A mild (or strong) earthquake was recorded near the Yukon/Alaska
border this morning in the Yakutat region. AEIC gives Ml 5.5, while
PGC says it was Ml 3.1. This was probably a far-field aftershock
from New Zealand as it lies at 102 degrees from that event.
The most unusual earthquakes of the day occurred in Central
Colorado (Ml 2.5) and the Jackson Lake area of
Wyoming (Ml 2.4). Both of these earthquakes also lie
at 102 degrees from the New Zealand mainshock. The edge of the
p- and s- wave shadow zones lies near 102 degrees from the mainshock
and seismic energy is concentrated at this distance. Far-field
triggering effects are thus common along the edge of the shadow zone.
Recall that the Mw 6.1 south of Panama several days ago was also
at 102 degrees from New Zealand.