The Neftegorsk, Sakhalin Island, earthquake of 27 May 1995

Abstract

Past seismic catastrophes were unknown in Sakhalin Island before 1995 except those suggested from findings of paleoseismodislocations. The first time that dwellers have experienced such a catastrophe in the Sakhalin Island history was on 27 May 1995. The devastating Neftegorsk earthquake occurred in Northern Sakhalin (cp = 52.8" north; h = 143.2' east; H = 18 km; M, = 7.2), killed almost 2000 people in the small city of Neftegorsk, caused damage and destruction of buildings, bridges, railways and roads, breakage of oil and gas pipelines, electric and communication lines, and was accompanied by large-scale surface phenomena within a source area. It was felt all over the Sakhalin Island, as well as over the closest part of the Eurasian continent. Surface fracturing was the most impressive effect of the Neftegorsk earthquake. The 37-km long, right-lateral strike-slip fault, with a strike of north 15" east and a horizontal displacement up to a maximum of 8m, has been observed from Taxon Mountain at the south to the junction of the Cadylanye and Keniga Rivers at the north. According to the results of a detailed geological survey and study of the aftershocks, the total extent of the source area was -80 km. Various secondary phenomena have been observed at the Earth's surface, such as landslides, falls, soil liquefaction, mud volcanoes etc. The earthquake was followed by hundreds of aftershocks within the following 1-2 months. Spatially, the earthquake fault coincides with the pre-existing Upper Piltun fault, known earlier from geological studies. Recent high activity of the latter fault has been recognized only after the Neftegorsk event because of findings of traces of significant past dislocations within the fault zone. From a tectonic viewpoint it can be suggested that the Upper Piltun fault is a Riedel-type shear fracture located between two main regional faults: the Gyrgylanye-Dagy fault at the west and the Piltun-Ekhaby fault at the east. Therefore, its present activity, expressed by the destructive Neftegorsk earthquake, seems to be explained by a long strain accumulation within a broad zone of regional right-lateral shear faulting.

Geodynamic implications of paleomagnetic data from Tertiary sediments in Sakhalin, Russia (NW Pacific)

“…On the basis of earthquake slip data (e.g., the 1995 Neftegorsk earthquake [ Ivashchenko et al , 1997], which indicates a transform boundary in northern Sakhalin), Seno et al [1996] suggested that the Okhotsk Sea Plate currently rotates clockwise about a pole in the northern Okhotsk Sea. This gives a solution that takes into account thrust deformation in southern Sakhalin, which the “extrusion” model [ Jolivet et al , 1994; Worrall et al , 1996] fails to do.…”

“…(b) Geological map of Sakhalin. Compiled from various sources [ Vereshchagin , 1969; Rozhdestvenskiy , 1982; Kharakhinov et al , 1985; Fournier et al , 1994; Ivashchenko et al , 1997]. (c) Map of major suture zones and tectonostratigraphic units in southeastern Russia.…”

The sedimentary and tectonic evolution of the Amur River and North Sakhalin Basin: new evidence from seismic stratigraphy and Neogene–Recent sediment budgets

“…Several factors suggest that dextral displacement on the Sakhalin‐Hokkaido Shear Zone is the primary reason for the dislocation of the palaeo‐Amur depocentre. Firstly, the Sakhalin‐Hokkaido Shear Zone is seismically active today, as seen in the 1995 Neftegorsk earthquake (Ivashchenko et al ., ). The dextral strike‐slip component of relative motion between these two plates is measured using GPS velocities at 2 mm year −1 (Apel et al ., ), which is consistent with Pleistocene geomorphic slip rates measured from individual fault strands of the Sakhalin‐Hokkaido Shear Zone (Nicholson et al ., ).…”

Possible sources of hydrothermal activity and mud volcanism in southern Sakhalin inferred from local earthquake seismic tomography

“…The continuous seismic background and occurrence of strong earthquakes demonstrate that tectonic processes are still ongoing in the crust below Sakhalin and the surrounding offshore areas [e.g., Zlobin, 2005;Tichonov and Lomtev, 2014]. The strongest recorded earthquake in this region, with a magnitude of M W 7.6, occurred on 28 May 1995 in the northern part of Sakhalin [e.g., Rogozhin, 1996;Ivashchenko et al, 1997]. In only 17 s, it caused sufficient damage to completely destroy the city of Neftegorsk and kill 2040 people (almost two-thirds of the city's population).…”

“…Many authors have suggested that the north-south-oriented lineament throughout Hokkaido and Sakhalin represents a fault zone with a predominant dextral strike-slip component [e.g., Fournier et al, 1994]. The mechanisms of pure strike-slip displacement during the catastrophic Neftegorsk earthquake with a magnitude of M W 7.6, occurred on 28 May 1995 in the northern part of Sakhalin seem to support this model [e.g., Rogozhin, 1996;Ivashchenko et al, 1997;Katsumata et al, 2004]. However, a series of recent earthquakes in the southern part of Sakhalin, including the M W 6.2 Nevelsk earthquake, reveal almost pure thrust deformation [Konovalov et al, 2015].…”