Stress drop in the sources of intermediate-magnitude earthquakes in northern Tien Shan

Based on the method of polarity of signs of P-waves, the focal mechanisms of 1674 earthquakes with M ≥ 1.6, which occurred on the territory of the Bishkek geodynamic proving ground (BGPG) from 1994 to 2020, were determined. Some characteristics of the complete catalogue are presented. Quantitative distributions by the type of mechanisms and diagrams of azimuths of the main stress axes are constructed. A variety of focal mechanism of earthquake is observed, most of them are reverse fault, oblique reverse fault, and horizontal strike-slip fault. The compression axis for most of the events has a north-northwest direction and a sub-horizontal position. For 183, dynamic parameters (DP, source parameters) were obtained: spectral density Ω0, corner frequency f0, scalar seismic moment M0, source radius (Brune radius) r, and stress drop Δσ. The correlations between DP and energy characteristic (magnitude) and scalar seismic moment are investigated. The smallest correlation coefficient was obtained for stress drop.

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THE STRESS STATE OF THE NORTHERN TIEN SHAN CRUST BASED ON THE KNET SEISMIC NETWORK DATA

Геология и геофизика ◽

10.15372/gig20160303 ◽

2016 ◽

Vol 57 (3) ◽

Keyword(s):

Stress State ◽

Seismic Network ◽

Tien Shan ◽

Network Data ◽

Northern Tien Shan

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High Mountain Asian glacier response to climate revealed by multi-temporal satellite observations since the 1960s

Nature Communications ◽

10.1038/s41467-021-24180-y ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Atanu Bhattacharya ◽

Tobias Bolch ◽

Kriti Mukherjee ◽

Owen King ◽

Brian Menounos ◽

...

Keyword(s):

Mass Loss ◽

River Flow ◽

Tien Shan ◽

High Mountain ◽

Glacier Mass Balance ◽

Temperature And Precipitation ◽

Multi Temporal ◽

The 1960S ◽

Northern Tien Shan

AbstractKnowledge about the long-term response of High Mountain Asian glaciers to climatic variations is paramount because of their important role in sustaining Asian river flow. Here, a satellite-based time series of glacier mass balance for seven climatically different regions across High Mountain Asia since the 1960s shows that glacier mass loss rates have persistently increased at most sites. Regional glacier mass budgets ranged from −0.40 ± 0.07 m w.e.a−1 in Central and Northern Tien Shan to −0.06 ± 0.07 m w.e.a−1 in Eastern Pamir, with considerable temporal and spatial variability. Highest rates of mass loss occurred in Central Himalaya and Northern Tien Shan after 2015 and even in regions where glaciers were previously in balance with climate, such as Eastern Pamir, mass losses prevailed in recent years. An increase in summer temperature explains the long-term trend in mass loss and now appears to drive mass loss even in regions formerly sensitive to both temperature and precipitation.

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