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

<p>The 2014-2015 Holuhraun eruption was the largest eruption in Iceland in the last 230 years. After magma ascended below <!-- Gibt es ein Paper das belegt, dass Magmaaufstieg den Dike getriggert hat? Ich denke, das ist eher Spekulation. Vllt. wäre es besser einfach zu sagen, „From ice-covered Bardarbunga an about 2 week long EQ migration …“ -->the Bárðarbunga volcano’s icecap, an about 2 week long lateral migration of earthquakes was observed; later interpreted as dike formation in 4km to 6km depth<!-- Noch die Tiefe (formation [in 4-6km depth]) mit reinbringen? --><!-- Ja kannst du machen. -->. An eruption started on 29<sup>th</sup> and 31<sup>st</sup> 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<sup>th</sup> and 31<sup>st</sup> 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<!-- Bitte anpassen. --> (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.</p>

THE WAVE GEODYNAMIC IMPACT OF TECTONIC PROCESSES ON THE AMURIAN PLATE

The analysis of data on the migration of earthquakes and slow deformations from the Indo-Eurasian collision and the Western Pacific subduction zones is given, and the wave “geodynamic impact” of these tectonic processes on the Amurian plate and surrounding structures is shown. The interaction and a relative contribution of collision and subduction to the recent geodynamics of the Amurian plate are discussed. A scheme is constructed showing localizations of the slow strain wave manifestation in the areas of central and eastern Asia. The calculations are performed aimed at revealing a transverse migration of earthquakes (M ≥ 6.5) directed from the Japan and the Kuril-Kamchatka trenches toward the Asian continent during the time period from 1960 to 2015. The migration of earthquakes along the profile crossing Hokkaido Island occurs at velocities of 15 and 23 km/yr, whereas the migration velocity from the Kuril-Kamchatka Trench via Sakhalin Island is evaluated from 20 to 40 km/yr at different depths. We focus on an insufficient study of the influence of the Western Pacific subduction on the formation of the deformation field in continental Asia.

Seismotectonic features in the Northern Aegean sea

The analysis and processing of 1135 microearthquakes, recorded during the time period May 1993 – December 1994, indicated that the North Aegean Trough and the Trough of Skyros are the boundaries of, respectively, the NW and SE side of a tectonic Block in the shape of a trapezium, whose large base is the NW one. ΝW of the island of Lemnos, the North Aegean Trough changes direction from ENE-WSW to NE-SW. This point operates as a joint, on either side of which a differentiation of the areas is visible. In the SW of the troughs, two seismic gaps, which seem to be connected to a presently shaping channel of a NW-SE trend, were observed. The two southern branches of the North Anatolia Fault will constitute, in future, the northern and southern boundary of the Trough of Skyros. The migration of earthquakes in the North Aegean Sea follows a right lateral direction, however this direction changes to left lateral east of Chios Island.