Early warning
systems in countries depend on how fast they can determine source parameters,
especially magnitude. This study used SeisComP3 (SC3) to determine different
magnitudes for 32 significant earthquakes in the Mediterranean Sea. Different
magnitudes (i.e., mb, Mwp, and mB) under different computational times are
compared with the Mww determined by the United States Geological Survey (USGS)
for evaluation. Tsunami Travel Time (TTT) Software Package by ITIC was used to
calculate the tsunami wave arrival times on Egypt's coasts. The results obtained
for mb confirmed the magnitude saturation, especially for large earthquakes. We
determined the relationship between Mww and Mwp and between Mww and mB. We
obtained Mw estimates from Mwp using the formula implemented in SC3 and those
using the relation of this study. Then, we evaluated the tsunami messages
following the Standard Operational Procedures at different times and compared
those for Mww from USGS. The messages did not change much for the estimates
from SC3 and those from the formula of this study. At 11 minutes after the
origin times, for 28 events, the messages are accurate, and for 4 events, they
are under-estimates for both cases. For mB results at 11 minutes after the
origin times, for 22 events, the messages are accurate, and for 10 events, they
are false when the estimates from SC3 were used. The number of false messages
decreased to 6 when we applied the formula obtained by this study. These
results suggest that Mwp is more stable and accurate than mB. It takes more
than 65 minutes for tsunamis from the Hellenic and Cyprian arcs to reach the
Egyptian coasts. Therefore, tsunami warnings around 11 minutes after the origin
times are expected to be effective for tsunami countermeasures in Egypt.
Keywords:
Tsunami Early Warning
System (TEWS), Magnitude estimation, Mwp, mB, SeisComP3.