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Regional relations converting the surface and body wave magnitudes to moment magnitude for Northern Algeria using the general orthogonal regression method

Khemis Asma, Athmani Allaeddine

Acta Geophysica

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2023

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Vol. 71, no. 6

2747--2762

EN

The existence of several magnitude scales in the compiled earthquake catalogs of a specific region has made the development of regional relations connecting magnitude scales a necessity, especially for creating a homogeneous seismic catalog in which all magnitudes should be converted to a preferred magnitude scale. To consistently estimate all magnitude ranges and avoid the saturation problem for large earthquakes, the preference is always given to the moment magnitude Mw scale, wherein the most complete and reliable catalog used worldwide is the Global Centroid Moment Tensor (GCMT). However, to our knowledge, no study has yielded regional (in Algeria) relationships for converting different magnitudes to the moment magnitude (Mw,GCMT). The main reason is typically due to the lack of data pairs of different magnitude scales with Mw (GCMT). To overcome this issue, in this research paper, the moment magnitudes data used for northern Algeria (the area bounded by 32° to 39° N and 3° W to 10° E) have been taken principally from the GCMT catalog and enhanced with the European-Mediterranean Regional Centroid Moment Tensor catalogs RCMT and ZUR-CMT. Regarding this latter, it has been demonstrated in the literature that for the Mediterranean regions, a minor correction should be addressed before merging its data with the GCMT and RCMT catalogs, which are perfectly correlated. To accomplish this task, the magnitude scales tested against Mw are the surface wave magnitude, MS, and the body wave magnitude mb issued from the international seismological sources of ISC and NEIC for the same boundaries. As long as the earthquake magnitudes, in general, are affected by errors of comparable size, the best and most reliable regression method that considers the errors in both dependent and independent variables for linear conversion problems is the General Orthogonal Regression, which is adopted and applied herein to develop the regional relations.

2

Earthquake source parameters estimated from high rate multi GNSS data: a case study of the 2022 M6.9 Menyuan earthquake

Li Xuechuan, Chen Changyun, Liang Hongbao, Li Yu, Zhan Wei

Acta Geophysica

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2023

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Vol. 71, no. 2

625--636

EN

The epicenter, origin time, and magnitude of the earthquake are critical earthquake source parameters, as they can provide data support for earthquake emergency rescue and earthquake risk research, among others. Here, the high-rate displacement time series of 11 Global Navigation Satellite System (GNSS) stations during the 2022 Menyuan M6.9 earthquake were acquired using GPS, GPS/GLONASS, and GPS/GLONASS/Galileo observations using the PRIDE PPP-AR software. Our analysis revealed that the root mean squares (RMS) of displacement derived from GPS/GLONASS/Galileo relative to GPS derived in the north, east, and up components were improved by 23.3, 34.4, and 24.4%, respectively. The epicenter location of the Menyuan earthquake based on GPS/GLONASS/Galileo-derived time series of each station was 101.201°E and 37.791°N, the earthquake origin time was 17:45:23.7 (UTC), and the moment magnitude was 6.62, which were more accurate than the GPS and GPS/GLONASS results. Although there was no significant advantage of calculating the coseismic displacement by multi-day static solution from GPS/GLONASS/Galileo, our results showed that the multi-GNSS combination can improve the stability of time series and reduce noise, and more realistically describe the surface displacement changes during earthquakes; accuracy of earthquake source parameters estimation, can, therefore, be improved with the use of multi-GNSS data.

3

Moment magnitude determination of local seismic events recorded at selected Polish seismic stations

Wiejacz P., Wiszniowski J.

Acta Geophysica

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2006

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Vol. 54, no. 1

15-32

EN

The paper presents the method of local magnitude determination used at Polish seismic stations to report events originating in one of the four regions of induced seismicity in Poland or its immediate vicinity. The method is based on recalculation of the seismic moment into magnitude, whereas the seismic moment is obtained from spectral analysis. The method has been introduced at Polish seismic stations in the late 1990s but as of yet had not been described in full because magnitude discrepancies have been found between the results of the individual stations. The authors have performed statistics of these differences, provide their explanation and calculate station corrections for each station and each event source region. The limitations of the method are also discussed. The method is found to be a good and reliable method of local magnitude determination provided the limitations are observed and station correction applied.

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Determination of the moment magnitude of mining tremos recorded by seismic stations at Ojców and Książ, Poland

Cembrzyńska-Wróbel B., Domański B.

Acta Geophysica Polonica

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1998

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Vol. 46, nr 3

295-305

EN

The Upper Silesian Basin and the Lubin Copper Basin are a source of included seismicity. Stronger seismic events from these regions are recorded by the stations at Książ (KSP) and Ojców (OJC). In the present paper, the moment magnitude for selected series of mining tremors has been determined using spectral analysis of seismograms. The correlation between the values of seismic moment and the logarithm of the maximum amplitude of S-wave ground velocity and the epicentral distance of the event has been studied. The resultant relations can be used fo determining the magnitudes of local minig tremors.