The Sarez-Pamir Earthquake and Landslide of 18 February 1911

Abstract

NEWS OF SHAKING AND EXPLORATIONS OF THE EPICENTRAL REGION ! Figure 2. Pamir and surroundings with locations discussed in text. Isoseismal contours (MSK) dashed. The earthquake occurred in winter in a sparsely inhabited part of the Pamir Mountains in Tajikistan (Figure 2), then in the Russian empire, where the mean elevation is 4.4 km amid 2.8 km of local relief. The population density of the region in 1911 is not known, but about 20 years later it was less than 1/km , as compared with 3/km today. The region was inhabited mostly by nomads in transit, rather than by a sedentary population, who migrated with the seasons between the valley floor and higher slopes, maintaining one or two refuges at different levels for the different seasons. They lived in their 2 2 winter pastures (kishlak) and their summer highland pastures (yaylak), mostly in yurts (dwellings made of a wooden lattice-frame covered with felt), which are fully earthquake proof (Figure 3C). They pastured their animals at different elevations in different seasons. More substantial structures using adobe construction were found in villages sited on alluvial fans near the rivers or higher up on gentle slopes. Russian military and administrative posts used mud brick and stone dwellings. Roads were simple tracks for pack animals, mostly skirting steep, unstable slopes or passing through narrow, short tunnels dug through mountainsides. The damage and loss of life caused by the earthquake were chiefly due to rock-and landslides that killed livestock, spoiled the few patches of cultivated land, and destroyed vital tracks and mountain passes, isolating the region. Many of the few sedentary inhabitants eventually migrated to neighboring Chinese territory. ! Figure 3. Photo montage of contemporary photographs of the Usoy landslide and its approaches and maps by Shpilko (1914, 1915), Stein (1928), and Chuenko (1936). (A) The natural dam of Usoy thrown across the Bartang River. In the background is the scarp left after the collapse of the south face of the mountain. Clouds of dust raised by rock falls were seen on higher slopes in August 1915. The crest of the dam is on the left in the foreground, with the western end of Lake Sarez on the right (Stein 1933, Plate 373). (B) One of the rockslides followed by ice flow (Preobrazhenski 1915). (C) Kirghiz camp near the head of Bashgumbaz Valley in 1913 (Stein 1933, Plate 379). (D) Center: Crossing debris thrown down by the earthquake near Palaz in the Tanimz Valley in 1915 (Stein 1933, Plate 369). (E) The gorge of Bartang River blocked above Raut by the earthquake. A newly formed tarn can be seen in the foreground; the former riverbed was buried under rock debris in 1915

Seismotectonics of the Pamir

“…Colored beach balls are the same as in Figure a; grey beach balls are from the global CMT moment tensor project [ Dziewonski et al ., ; Ekström et al ., ] for the years between 1976 and 2008. Letters mark events mentioned in text. Green stars mark possible locations of the 1911 M 7.7 Sarez earthquake based on intensity reports (1: Ambraseys and Bilham [], 2 + 3: Bindi et al . [], and the Global Instrumental Earthquake Catalogue‐International Seismological Centre global earthquake catalog 4: Storchak et al .…”

On the Link Between External Forcings and Slope Instabilities in the Piton de la Fournaise Summit Crater, Reunion Island

“…Existing studies on the influence of earthquakes on slope instabilities mainly concern landslides or a mix of RFs and landslide events. They show that earthquakes can produce a permanent decrease in bulk ground strength leading to a slope collapse (Ambraseys & Bilham, ; Marc et al, ). This mechanism can explain why high landslide rates are observed for several months to years after an earthquake (Lin et al, ; Marc et al, ).…”

Reply to “Comment on ‘Total Probability Theorem Versus Shakeability: A Comparison between Two Seismic‐Hazard Approaches Used in Central Asia’ by D. Bindi and S. Parolai” by A. A. Gusev

“…Although we refrain here from touching such a delicate issue that had been discussed in several works (e.g., Albarello and D'Amico, 2008;Beauval et al, 2008;Mucciarelli et al, 2008), we need to note that using observations collected over a short period of time to evaluate the hazard models (e.g., observed maximum intensity) could be misleading (e.g., Iervolino, 2013) and, in particular, lead to an incorrect understanding of the probabilistic seismic-hazard results. Moreover, for future studies, the reliability of the large intensities assigned in central Asia to some historical earthquakes should be re-evaluated, because, considering the adobe, rubble-stone, or masonry houses typical of the area, the MSK (and other scales) saturates at intensity > 7, following the example of the study performed by Ambraseys and Bilham (2012) for the 1911 Sarez earthquake.…”