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2012.11.02 update
[DONET observed the earthquake in western Canada]


A magnitude 7.7 earthquake occurred at near the Queen Charlotte Islands of Canada (52.769N, 31.927W, depth: 17.5km) on Oct. 27 20:04 (local time; Oct. 28 12:04, Japan time). The USGS (U.S. Geological Survey) reported that the earthquake is a type of reverse fault and occurred at the boundary between the North American Plate and the subducted Pacific Plate.

JAMSTEC have installed DONET (Dense Oceanfloor Network System for Earthquakes and Tsunamis) at Kumanonada. This system consists of 20 observatories and each has a seismometer and a pressure sensor. The seismic waves and tsunamis by the earthquake in western Canada have been observed clearly by the DONET observatories. Figures 1 and 2 show the earthquake and tsunami events detected by the pressure sensors.

The seismic waves were observed after Oct. 28 12:00 (Japan time) and the first wave of the tsunami was detected before Oct. 28 22:00. The wave height of the tsunami at the KME20 observatory (depth: 1977m) is assumed to be approximately 7mm. After the first wave, succeeding waves were also observed.


Figure 1: Pressure sensor data (sea tide was eliminated). The seismic waves were observed after Oct. 28 12:00, Japan time (green frame) and the tsunamis were from before Oct. 28 22:00 (aqua frame).


Figure 2: Enlarged figure of the tsunami data in Figure 1. The first wave was observed before 22:00 and succeeding waves were also observed.