Pacific quake area (Courtesy USGS)
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A string of four earthquakes struck across the central
Pacific today, all within an hour and a half of one another.
The first one, with a magnitude of 7.8, hit at 9:03 AM local
time, (3:03PM PDT) beneath the open ocean 180 miles
north-northwest of Vanuatu. 15 minutes later, a second quake
with a magnitude of 7.7 hit approximately a hundred miles
south-southeast of the first. Then, an hour and ten minutes
after the first quake, a third one hit approximately thirty
miles from the location of the second. On October 8, a 6.8
quake struck near Vanuatu.
These were all first-tier earthquakes. A more moderate
aftershock with a magnitude of 5.1, struck 25 minutes after
the third quake.
It is unusual for three high-intensity earthquakes to strike
in the same area at virtually the same time, and, coming
after last week's major quakes in Samoa and Indonesia,
suggests that there may be a significant subsurface
disturbance taking place beneath the Pacific. Unfortunately,
the ongoing significance of such an event is unknown. There
have also been microquake swarms in northern California and
the Porto Rico trench in recent weeks, but again, the
significance of these events, if any, is unknown.
Today's oceanic quakes caused little or no damage and did
not generate tsunamis.
The California swarm is known as the Olancha Earthquake
Sequence. It began on October 3 and as of October 7 had
reached a total of 435 earthquakes, the strongest of which
took place on October 2, and was of magnitude 5.2. The swarm
is occurring east of Olancha, California near the Death
Valley National Park.
For more information on the Olancha swarm,
click here.
For more information about the Pacific quakes,
click here.
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