Coda Q of 22 local earthquakes recorded on islands located in young and old oceanic lithosphere areas has been measured. We found that the Q values at periods of from 1 to ~2 seconds increase from young to old ocean lithosphere in the same way as for the continent, where the intensity of current tectonic activity shows a strong negative correlation with the coda Q. The Q values increase with frequency proportional to fn, where n was found to be 0.46--0.61, with the higher values for younger oceanic lithosphere, which is again similar to the continents where the active regions have higher n values. |