The gravitational resolving power of global seismic networks in the 0.1–10 Hz band

Among the first attempts to detect gravitational waves, the seismic approach pre-dates the digital era. Major advances in computational power, seismic instrumentation and in the knowledge of seismic noise suggest to reappraise its potential. Using the whole earth as a detector, with the thousands of digital seismometers of seismic global networks as a single phased array, more than two decades of continuous seismic noise data are available and can be readily sifted at the only cost of (a pretty gigantic) computation. Using a subset of data, we show that absolute strains h<10^(-17) on burst gravitational pulses and h<10^(-21) on periodic signals may be feasibly resolved in the frequency range 0.1–10 Hz, only marginally covered by current advanced LIGO and future eLISA. However, theoretical predictions for the largest cosmic gravitational emissions at these frequencies are a few orders of magnitude lower.