Strain accumulation 1986-1992 across the Reykjanes Peninsula Plate Boundary, Iceland, determined from GPS measurements

1994 ◽  
Vol 21 (2) ◽  
pp. 125-128 ◽  
Author(s):  
Erik Sturkell ◽  
Freysteinn Sigmundsson ◽  
Páll Einarsson ◽  
Roger Bilham
Keyword(s):  
Plate Boundary ◽  
Strain Accumulation ◽  
Gps Measurements ◽  
Reykjanes Peninsula

scholarly journals Strain accumulation along an oblique plate boundary: the Reykjanes Peninsula, southwest Iceland

2008 ◽  
Vol 172 (2) ◽  
pp. 861-872 ◽  
Author(s):  
M. Keiding ◽  
T. Árnadóttir ◽  
E. Sturkell ◽  
H. Geirsson ◽  
B. Lund
Keyword(s):  
Plate Boundary ◽  
Strain Accumulation ◽  
Reykjanes Peninsula

scholarly journals Hydrologically Induced Karst Deformation: Insights From GPS Measurements in the Adria‐Eurasia Plate Boundary Zone

2018 ◽  
Vol 123 (5) ◽  
pp. 4413-4430 ◽  
Author(s):  
E. Serpelloni ◽  
F. Pintori ◽  
A. Gualandi ◽  
E. Scoccimarro ◽  
A. Cavaliere ◽  
...  
Keyword(s):  
Plate Boundary ◽  
Boundary Zone ◽  
Gps Measurements ◽  
Plate Boundary Zone

The possible role of magma and geothermal fluid in the episodic uplift cycles and intense seismicity beneath the Svartsengi high temperature geothermal field, Iceland 

2021 ◽  
Author(s):  
Ólafur Flóvenz ◽  
Rongjiang Wang ◽  
Gylfi Páll Hersir ◽  
Kristján Ágústsson ◽  
Magdalena Vassileva ◽  
...  
Keyword(s):  
High Temperature ◽  
Large Scale ◽  
Earthquake Swarm ◽  
Plate Boundary ◽  
Geothermal Field ◽  
Plate Boundaries ◽  
Clear Trend ◽  
Tectonic Event ◽  
Fibre Optics ◽  
Reykjanes Peninsula

<p>The highly productive high temperature geothermal fields in Iceland are located within active volcanic systems on the plate boundaries. When an earthquake swarm or an unusual surface uplift or subsidence occur, it is important to assess the hazards and whether the unrest is triggered or controlled by volcanic or anthropogenic processes, or a combination of both.</p><p>On January 22nd, 2020, a rapid, large-scale uplift (14 km x 12 km) started at the Svartsengi geothermal field on the plate boundary of the Reykjanes Peninsula, along with an intense earthquake swarm that began simultaneously about 3 km east of the centre of uplift. The centre of uplift was located about 1 km west of Mt. Thorbjörn, in the middle of the Svartsengi geothermal field, close to the reinjection wells. Over a period of 6 months, three such uplift cycles occurred, each lasting for several weeks and followed by periods of relatively rapid subsidence. The duration and timing of the uplift-subsidence cycles appears to follow a clear trend where the successive inflation episodes lasted longer but with lower inflation rate.</p><p>The centres of uplift and the deflation cycles are the same and remained stationary. The accompanied intense earthquake swarms migrated along the 40 km long oblique plate boundary of the Reykjanes Peninsula, demonstrating a major plate tectonic event. The maximum depth of earthquakes was close to 4.5 km directly above the centre of uplift but extending to 6-7 km in the surroundings where the maximum magnitudes reached M<sub>W</sub> 4.8.</p><p>A few weeks after the onset of the unrest, nine additional seismic stations were deployed to densify the local seismic network in place. In addition, complimentary data from an existing 21 km long fibre optics cable were used to monitor high-frequency linear strain rates. Both measures led to a significant improvement in the earthquake detection and location which predominantly occurred in swarms. Likewise, InSAR data analysis of temporal uplift cycles was performed, repeated gravity measurements at permanent sites were performed, and resistivity was remeasured at chosen sites.  </p><p>Multiple different elementary models were developed and tested to explain the cyclic excitation of the uplift, subsidence, and seismicity. While the individual unrest episodes might be controlled by possible magma intrusions into the lower crust, our favoured model explains the spatio-temporal pattern of ground uplift by the rise and diffusion of pore pressure in a 4-5 km deep geothermal aquifer. To distinguish between different models, we use multi-disciplinary geophysical datasets, such as deformation, seismicity, and gravity.</p>

The 2020 volcano-tectonic unrest at Reykjanes Peninsula, Iceland: stress triggering and reactivation of several volcanic systems

