Harmonization check of M w within the central, northern, and northwestern European earthquake catalogue (CENEC)

Abstract

Large data sets covering large areas and time spans, and composed from many different independent sources, raise the question of the obtained degree of harmonization. The present study is an analysis of the harmonization with respect to the moment magnitude M w within the earthquake catalogue for central, northern and northwestern Europe (CENEC). The CENEC earthquake catalogue (Grünthal et al., J Seismol, 2009) contains parameters for over 8,000 events in the time period 1000-2004 with magnitude M w ≥ 3.5. Only about 2% of the data used for CENEC has original M w magnitudes derived directly from digital data. Some of the local catalogues and data files providing data give M w , but calculated by the respective agency from other magnitude measures or intensity. About 60% of the local data give strength measures other than M w and these have to be transformed by us using available formulae or new regressions based on original M w data. Although all events are thus unified to M w magnitude, inhomogeneity in the M w obtained from over 40 local catalogues and data files and 50 special studies is inevitable. Two different approaches have been followed to investigate the compatibility of the different M w sets throughout CENEC. The first harmonization check is performed using M w from moment tensor solutions from SMTS and Pondrelli et al. (2002, 2007). The method to derive the SMTS is described, e.g., by Braunmiller et al. (2002) and Bernardi et al. (2004) and the data are available in greater extent since 1997. One check is made against the M w given in national catalogues and another against the M w derived by applying different empirical relations developed for CENEC. The second harmonization check concerns the vast majority of data in CENEC related to earthquakes prior to 1997 or where no moment tensor based M w exists. In the case, an empirical relation for the M w dependence on epicentral intensity (I 0 ) and focal depth (h) was derived for 41 master events, i.e., earthquakes, located all over central Europe, with high-quality data. To include also the data lacking h, the corresponding depth independent relation for these 41 events was also derived. These equations are compared with the different sets of data from which CENEC has been com-G. Grünthal, D. Stromeyer, R. Wahlström 614 posed and the goodness of fit is demonstrated for each set. The vast majority of the events are very well or reasonably consistent with the respective relation, so that the data can be said to be harmonized with respect to M w , but there are exceptions, which are discussed in detail.

The probabilistic seismic hazard assessment of Germany—version 2016, considering the range of epistemic uncertainties and aleatory variability

“…The catalogue EMEC (Grünthal and Wahlström 2012) represents the southern expansion of CENEC (south of the study area of this paper) and the temporal extension by 2 years up to 2006. The generally high degree of harmonization achieved in CENEC, which holds for the de facto identical data of EMEC as well, is analysed in Grünthal et al (2009c). The specificity and transparency of descriptions in Grünthal et al (2009a), how these catalogues for the study area were created, enable users to produce further temporal extensions as well as those with respect to lower magnitude thresholds where local sources provide such data.…”

“…15 Logic tree (continued) for each seismic source for handling the epistemic uncertainties in the considered models and parameters. The weights of the branches are given in respective ellipses Bull Earthquake Eng magnitude would be M w = 4.3 according to the master event relation in Grünthal et al (2009c) under consideration of minus 1r as safety margin. Therefore, M min = 4.3 is applied in our PSHA.…”

“…A stable parameter determination was only possible as performed in Stromeyer and Grünthal (2009), but not for the parameters of the source term. Therefore, the well constraint magnitude-intensity relation of Grünthal et al (2009c) is used for this part of the IPE. The hazard calculation in terms of intensity was performed by integrating the normal distribution of the IPE from -1r up to ?…”

Induced seismicity related to geothermal projects versus natural tectonic earthquakes and other types of induced seismic events in Central Europe

“…Relations of magnitudes with require the consideration of focal depths . A chi-square regression of with and , derived on the basis of 41 well investigated Central European master events, yields (Grünthal, 2009b) 0.667 0.30 log 0.10 0.31 … 0.37…”

Induced seismicity in geothermal reservoirs: A review of forecasting approaches

“…A PSHA involves three consecutive steps: 1) Compilation of an earthquake catalogue in the area of interest and definition of local seismic source zones, e.g. [24,25]; 2) Specification of suitable ground motion prediction equations that describe best the attenuation relationships of the seismic waves in the study area [26][27][28][29]; 3) The probabilistic calculation itself, including the quantitative assessment of the uncertainties due to all input parameters (i.e. aleatoric uncertainties) and the uncertainties due to the models used (i.e.…”