Source parameters of the Sarez-Pamir earthquake of 1911 February 18

Abstract

The M s ∼ 7.7 Sarez-Pamir earthquake of 1911 February 18 is the largest instrumentally recorded earthquake in the Pamir region. It triggered one of the largest landslides of the past century, building a giant natural dam and forming Lake Sarez. As for many strong earthquakes from that time, information about source parameters of the Sarez-Pamir earthquake is limited due to the sparse observations. Here, we present the analysis of analogue seismic records of the Sarez-Pamir earthquake. We have collected, scanned and digitized 26 seismic records from 13 stations worldwide to relocate the epicentre and determine the event's depth (∼26 km) and magnitude (m B 7.3 and M s 7.7). The unusually good quality of the digitized waveforms allowed their modelling, revealing an NE-striking sinistral strike-slip focal mechanism in accordance with regional tectonics. The shallow depth and magnitude (M w 7.3) of the earthquake were confirmed. Additionally, we investigated the possible contribution of the landslide to the waveforms and present an alternative source model assuming the landslide and earthquake occurred in close sequence.

The 2015 Mw7.2 Sarez Strike‐Slip Earthquake in the Pamir Interior: Response to the Underthrusting of India's Western Promontory

“…The relatively low strain rates in the central Pamir are hardly enough to reload the same fault in slightly more than 100 years: Compared to average GPS rates in the West Pamir, the East Pamir block exhibits 5 ± 2 mm/yr of increased NNE motion (Figure S11). S ‐ P phase arrival times measured at European stations are about 6 s less for the 1911 event compared to the 2015 event (Kulikova et al, ), indicating that they did not occur at the same location but that the 1911 event was closer to Europe. From a stress perspective, a location of the 1911 event contiguous north or south of the 2015 rupture would be most plausible, albeit less consistent with intensities of shaking and travel times.…”

“…Close‐up of the Sarez‐Karakul fault system including shallow seismicity (2008–2010 and 2012–2014, purple) (Kufner et al, ; Sippl, Schurr, Yuan, et al, ), main active faults in brown, focal mechanisms of selected earthquakes in pink (Schurr et al, ), the 1911 event in green (Ambraseys & Bilham, ; Bindi et al, ; Kulikova et al, ; Storchak et al, ), and the 2015 earthquake in red (USGS, ). The color‐coded line represents the modeled slip of the 2015 earthquake in the upper 2.5 km of the crust (only slip >0.5 m is shown).…”

“…This earthquake triggered a massive rockfall forming the Earth's highest dam, the Usoi dam, which confines today's 17 km 3 Lake Sarez (Ischuk, ; Schuster & Alford, ). The proximity and similarities in mechanism and size of the two earthquakes (Kulikova et al, ) are striking and the question arises if the 2015 event repeated the 1911 earthquake. Herein, we present an analysis of fault location, geometry, slip distribution, and amplitude of the 2015 earthquake based on space‐geodetic and field data.…”

“…(a) Tectonic setting of the Pamir with main active faults (brown) (Schurr et al, ), microseismicity (2008–2010 and 2012–2014) (Kufner et al, ; Sippl, Schurr, Yuan, et al, ), instrumentally recorded seismicity (1900–2012) above magnitude 5 (Storchak et al, ), and GPS rates of Ischuk et al () (red) and Zubovich et al () (green) in a stable Eurasia reference frame. The focal mechanisms indicate the locations and mechanisms for the 1911 (green) (Kulikova et al, ) and the 2015 (red) earthquake (USGS, ). A‐MFS: Aksu‐Murgab fault system, DF: Darvaz fault, KF: Karakorum fault system, KST: Kongur Shan‐Tashkorgan normal fault system, MR: Muzkol range, OR: Officers range, PTS: Pamir thrust system, SKFS: Sarez‐Karakul fault system.…”

Active tectonics, earthquakes and palaeoseismicity in slowly deforming continents

“…Modern analyses have been performed on some historic seismograms (e.g. Schlupp & Cisternas 2007;Kulikova & Krüger 2015;Kulikova et al 2016), yielding estimates of magnitude, focal mechanism or other source parameters. Interestingly, a new archive, reaching a few more centuries back, may be available.…”