2021 ◽  
Author(s):  
Halldór Geirsson ◽  
Michelle Parks ◽  
Kristín Vogfjörd ◽  
Páll Einarsson ◽  
Freysteinn Sigmundsson ◽  
...  
Keyword(s):  
Earthquake Swarm ◽  
Plate Boundary ◽  
Tectonic Activity ◽  
Volcanic System ◽  
Multiple Systems ◽  
The North ◽  
Stress Changes ◽  
Uplift Rates ◽  
Source Models ◽  
Reykjanes Peninsula

<p>The Reykjanes Peninsula in south-west Iceland straddles the North-America - Eurasia plate boundary and hosts several active volcanic systems, including the Svartsengi volcanic system. The last eruption in this area took place around 1240 CE, with eruptive episodes recurring every 800-1000 years, affecting one volcanic system at a time, but spanning multiple systems  with activity spaced ~100 to 200 years. In January 2020, unrest was identified in Svartsengi, characterized by intense seismicity and inflation at a rate of 3-4 mm per day. This area is located within 5 km of several important infrastructures: a) the town of Grindavík; b) the Svartsengi geothermal power plant; c) and the Blue Lagoon geothermal spa, which had over a million annual visits before the Covid pandemy.</p><p> </p><p>Two continuously recording GNSS stations were installed in the Svartsengi geothermal area in 2013-2015 to monitor geothermally-induced subsidence.  Coinciding with the onset of an earthquake swarm starting on January 21 (M<4), uplift of about 3-4 mm/day was noticed in automated GNSS and InSAR results. The uplift rates in this first inflation phase decreased after January 31 and reverted to slight subsidence in early February. Interestingly, the most intense seismicity was offset from the uplift center by about 2-4 km to the southeast. Geodetic source models from the initial two weeks indicate the deformation is the result of a sill intrusion at a depth of about 4 km  with a volume change of approximately 3  million m<sup>3</sup>. The resulting stress changes from this intrusion act to increase seismicity at the sill edges, thus offering an explanation for why the seismicity is offset from the center of uplift. The location of the sill coincides roughly with a crustal volume with a high V<sub>p</sub>/V<sub>s</sub> ratio.</p><p> </p><p>Two more inflation-deflation episodes have occurred at Svartsengi in 2020 and the total uplift amounts to approximately 12 cm. Additionally, at least one inflation episode occurred in the Reykjanes system, in February 2020, and inflation started in the Krýsuvík system in mid-July 2020, culminating in a M5.6 earthquake on October 20. The Fagradalsfjall system, between Krýsuvík and Svartsengi, has shown high seismicity in 2020, but does not display detectable inflation nor deflation. Therefore, the volcano-tectonic activity in 2020 spans the entire western part of the Reykjanes Peninsula. The stress changes for each of these events are too small to explain the cross-system activity, hence we suggest the entire unrest is  by deep magma migration beneath the entire western Reykjanes Peninsula.  </p>

Advances in earthquake-swarms monitoring networks WEBNET and REYKJANET

2020 ◽  
Author(s):  
Jakub Klicpera ◽  
Jana Doubravová ◽  
Josef Horálek
Keyword(s):  
Main Shock ◽  
Plate Boundary ◽  
Earthquake Swarms ◽  
Monitoring Networks ◽  
Epicentral Zone ◽  
Epicentral Area ◽  
The North ◽  
Short Period ◽  
West Bohemia ◽  
Reykjanes Peninsula

<p>The IG CAS in cooperation with IRSM CAS operates two local seismic networks deployed to monitor the seismic swarms in West Bohemia/Vogtland, Czechia and Reykjanes Peninsula, Iceland. </p><p>WEBNET monitors the region of West Bohemia since 1991 developing from 4 short period stations to 24 broadband stations today. The seismoactive region West Bohemia/Vogtland lies in the border area between Czechia and Germany in the western part of Bohemian Massif. It is an intra-continental area with persistent swarm-like seismicity but rarely also main-shock after-shock sequences may occur. </p><p>REYKJANET local seismic network is situated in Reykjanes Peninsula on Southwest Iceland. The area is an onshore part of the mid-Atlantic plate boundary between the North America and Eurasia Plates. The seismic activity of Reykjanes peninsula is represented by typical main-shock after-shock sequences as well as earthquake swarms. The REYKJANET network was built in 2013 and it consists of 15 stations placed around the epicentral area.</p><p>Both networks have been substantially upgraded during the last years. In case of REYKJANET the replacement of old sensors and digitizers with new ones made the operation easier and ready for near future plan to stream the waveform files in real time. WEBNET network which was long years divided into two subnets – on-line permanent stations and off-line autonomous stations, was recently homogenized by eco-powering and 4G LTE data connecting of the off-line stations. Additonally, the micro network HORNET was deployed within the WEBNET epicentral zone to monitor Horka water dam.</p><p>Data from both above mentioned networks are automatically searched for seismic events by the neural-network-based detector designed by Doubravová et al. (2016, 2019) providing event list with completeness magnitude Mc=0 for REYKJANET and Mc=-0.5 for WEBNET. The main difference of sensitivity is given by different noise levels of the two networks.</p>

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