is at 8km depth below the ridge axis, which results in an average thermal gradient of 87.5°Ckm−1 in the upper crust. The thermomechanical model predicts a subsidence rate of 4mmyr−1, comparable to our geodetic observations.
|
|
| 2. |
- Sturkell, Erik, 1962, et al.
(författare)
-
Katla and Eyjafjallajökull Volcanoes
- 2010
-
Ingår i: Developments in Quaternary Sciences, Vol. 13: The Mýrdalsjökull Ice Cap, Iceland. Glacial processes, sediments and landforms on an active volcano (Edited by Anders Schomacker, Johannes Krüger and Kurt H. Kjær). - : Elsevier Ltd. - 9780444530455 ; , s. 5-21
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The Katlavolcano is covered by the Mýrdalsjökull ice cap and is currently one of the most active volcanoes in Iceland. It has erupted twenty times the past 1,100 years. The neighbouring volcanoEyjafjallajökull has erupted twice, simultaneously with Katla. As glaciers cover both volcanoes, their eruptions are phreato-magmatic by nature. The volcanoes are located directly south of where surface expressions of the rift cease. Seismically, Katla is one of the most active volcanoes in Iceland, showing an annual cycle in activity, observed from at least 1960 and less pronounced since 2004. From 1999 to late 2004, GPS measurements revealed steady inflation of the volcano, showing uplift and outward horizontal displacement. Until 1990s, Eyjafjallajökull had been seismically quiet for several decades. Seismic activity there was high in 1994 and again in 1999, related to the emplacement of two intrusions.
|
|
| 3. |
|
|
| 4. |
- Allerstam, Fredrik, 1978, et al.
(författare)
-
Comparison between oxidation processes used to obtain the high inversion channel mobility in 4H-SiC MOSFETs
- 2007
-
Ingår i: Semiconductor Science and Technology. - : IOP Publishing. - 1361-6641 .- 0268-1242. ; 22:4, s. 307-311
-
Tidskriftsartikel (refereegranskat)abstract
- In this work two oxidation methods aimed at improving the silicon face 4H-SiC/SiO 2 interface are compared. One is an oxidation in N 2 O performed in a quartz tube using quartz sample holders and the other is a dry oxidation performed in an alumina tube using alumina sample holders. In n-type metal oxide semiconductor (MOS) capacitors the interface state density near the SiC conduction band edge is estimated using capacitance-voltage (C-V) and thermal dielectric relaxation current (TDRC) measurements. N-channel metal oxide semiconductor field effect transistors (MOSFETs) are characterized by current-voltage (I-V) techniques and the inversion channel mobility is extracted. It is shown that the high inversion channel mobility (154 cm 2 V -1 s -1 ) seen in samples oxidized using alumina correlates with a low interface trap density (3.6 × 10 11 cm -2 ). In the case of N 2 O oxidation the mobility is lower (24 cm 2 V -1 s -1 ) and the interface trap density is higher (1.6 × 10 12 cm -2 ). Room temperature C-V measurements are of limited use when studying traps near the conduction band edge in MOS structures while the TDRC measurement technique gives a better estimate of their density. © 2007 IOP Publishing Ltd.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
