We have conducted hypocenter determinations and calculated local magnitudes for five events, which occurred on November 23, 24, and 29, 2019, May 29, 2020, and October 13, 2022, around Comoro Islands. We retrieved data recorded by the local seismic network and picked P and S arrival times using the seismograms and the probability density functions of their amplitudes. We determined hypocenters using two velocity models, which are a global model and a local model, respectively. The focal depth was set to 10 km considering the difficulty in its determination. The RMS (root-mean-square) residuals for the local model are found to be smaller, which implies that the local model is more appropriate.Then we calculated local magnitudes by amplitude measurements of synthetic Wood-Anderson seismograms. Since duration magnitude is the only one calculated at the Karthala Volcano Observatory of Comoros, the local magnitude will be the second magnitude to be registered in the observatory bulletin. Although the calculated local magnitudes are comparable to the duration magnitudes, their correlation is unclear. Further analyses are necessary to establish their relation.The methods and analyses used in this study are likely to improve earthquake monitoring at the Karthala Volcano Observatory of the Comoros. Further analyses using a larger dataset will be useful for monitoring the seismic and volcanic activities in the study region.
Keywords: Hypocenter, Local magnitude, Comoro Islands