Paleoseismic trenching, slip-rates and kinematics of a high-angle rift-transform junction, Húsavík, Iceland

Harrington, John
Jonsson, Sigurjon
Avşar, Ulaş
Klinger, Yann
We present results of recent fieldwork related to the Húsavík-Flatey Fault (HFF), a ~100 km dextral fault on the southern boundary of the Tjörnes Fracture Zone in North Iceland through which the Kolbinskey spreading ridge is connected with Iceland's Northern Volcanic Zone (NVZ). High-angle rift-transform junctions are rarely exposed on land, and tectonic studies of them are relatively rare (e.g. Mouslopoulou, et. al., 2007) - accordingly, the HFF provides an excellent field laboratory for the study of strike-slip terminations and oblique tectonics in general. The 20 km long onshore section of the fault is deflected by ~15° driving transtensional deformation and these segments display complex kinematics as the ~6.8 mm/yr of dextral motion, estimated from GPS measurements (Metzger, et al., 2012) interacts with the ~20 mm/yr extension of the Northern Rift Zone. Structural mapping of the on land section suggests a pattern of oblique deformation which gradually transforms a significant portion of the strike-slip into dip-slip motion as the fault moves closer to the NVZ. Although bedrock exposures are rare, due to glacial and tectonic erosion, the "Arctic desert" environment preserves Holocene-age deformation signals in geomorphology and soil profiles. Deflected drainages and soft-sediment deformations provide insight on kinematics and offset tephras and lavas provide Quaternary to mid-Holocene vertical slip-rate estimates on some structures in the fault zone. Preliminary results of paleoseismic trenching in a small basin on the western on land segment show evidence of multiple earthquakes, in a sequence that extends at least to the earliest Holocene. The established tephrachronology in the region is primarily used for chronology and we will perform Geotek MSCL on the trench walls. These records will also be correlated with sediment cores taken from Botsvatn (Lake), located only 1.5 km from the trench site.


Paleomagnetic evidence for upper plate response to a STEP fault, SW Anatolia
Kaymakcı, Nuretdin; ÖZKAPTAN, MURAT; Özacar, Atilla Arda; UZEL, BORA; SÖZBİLİR, HASAN (Elsevier BV, 2018-09-15)
Pliny-Strabo Trench is a Subduction Transform-Edge Propagator (STEP) Fault developed on the northern edge of the subducted African Oceanic Lithosphere. It connects the Aegean and Cyprian trenches in the Eastern Mediterranean convergent system. Although, deep geometry of the STEP fault and associated slab tear in mantle are imaged, its shallow vertical and lateral continuation in the crust and impact on the over-riding plate are still unknown. Thus, we have studied SW Anatolia, the candidate site where this ...
Paleoseismological record of the Hazar Lake along the East Anatolian Fault (Turkey)
Hubert-ferrari, Aurelia; Lamair, Laura; Hage, Sophie; Avşar, Ulaş; El Ouahabi, Meriam; Çağatay, Namık (2015-08-02)
The East Anatolian Fault (EAF) is a major left-lateral strike-slip fault accommodating with the conjugate North Anatolian Fault the westward extrusion of the Anatolian Plate away from the Arabia-Eurasia collision zone. The East Anatolian Fault ruptured over most of its length during the 19th century in a series of magnitude ~7 earthquakes. During the 20th century this fault was less active with only two events of magnitude greater than 6. This absence of large earthquakes has resulted in relatively little a...
Characteristics of the 2020 Samos earthquake (Aegean Sea) using seismic data
Kiratzi, Anastasia; Papazachos, Costas; Özacar, Atilla Arda; PINAR, ALİ; Kkallas, Charis; Sopaci, Eyup (2021-01-01)
The 30 October 2020 Samos earthquake (Mw 7.0) ruptured an east–west striking, north dipping normal fault located offshore the northern coast of Samos Island, previously inferred from the bathymetry and regional tectonics. This fault, reported in the fault-databases as the North Samos and/or Kaystrios Fault, ruptured with almost pure dip-slip motion, in a region where both active extension and strike-slip deformation coexist. Historical information for the area confirms that similar ~ Mw7 events had also occ...
Sedimentary Records of Past Earthquakes during the Last 2400 Years in Botnsvatn Lake on the Húsavík-Flatey Fault, North Iceland
Avşar, Ulaş; Geirsdttir, Aslaug; Thordarson, Thor; Miller, Gifford (2014-12-19)
The Húsavík-Flatey Fault (HFF), which is a part of the Tjörnes Fracture Zone (TFZ) in North Iceland, is a ~100 km-long dextral strike-slip fault. The fault has produced many magnitude 6-7 earthquakes in the past; however, the historical earthquake record in the region is mostly limited to the past 300 years. Almost 80% of the HFF is offshore. At the on-land part of the fault, glacial morphology and lack of well-developed fluvial systems limit the number of sites having faulting-related sedimentation, which ...
The Samos Island (Aegean Sea) M7.0 earthquake: analysis and engineering implications of strong motion data
Roumelioti, Zafeiria; Askan Gündoğan, Ayşegül; Sotiriadis, Dimitris; Gülerce, Zeynep; Melis, Nikolaos S.; Altindal, Abdullah; Akbaş, Burak; Sopaci, Eyüp; Karimzadeh, Shaghayegh; Kalogeras, Ioannis; Theodoulidis, Nikolaos; Konstantinidou, Kiriaki; Kale, Özkan; Margaris, Basil; Özacar, Atilla Arda (2021-01-01)
We present a dataset of 77 strong ground motion records within 200 km epicentral distance from the 30 October 2020, M7.0 Samos Island (Aegean Sea) earthquake, which affected Greece and Turkey. Accelerograms from National Networks of both countries have been merged into a single dataset, including metadata that have been uniformly derived using a common preliminary source model. Initial findings from the analysis and comparative examination of acceleration time histories, Fourier amplitude spectra and 5%-dam...
Citation Formats
J. Harrington, S. Jonsson, U. Avşar, and Y. Klinger, “Paleoseismic trenching, slip-rates and kinematics of a high-angle rift-transform junction, Húsavík, Iceland,” presented at the American Geophysical Union - Fall Meeting, (14 - 19 Aralık 2014), 2014, Accessed: 00, 2021. [Online]. Available: