The first dating of strong Holocene earthquakes in Gorny Altai using long-term tree-ring chronologies

Abstract

We present the first results of application of long-term tree-ring chronologies for dating seismically triggered rockfalls and determining the upper age of Holocene rockfalls in southeastern Altai. Based on the results of seismic dendrochronological analysis, dating of penetrating wood injuries is proposed and tested, and the criterion for the distinguishing of seismically triggered rockfalls among slope processes of climatic nature is formulated. An earlier unknown strong earthquake of 1532 has been recognized; its traces are dated by the radiocarbon method. Based on the new data and calibration of earlier radiocarbon dates, the recurrence period of strong earthquakes in the southeastern Altai is refined.

Recurrence interval of strong earthquakes in the se Altai, Russia revealed by tree-ring analysis and radiocarbon dating

“…Utilizing discs and cores collected from trees, which were not affected by seismic shocks, the local 1154-years (AD 856-2009) TRC on Pinus sibirica Du Tour was built (Fig. 6), and verified by the "Jelo" tree-ring chronology (Agatova et al, 2014b). This local TRC has provided the dendrochronological dating of revealed wood penetrating injuries.…”

“…4 -A)) from the complex of earthquake triggered landslides in the Arydjan valley (Fig. 5) (Agatova et al, 2014b). A reactivated ancient fault, which laid the foundation of the head of Arydjan valley, formed main scarps of these landslides.…”

“…Developing presently as a single structure the Chagan-Uzun massif together with the western part of the Chuya intermountain depression is characterized by the largest rates of vertical movement 7.84-8.00 mm a -1 within the whole Chuya river basin (Rogozhin and Platonova, 2002). Numerous large seismically induced paleolandslides and rock-falls, that mark fault boundaries of the Chagan-Uzun massif, as well as smaller blocks of its inner structure, provide evidence for its high neotectonic activity and make it one of the major seismogenic structures in the region (Rogozhin and Platonova, 2002;Emanov et al, 2009 andAgatova et al, 2014b).…”

“…In our paleoseismogeological investigations within the SE Altai we complete existing radiocarbon dataset and for the first time utilize dendroseismological approach (Agatova et al, 2014b).…”

“…From 120 traumatic injuries of tree rings, three and more coincide into the years 1316, 1422, 1532 and 2003 (Agatova et al, 2014b). At the same time numerous wood penetrating injuries dated by AD 1532 are indicated for trees grown at both landslides and are displayed at various heights of tree trunks.…”