Estimation of dynamic parameters of earthquakes and geodetic moment rate in the south and west of Lut block, East Iran

Document Type : علمی -پژوهشی

Abstract

In South and West Lut block, Dynamic parameters from the earthquakes and geodetic moment rate obtained, during years 2006 to 2015, indicates, in this area seismic and interseismic deformation and risk of seismicity are too much.
In this study, the frequency range of 28 earthquakes with magnitudes MN≥4.5 is studing. By study more than 280 suitable frequency records of earthquakes, dynamic parameters of the earthquakes, for example source dimension, scalar moment, P and S corner frequencies, dynamic parameter of stress drop and moment magnitude, that are important in seismology, are calculated and processed. According to our calculations, moment magnitude (Mw) is between 3.7 to 6.4, seismic moment is between 4.16869E + 14 (Nm) to 5.01187E + 18 (Nm), stress drop is between 13.94 (Bar) to 331.08 (Bar), corner frequency of P, S are 0.33 (HZ) to 3.02 (HZ) and the width of the crust that has been broken is 0.42 (Km) to 5.99 (Km).
In study area, most of stress drop is 331.08. This stress drop is related to Reagan's earthquake that occurred in date 2011.01.27 with Mw = 6.4 on the southern branch of Kahorak fault zone. The stress drop of this earthquake is much higher than the average of 27 other earthquakes (97.9Bar).
Geodetic moment rate in the region is between 6E+16 Nm.yr to 7.75E + 17 Nm.yr.
In the last decade, in parts of area that geodetic moment rate are higher, stress drop is less. In other words, in these areas (areas with slow strain) energy is not free suddenly.It is free slowly.
For study area in recent decades, the rate of seismic moment is 7.42557E + 17 Nm.y and geodetic moment rate is 6.44E + 18 Nm.yr.
In the study area, relationship between moment magnitude (Mw) and seismic moment logarithm (Log (m0)), relationship between seismic moment logarithm with Broken zone (Sr) in the earthquake, relationship between the Broken zone and the slip in the spring of each earthquake (Ss) and relationship between spring of each earthquake and stress drop are respectively Mw=0.600Log(m0)-5.054, Log (m0)=0.643Sr +15.47, Sr=0.013Ss +0.869, Ss=0.673St -31.59.

Keywords

References

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Researches in Earth Sciences
Volume 8, Issue 2 - Serial Number 30
September 2017
Pages 19-34

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