Comparision among different methods for assessing monitoring capability of seismic station in North-South Seismic Belt

In order to explore the differences and causes of the methods for assessing monitoring capability of different seismic networks, this paper chooses the "probability-based magnitude of completeness" (PMC) and "entire-magnitude-range"(EMR) methods which are the relatively frontier in the world, and the "magnitude-maximum distance" method applied routinely in China Seismic Networks to compare minimum magnitude of completeness (marked as M_p, M_cEMR and M_r, respectively, obtained by the above three methods) in the North-South Seismic Belt region during the time span from 1 October 2008 to 17 September 2015. The consistency of data observation quality is also considered, which is not paid enough attention in previous studies, and the selected seismic events are recorded by at least three stations. The results show that the assessing results of the three methods are significant different, and the difference between any two methods can reach to M_L2.0 for some specific positions in the North-South Seismic Belt. The M_p result is significantly lower than the results by the other two methods in the region to the north of 32°N, low M_r value by the magnitude-maximum distance method is only related to the higher density seismic station region. In general the statistical relationship is M_cEMR < M_p < M_r. Furthermore, the detection capability score results reveal that the station operational level and the completeness in earthquake record analyses are the main reasons that the M_p significantly differs from the results calculated by other methods, and data quality constraint criteria such as the amount constraint of recorded stations whether used or not, will cause significantly different results of the EMR method from other methods. Considering practical situation of the seismic network in operation and calculation principles of the three assessment methods, the PMC method is more reasonable and recommended for earthquake monitoring ability assessment work.