Surface rupture of the 1911 Kebin (Chon–Kemin) earthquake, Northern Tien Shan, Kyrgyzstan

Abstract

The 1911 Chon–Kemin (Kebin) earthquake culminated c. 30 years of remarkable earthquakes in the northern Tien Shan (Kyrgyzstan and Kazakhstan). Building on prior mapping of the event, we traced its rupture in the field and measured more than 50 offset landforms. Cumulative fault rupture length is >155–195 km along 13 fault patches comprising six sections. The patches are separated by changes of dip magnitude or dip direction, or by 4–10 km-wide stepovers. One <40 km section overlaps and is parallel to the main north-dipping rupture but is 7 km north and dips opposite (south). Both ends of the rupture are along mountain front thrust faults demonstrating late Quaternary activity. We computed the moment from each fault patch using the surface fault traces, dip inferred from the traces, 20 km seismogenic thickness, rigidity of 3.3×1010 N m−2 and dip slip converted from our observations of the largely reverse sense of motion vertical offsets. The discontinuous patches with c. 3–4 m average slip and peak slip of <14 m yield a seismic moment of 4.6×1020 Nm (Mw 7.78) to 7.4×1020 Nm (Mw 7.91). The majority of moment was released along the inner eastern rupture segments. This geological moment is lower by a factor of 1.5 from that determined from teleseismic data.

Rate of Slip From Multiple Quaternary Dating Methods and Paleoseismic Investigations Along the Talas‐Fergana Fault: Tectonic Implications for the Tien Shan Range

“…This offset value is surprisingly high, but in the range of coseismic slips reported for large earthquakes. The calculated potential magnitudes are thus comparable with historical and paleoearthquakes reported for the Tien Shan range and its surroundings (Abdrakhmatov et al, ; Arrowsmith et al, ; Campbell et al, ).…”

“…These calculated potential magnitudes agree with historical earthquakes reported in central and western Tien Shan. The most recent large earthquake that generated a long surface rupture is the 1911 Chon‐Kemin earthquake with a cumulative fault rupture length of 155–195 km (Arrowsmith et al, ). During this earthquake, 13 fault patches were activated, with 3–4 m of average slip, with peak slip <14 m, corresponding to moment magnitudes M w ranging from 7.8 to 7.9 (Arrowsmith et al, ).…”

“…The most recent large earthquake that generated a long surface rupture is the 1911 Chon‐Kemin earthquake with a cumulative fault rupture length of 155–195 km (Arrowsmith et al, ). During this earthquake, 13 fault patches were activated, with 3–4 m of average slip, with peak slip <14 m, corresponding to moment magnitudes M w ranging from 7.8 to 7.9 (Arrowsmith et al, ). In 1889, the Chilik earthquake ruptured at least 175 km, involving three oblique strike‐slip fault patches separated by step‐overs of several kilometers (Abdrakhmatov et al, ).…”

“…Bishkek, the capital of Kyrgyzstan, was severely damaged by a destructive earthquake in 1885 ( M 6.9), probably related to the reactivation of thrust faults on the northern border of the Kyrgyz Range (Figure ; Landgraf et al, ). In 1911, the Chon‐Kemin event ( M s 8.2; Figure ) activated several fault segments with average slip of ~4 m over more than 180 km of observed surface rupture (Arrowsmith et al, ), while large landslides affected the whole region (Delvaux et al, 1). The M s 7.3 Suusamyr earthquake in 1992 (Figure ) was the most recent earthquake to strike western Kyrgyzstan and this event is reported as a large thrust‐type earthquake (Ghose et al, ).…”

Assessing Earthquake Early Warning Using Sparse Networks in Developing Countries: Case Study of the Kyrgyz Republic

“…In this work, we will demonstrate how combining these approaches can enhance the capacity of an EEWS, even when dealing with a limited number of stations. In particular, we will show how, even with a small number of stations with nearly optimal locations as defined by previous theoretical studies (Stankiewicz et al, 2013) and limited logistical constraints, an alarm with sufficient lead time could be issued for areas that might suffer serious structural damage, for example, in the case of the repetition of strong historical events like the M = 7.8 Kemin 1911 earthquake (Arrowsmith et al, 2017).…”