Two earthquakes, one of magnitude 3.4 and another of 3.0, rattled the Reykjanes Peninsula last night, amidst a series of around 400 tremors. Geophysicist Páll Einarsson describes this seismic activity as a typical feature of the peninsula’s long geological history, marked by intermittent volcanic action.
Two earthquakes of magnitude 3.0
Two earthquakes reached a magnitude of three on the Reykjanes Peninsula last night, RÚV reports. The larger one, measuring 3.4, occurred approximately two kilometres north-northwest of Grindavík at 12.30 AM. Just after 5 AM, another quake, registering at 3.0, also occurred. Around 400 tremors have been detected since midnight, with seismic activity remaining similar to recent patterns.
The latest satellite data from the Icelandic Meteorological Office confirms the continued uplift near Þorbjörn. The same data show no signs of magma accumulation in Eldvörp or near Sýlingarfell, where seismic activity has been recorded in recent days.
Concurrent volcanic and seismic activity rare
In an interview with Mbl.is, published this morning, geophysicist Páll Einarsson provided insight into the ongoing geological drama unfolding on the Reykjanes Peninsula, including the seismic activities near Grindavík and the Blue Lagoon. “If we look at this from the beginning, what is happening on the Reykjanes Peninsula is part of a long history,” he stated.
Iceland’s dynamic landscape is shaped by its position straddling the boundary of diverging tectonic plates. This geological setting is the foundation for the sequence of events that characterise the Reykjanes Peninsula’s activity.
Páll further elaborated on the region’s distinctiveness: “This is a part of the tectonic plate boundaries of Iceland, and this particular section has the unique nature that volcanic activity comes into play for a relatively short period of time and then there is a pause.”
In geological terms, “short” is relative; in this context, it refers to active periods lasting 200-300 years, punctuated by 700-800 years of quiescence in magma activity. During these quieter times, the plate boundaries’ activity is primarily expressed through earthquakes.
Páll also noted the rarity of the Peninsula’s geological features: “These plate boundaries are somewhat unique in that this is a so-called oblique rift zone, with movement at an angle to the belt, which means that this belt has both volcanic and seismic activity, which is unusual.”
In contrast to most regions where belts are exclusively earthquake or volcanic zones, the Reykjanes Peninsula exhibits a rare combination of both. According to Páll, there are only two known examples of this phenomenon on a significant portion of the earth: the Reykjanes Peninsula and the oblique rift zone near Grímsey, both marked by concurrent volcanic and seismic activity.