We applied two onsite methods for earthquake early warning, the B-∆ and Pd (peak initial displacement amplitude) methods, to broadband waveform data from the IRIS GNI station in Armenia to investigate their performances. We reviewed the widely used three onsite earthquake early warning methods, which are the B-∆, Tau_c, and Pd methods. Considering the data availability and the characteristics of the methods, we selected the two methods to be applied in this study.
First we calculated B values for 220 events that occurred from 2010 to 2014. The magnitude range is from 3.0 to 7.1 and the epicentral distance range is from 15 to 270 km. We compared our results to the previous studies. Most of the B values are smaller than the expected values from the formulas obtained by previous studies except for larger events (M≥5.0). This result suggests that the B-∆ method may work for larger events.
Second we applied the Pd method to data for the selected 220 events. We integrated velocity data to obtain displacements using a high-pass filter to remove long-period drift following previous studies. We found a good correlation between Pd with PGV (peak ground velocity) and obtained the relation between Pd and PGV by the least squares method. We also found a good correlation between Pd and PGD (peak ground displacement), which is consistent with previous studies.
The results of this study indicate that these onsite methods will work for large earthquakes to estimate epicentral distance, PGV, and PGD using waveform data recorded in Armenia.