Local magnitude determination for Turkey from two independent seismic networks and a consistent M4 + catalogue

Rojo Limón，G.1; Ouillon，G.2; Kissling，E.3; Sornette，D.1,4

2023-03-01

10.1093/gji/ggac395

GEOPHYSICAL JOURNAL INTERNATIONAL   Impact Factor & Quartile

0956-540X

1365-246X

Turkish seismicity is routinely recorded by two broad-band seismic networks: the Turkish National Seismic Network (AFAD 'TU' network) and the Bogazici University Kandilli Observatory And Earthquake Research Institute (KOERI 'KO' network). Each of them has over 200 seismic stations distributed across the country. We obtain a new uniform and consistent local magnitude (Ml) scale for Turkey using data from both networks, as well as the M4 + catalogue with Ml values that results from applying said scale to the events that occurred between 2007 and 2016 within the country. We measure the half peak-to-peak amplitude of the vertical component seismograms and estimate the attenuation parameters through an iterative procedure that fits the logarithm of the amplitude as a function of the hypocentral distance, the local magnitude, the station corrections and a constant accounting for possible systematic differences between amplitudes measured on horizontal seismographs and those measured on vertical seismographs. We additionally scale Ml to the moment magnitude measured by an independent source, obtaining a magnitude relationship accounting for attenuation adjustments, as well as differences between maximum horizontal and vertical amplitudes. The estimated Ml formula shows that station corrections from both networks regionally agree, and that non-zero corrections are centred on zero, within-0.48 and 0.46 magnitude units (corresponding to the 2.5 and the 97.5 quantiles). The new M4 + catalogue with consistent Ml values for AFAD and KOERI shows magnitude residuals that cannot be explained by a Gaussian distribution. We also show a very good agreement between our new Ml value and the original Ml values of AFAD and KOERI, with median differences below 0.1 magnitude units.

Earthquake ground motions Earthquake source observations Seismic attenuation

SCI

English

Others

GEOSCIENCES

2-s2.0-85144612270

Scopus

1.Eth Zürich,Entrepreneurial Risks,Department of Management,Technology and Economics,Zürich,8092,Switzerland
2.Lithophyse,Nice,4 rue de l'Ancien Sénat,06300,France
3.Institute of Geophysics,Swiss Federal Institute of Technology,Eth Zurich,Zurich,CH-8092,Switzerland
4.Institute of Risk Analysis,Prediction and Management (Risks-X),Academy for Advanced Interdisciplinary Studies,Southern University of Science and Technology (SUSTech),Shenzhen,518055,China

Rojo Limón，G.,Ouillon，G.,Kissling，E.,et al. Local magnitude determination for Turkey from two independent seismic networks and a consistent M4 + catalogue[J]. GEOPHYSICAL JOURNAL INTERNATIONAL,2023,232(3):1979-2000.

Rojo Limón，G.,Ouillon，G.,Kissling，E.,&Sornette，D..(2023).Local magnitude determination for Turkey from two independent seismic networks and a consistent M4 + catalogue.GEOPHYSICAL JOURNAL INTERNATIONAL,232(3),1979-2000.

Rojo Limón，G.,et al."Local magnitude determination for Turkey from two independent seismic networks and a consistent M4 + catalogue".GEOPHYSICAL JOURNAL INTERNATIONAL 232.3(2023):1979-2000.