Linking lava morphologies to effusion rates for the 2014–2015 Holuhraun lava flow field, Iceland

Determining the parameters that control fissure-fed lava morphologies is critical for reconstructing the complex emplacement histories of eruptions on Earth and other planetary bodies. We used a geomorphological map of the 2014–2015 Holuhraun lava flow field, in combination with new constraints on lava emplacement chronology and two independently derived time-averaged discharge rate (TADR) data sets, to analyze correlations between lava morphology and effusion rate. Results show that lava morphologies are dominantly controlled by effusion rate at the vent during the early phases of the eruption and by lava transport processes as the system evolves. Initially, TADR and its variance, which reflect pulsation in the lava supply rate from the vent, directly affect lava emplacement styles. However, as the eruption progresses, the lava transport system exerts a stronger control with channels and ponds that can either dampen variation in local effusion rate or create surges during sudden drainage events. The Holuhraun eruption predominantly produced rubbly lava in its earlier eruption phases and transitioned into the production of spiny lava toward the end of the eruption. However, a drop of TADR during the first phase of the eruption correlates with a decrease in rubbly lava formation and an increase in spiny lava production. This suggests that a change in effusion rate caused the observed transition in lava type. Our findings show that rubbly lava is formed under relatively high local effusion rates with pulsating supply conditions, whereas spiny lava is formed under lower local effusion rates and steadier supply.

Supplemental Material: Linking lava morphologies to effusion rates for the 2014–2015 Holuhraun lava flow field, Iceland

Details about previous established links between emplacement conditions and lava types, data and methods, additional correlation results, and limitations.<br>

Supplemental Material: Linking lava morphologies to effusion rates for the 2014–2015 Holuhraun lava flow field, Iceland

Details about previous established links between emplacement conditions and lava types, data and methods, additional correlation results, and limitations.<br>

Paleomagnetic dating of prehistoric lava flows from the urban district of Catania (Etna volcano, Italy)

Determining the ages of past eruptions of active volcanoes whose slopes were historically inhabited is vitally important for investigating the relationships between eruptive phenomena and human settlements. During its almost three-millennia-long history, Catania—the biggest city lying at the toe of Etna volcano—was directly impacted only once by the huge lava flow emplaced during the A.D. 1669 Etna flank eruption. However, other lava flows reached the present-day Catania urban district in prehistoric ages before the founding of the city in Greek times (729/728 B.C., i.e., 2679/2678 yr B.P.). In this work, the Holocene lava flows of Barriera del Bosco, Larmisi, and San Giovanni Galermo, which are exposed in the Catania urban district, were paleomagnetically investigated at 12 sites (120 oriented cores). Paleomagnetic dating was obtained by comparing flow-mean paleomagnetic directions to updated geomagnetic reference models for the Holocene. The Barriera del Bosco flow turns out to represent the oldest eruptive event and is paleomagnetically dated to the 11,234−10,941 yr B.P. and 8395−8236 yr B.P. age intervals. The mean paleomagnetic directions from the San Giovanni Galermo and Larmisi flows overlap when statistical uncertainties are considered. This datum, along with geologic, geochemical, and petrologic evidence, implies that the two lava flows can be considered as parts of a single lava field that erupted in a narrow time window between 5494 yr B.P. and 5387 yr B.P. The emplacement of such a huge lava flow field may have buried several Neolithic settlements, which would thus explain the scarce occurrence of archaeological sites of that age found below the town of Catania.

Analyzing the tremor of the Holuhraun eruption 2014-2015 using tremor modelling

&lt;p&gt;The 2014-2015 Holuhraun eruption was the largest eruption in Iceland in the last 230 years. After magma ascended below &lt;!-- Gibt es ein Paper das belegt, dass Magmaaufstieg den Dike getriggert hat? Ich denke, das ist eher Spekulation. Vllt. w&amp;#228;re es besser einfach zu sagen, &amp;#8222;From ice-covered Bardarbunga an about 2 week long EQ migration &amp;#8230;&amp;#8220; --&gt;the Ba&amp;#769;r&amp;#240;arbunga volcano&amp;#8217;s icecap, an about 2 week long lateral migration of earthquakes was observed; later interpreted as dike formation in 4km to 6km depth&lt;!-- Noch die Tiefe (formation [in 4-6km depth]) mit reinbringen? --&gt;&lt;!-- Ja kannst du machen. --&gt;. An eruption started on 29&lt;sup&gt;th&lt;/sup&gt; and 31&lt;sup&gt;st&lt;/sup&gt; of August 2014 at Holuhraun. During dike formation and eruption a long-lasting seismic signal called tremor was recorded by seismometers in the area. Eruptive tremor emerged with the onset of the eruptions on 29&lt;sup&gt;th&lt;/sup&gt; and 31&lt;sup&gt;st&lt;/sup&gt; of August . Tremor sources were located and interpreted in the context of the fissure and the lava flow field. However, a complete geophysical model to explain these is missing. Our starting point is the model on tremor generation based on conduit wall vibrations exited by laminar flow&lt;!-- Bitte anpassen. --&gt; (B. Julian 1994) to replicate the observed tremor signals. We performed a grid search and compare it with other models. In the range of rock parameter tolerance, we present implied characteristics of frequency and amplitude of the signals, if the Julian model were used as explanation for the tremor signals.&lt;/p&gt;

Lava flow hazard of the 2018 Etna eruption: What happened and what could happen

&lt;p&gt;On 24 December 2018 a flank eruption started on Etna from an eruptive fissure opened on the eastern side of the New Southeast Crater (NCSE) at about 3,100 m asl, which in few minutes, propagated to the south-east, overcoming the edge of the western wall of the Valle del Bove (VdB), reaching an altitude of 2,400 m asl and a total length of about 2 km. The eruption, which lasted only three days, produced lava flows from different vents along the eruptive fissure that reached a distance of about 4.2 km and covered an area of about 1 km2. The satellite monitoring of the 2018 Etna eruption was performed using the HOTSAT system using mid and thermal infrared data acquired by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI), which provided minimum and maximum estimates for the lava thermal flux, the effusion rate and the lava volume. The SEVIRI-derived effusion rate estimates were used as input of the MAGFLOW model to simulate the actual lava flow field, obtaining a very good fit. We also simulated different eruptive scenarios assuming the lava emission wouldn&amp;#8217;t run out in only three days to forecast if, when and how the lava flow could reach the inhabited areas, causing possible significant damage.&amp;#160;&lt;/p&gt;