Tectonic Summary
The July 17, 2017 M 7.7 earthquake ESE of Nikol’skoye, Russia occurred as the result of transform faulting on or near the plate boundary between the Pacific and North America plates in the Northwest Pacific Ocean. The focal mechanism solution of the earthquake indicates the earthquake occurred either on a right lateral fault oriented NW-SE, or on a left lateral fault striking NE. At the location of the earthquake, the Pacific plate moves towards the NW at a rate of ~73 mm/yr with respect to North America, effectively moving horizontally past the North America plate at this the western extent of the Aleutian trench. Along the arcuate Aleutian Trench, the motion of the Pacific Plate with respect to the North America Plate changes from almost purely convergent near south-central Alaska, to almost purely translational in the western most Aleutians where the Aleutian Trench meets the Kamchatka trench. The location, depth, and focal mechanism solution of the earthquake are consistent with rupture on the main plate boundary, as right lateral faulting.
The Aleutian trench is seismically active, and the region within 250 km of the July 17, 2017 event has experienced 14 M 6.5 and larger earthquakes since 1900. The largest event was a M 7.8 earthquake that occurred December 17, 1929.
WEAK51 PAAQ 180107
TSUAK1
BULLETIN
Public Tsunami Message Number 2
NWS National Tsunami Warning Center Palmer AK
607 PM PDT Mon Jul 17 2017
...THE TSUNAMI ADVISORY IS CANCELLED...
* The Tsunami Advisory is canceled for the coastal areas of
Aleutian Islands
OBSERVATIONS OF TSUNAMI ACTIVITY - UPDATED
TIME OBSERVED MAX
SITE OF MEASUREMENT TSUNAMI HEIGHT
—————————————— ———————— ———————
Shemya Alaska 1712 PDT Jul 17 0.3ft
RECOMMENDED ACTIONS - UPDATED
IMPACTS - UPDATED
* Some areas may continue to see small sea level changes.
* The determination to re-occupy hazard zones must be made
by local officials.