A magnitude 7.7 EQ at 33 km depth occurred in the Loyalty Islands, 2271 km north of us this morning.
My RS1D RC144 on Banks Peninsula, NZ gave the following record:
The upper plot is the raw data; middle plot shows waves with timescales less than 1 s; and lower plot shows wave with timescales greater than 1 s. The travel times for P and S waves were calculated using https://service.iris.edu/irisws/traveltime/1/. The surface waves were assumed to travel at 3.5 km/s.
There are some interesting features about this event:
- By the time the P waves reached Banks Peninsula, most of the short period waves had dissipated, leaving mainly waves with periods greater than 1 s.
- There were no apparent S waves.
- The Rayleigh and Love surface waves arrived about 120 s later than expected, but persisted for 15 minutes or more.