Feasibility of earthquake early warning system
(EWS) for the city of Lima, Peru, was investigated using seismic waveform data
from the newly installed real-time strong motion observation network. We
selected waveform data from 24 earthquakes (ML>3.5, depth<100 km) and estimated
sizes and locations of the events using initial P-wave portions, based on the
conventional approaches. For the estimation of earthquake magnitude, we
determined “τc” parameter
using 3 s time window after the P-wave onset. We found a reasonable correlation
between the estimated and catalogue magnitudes for earthquakes in the vicinity
(hypocentral distance<130 km). The hypocenter locations were determined with
the detected P-wave arrival times. To investigate the accuracy of existing
ground-motion prediction equations (GMPEs) in a real-time scheme, we selected
two GMPEs for subduction zone earthquakes to compare the predicted peak ground
accelerations (PGA) with observed ones. We also confirmed that the size of
blind zones of the EWS is not so large for most earthquakes and it is possible
to give an alert to the city of Lima before S-wave arrivals, if a hypocenter
location was accurately determined.
Keywords: Earthquake Early Warning System, Hypocenter, Peak Ground Acceleration, Blind zone.