Determination of Coda Wave Attenuation Characteristic of the Armutlu Peninsula and Its Surroundings (Middle Marmara Region, Turkey).

Abstract

The Armutlu Peninsula, is located in a geologically complex system on the North Anatolian Fault Zone and inside the high populated Marmara Region. Due to its location and importance, the Marmara Region has been subject to various studies in the past; now, this study is aimed to determine the local attenuation characteristic of the Armutlu Peninsula. In this study, 75 earthquake data that were recorded between 2013-2014, were analyzed by 9 seismic stations. The magnitudes (Ml) and the focal depths of the earthquakes vary from 1.5 to 3.3 and 0.9 to 16.9 km, respectively. A single back-scattering model was used for calculation of the coda wave quality factor. The lapse times were determined between 20 and 40 s at intervals of 5 s and they were filtered at central frequencies of 1.5, 3, 6, 9 and 12 Hz band-pass designed filter. Minimum 5 signal/noise ratio and 0.7 correlation coefficient data used to obtain reliable results. The CODAQ subroutine integrated in the SEISAN software was used for data processing. For each station, low values of the quality factor at 1 Hz (Q o ) and high values of the frequency dependent parameter (n) were determined. In the Armutlu Peninsula and its surroundings, Q c =51f 0.91 for 20 s and Q c =112f 0.72 for 40 s window lengths were calculated by using 9 stations. There is a tendency between increasing Q o and decreasing n parameters. Otherwise, for station TRML, located near the geothermal hotspot, these parameters are in direct proportion with each other, as Q c =46f 0.97 for 20 s and Q c =74f 1.06 for 40 s window lengths. These parameter changes are directly connected with the geothermal activity. the rate of coda wave attenuation [Aki, 1969]. Local/regional recorded coda waves (up to 100 km epicentral distance) and their power spectra as well as coda duration are relatively independent from the focal distance [Aki and Chouet, 1975]. Q c determination studies are generally performed in tectonically active fields, active volcanic regions, earthquake swarm areas, magmatic flows and geothermal areas [

Determination of high-frequency attenuation characteristic of coda waves in the central region of Nepal Himalaya

“…in the coda window. It may be happened due to high intrinsic attenuation (Yavuz and Baris, 2019). The Q c values have been reported significantly lower at thermal springs, volcanic structure, and high magmetic activity Havskov et al, 1989;Canas et al, 1995;Naghavi et al, 2017) than its surrounding areas.…”

“…Relatively less value of coda Q is observed in geothermal activities and hotspot in the different regions of the world (Havskov et al 1989;Canas et al 1995;Naghavi et al 2017). The values of Q c have been reported significantly lower in Turkey due to thermal springs (Yavuz and Baris, 2019), in Washington due to volcanic structure (Havskov et al, 1989) than its surrounding areas. The Q c and n obtained in this study are compatible with the results having a similar tectonic setting of the other active regions of the world, shown in Table 5.…”

“…The Q c values have been reported significantly lower at thermal springs, volcanic structure, and high magmetic activity Havskov et al, 1989;Canas et al, 1995;Naghavi et al, 2017) than its surrounding areas. Yavuz and Baris (2019) reported that both the values of Q c and n increase with an increase in lapse time in the thermal spring area. Intrinsic attenuation is sensitive to physical conditions (geothermal activity) of the underlying medium while scattering attenuation line, shown in Fig.…”

Coda Wave Spatial Variation in Eastern Anatolia, Turkey

“…Low Qc values have consistently been obtained in tectonically active areas [2]. Moreover, some researchers [3][4][5][6][7] show that Qc also reduces in the close proximity of known geothermal reservoirs. This suggests that coda-Q may well be used as an indicator of potential geothermal resources if supplemented with other evidence.…”