RESUMO
Earthquakes are one of the most devastating natural disasters that plague society. Skilled, reliable earthquake forecasting remains the ultimate goal for seismologists. Using the detrended fluctuation analysis (DFA) and conditional probability (CP) methods, we find that memory exists not only in interoccurrence seismic records but also in released energy as well as in the series of the number of events per unit time. Analysis of a standard epidemic-type aftershock sequences (ETAS) earthquake model indicates that the empirically observed earthquake memory can be reproduced only for a narrow range of the model's parameters. This finding therefore provides tight constraints on the model's parameters and can serve as a testbed for existing earthquake forecasting models. Furthermore, we show that by implementing DFA and CP results, the ETAS model can significantly improve the short-term forecasting rate for the real (Italian) earthquake catalog.
RESUMO
Macroseismic data of earthquakes felt in Israel and also recorded instrumentally are analyzed. The analysis yields the following empirical relations: î=0.2 + 1.6M - 2.5log(r)-0.003r, o=0.7, r²=R²+15², M=2.5+0.51, o=1.3, Ie= 1.6M-3.5, o=0.5, M=0.3+2.1 log D, O=0.4, where M is the local magnitude, î is the expected seismic intensity (MSK-scale), R is the epicentral distance Ie is the average seismic intensity in the focal area (within 20 km) and D is the radius of the areain which seismic intensities of grade III or more were observed o is the one standard deviation. Using macroseismic observations in Israel folloding distant-earthquakes and by using the empirical attenuation function (see above). The results indicate a poor correlation between the intensity response of a site and its geological and geotechnical properties (AU)
