4. febrúar 2020

Crustal movement on the Reykjanes peninsula

In recent weeks, ÍSOR has participated in measurements of crustal movements on the Reykjanes Peninsula in collaboration with the Institute of Earth Sciences, the Icelandic Meteorological Office and HS Orka. ÍSOR has been involved in InSAR (interferometric analysis of synthetic aperture radar images), earthquake and gravity measurements.

The course of events likely began in the wake of the two large earthquakes in the area of Grindavík on January 22nd 2020, when the University of Iceland's continuous GPS stations near Svartsengi showed signs of uplift west of Mt Þorbjörn. InSAR images from the 18th to the 24th of January 2020 also showed rapid uplift. Magma accumulation at several kilometers depth may be one reason for the uplift.

ÍSOR has for some time worked on InSAR measurements, and used data from the Sentinel-1 satellites from the European Space Agency (ESA). There are two Sentinel-1-tracks that cover the Reykjanes Peninsula, track 155 and track 16. As shown in the picture below, compiled data from January 20th to February 1st, the total maximum uplift is about 35 mm just west of Mt Þorbjörn, as stated in a report from the science advisory board of the civil protection of Iceland. Vincent Drouin, a geophysicist at ÍSOR, is in charge of processing the InSAR data.

Gravity measurements can be used to monitor changes do to mass changes in the Earth. By comparing the gravity measurements at the onset of the uplift and then later in the sequence of events, it can be investigated if the uplift is caused by gas, steam or magma. A geophysicist from ÍSOR acquired gravity measurements in the uplift area last week. Previous gravity measurements were done in 2014.
ÍSOR now operates 13 seismic stations on the Reykjanes Peninsula, owned by the Czech Academy of Science. Three of these stations are located in the vicinity of Mt Þorbjörn, and on January 27th experts from ÍSOR and the Icelandic Meteorological Office set up a real-time transmission of data from these stations to the Icelandic Meteorological Office. This is done to get more accurate locations of earthquake activity in the area. In addition, the Icelandic Meteorological Office operates several seismic stations on the Reykjanes Peninsula, one of which is located in Grindavík, near the source of the earthquake swarm.

Furthermore, ÍSOR is installing two new seismic stations west of Mt Þorbjörn for the Icelandic Meteorological Office, so a total of five seismic stations from ÍSOR will be located near the uplift.

A new InSAR-picture shows the vertical change from January 20th to February 1sth 2020, derived from analyzing the line-of-sight signal of two InSAR tracks.