Updates on volcanic activity (Smithsonian)
The Smithsonian/USGS Weekly Volcanic Activity Report provides information about global volcanism on a weekly basis. Latest Reykjanes report has been published on 15 Nov 2023 11:37.
The Icelandic Meteorological Office (IMO) reported increased seismic activity and deformation caused by a magmatic dike intrusion with no surface eruption through 14 November in the eastern Reykjanes-Svartsengi volcanic system on the Reykjanes Peninsula, W of the Fagradalsfjall fissure system that produced lava flows during eruptions over the previous three years. Due to increased local seismicity recorded since 25 October, the onset of ground inflation on 27 October, geophysical models of the magma intrusion, and uncertainties associated with a possible eruption site, the National Police Commissioner evacuated approximately 4,000 residents from the coastal town of Grindav?k on 10 November. IMO is responsible for volcano monitoring in Iceland, in coordination with scientists from the University of Iceland, and the Department of Civil Protection and Emergency Management.
An intense seismic swarm occurred during the night of 8-9 November; seven earthquakes (max. M 4.0) were centered in the area from Eldv?rp to E of S?lingarfell, with the largest measuring M 4.8 at 0046 on the 9th located W of Mt. ?orbj?rn. Ground uplift continued to be detected in GPS and satellite data, with the highest rates occurring NW of ?orbj?rn. Geophysical models estimated the depth to the top of the intrusion was estimated to be ~800 m. On 10 November an intense seismic swarm at a depth of 5 km began near Sundhnj?kagigar, NE of ?orbj?rn, around 0700 and increased further at 1500. More than 800 earthquakes were detected on 11 November at depths of 3-3.5 km and seismic activity migrated S towards Grindav?k. IMO attributed the shallow seismicity to the intrusion extending from St?ra-Sk?gsfell, ~6 km NNE of Grindav?k, to beneath Grindav?k, and offshore. Data acquired from satellite radar showed a graben-like are of deflation cutting through Grindav?k. Analysis of COSMO-SkyMed (CSK) radar interferogram data from 3-11 November indicated that the intrusion was about 15 km long at a minimum depth of less than 1 km.
Geodetic models on 12 November showed that an area of inflation was located 3.5 km N of Grindav?k, close to Sundhn?kur. Approximately 1,000 earthquakes, less than M 3.0, were detected N of Grindav?k at 3-5 km depths between 0000 and 1230 on 12 November. On 13 November, the size and intensity of earthquakes decreased, when approximately 900 earthquakes were detected at depths of 2-5 km between 0000 and 1620 in the area between Sundhn?kur and Grindav?k. During 12-13 November, calculations estimated that the magma inflow to the intrusion was 75 cubic meters per second. Between 0000 and 1240 on 14 November, 700 earthquakes occurred at depths of 3-5 km along the intrusion; the largest was M 3.1. After IMO installed two Differential Optical Absorption Spectrometers (DOAS, remote sensing gas instruments) on H?safell, one of them detected SO2 at the graben-like feature between Sundhn?kag?gar and Grindav?k, but the source was unknown. Additional GPS stations have also been installed to monitor deformation.
Sources: Almannavarnadeild r?kisl?greglustj?ra (National Commissioner of the Icelandic Police and Department of Civil Protection and Emergency Management),Icelandic Meteorological Office (IMO),Icelandic National Broadcasting Service (RUV)
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