New quake, Tsunami warning for Japan

According to the Wikipedia page titled “1700 Cascadia Earthquake,” there have been six major earthquakes off the Pacific Coast since 600 BC that are capable of causing the extreme devastation equivalent to that seen in Japan all the way from Northern California to Northern British Columbia.
Those dates are: 600 BC, 170 BC, 400 AD, 810 AD, 1310 AD, and 1700 AD. From this sequence it is possible to say that the average interval between events is 460 years (five intervals) and it appears possible to construct a linear sequence of 460 year-separated dates beginning at 575 BC with no more than a 55-year error from any real event. It looks like we might expect the next one within 75 years of 2185 AD — No guarantee however!

duncan b: It appears to be dependent on where the report comes from, herewith the description from the USGS site:
Depth
The depth where the earthquake begins to rupture. This depth may be relative to mean sea-level or the average elevation of the seismic stations which provided arrival-time data for the earthquake location. The choice of reference depth is dependent on the method used to locate the earthquake. Sometimes when depth is poorly constrained by available seismic data, the location program will set the depth at a fixed value. For example, 33 km is often used as a default depth for earthquakes determined to be shallow, but whose depth is not satisfactorily determined by the data, whereas default depths of 5 or 10 km are often used in mid-continental areas and on mid-ocean ridges since earthquakes in these areas are usually shallower than 33 km.
I’d always considered it as measured from Average Sea Level.
Kevin – stay safe, and thank you for the updates.

The power of the earth is both awsome and terrifing
The power of man is both limited and laughable

The quake came at 23:32 local time, Thursday 8 April. Even Tokyo was shaken strongly.
Near the epicenter, about 100 people were injured (probably nobody was killed), and 4 million homes underwent electricity shutdown.　The evacuees, still 150 thousand and many are without municipal water supply and sufficient heating, may have been frightened tremendously in darkness.

I was scheduled to give a lecture (on AGW!) to 30 to 50 high-school science teachers on 26 September in Fukushima City, but the contact person emailed me a couple days ago that their facility had been damaged (mechanically, not radioactively) so that my lecture had to be cancelled.
To Kevin: my son, a medical doctor, worked at a hospital in Koriyama City until three years ago. He is now in Utsunomiya, Tochigi Prefecture, which is nearer to the epicenter than Tokyo is.

1125hrs JST
NHK now reporting that 2 people died because of Thursday night’s strong aftershock; a 63 years old woman in Yamagata, and a 79 years old man in Miyagi. I have no details on why those deaths ocurred.

In the light of hindsight; it seems that construction of a nuclear power plant on a tsunami prone ocean shoreline seems to be an incredibly bad idea. Even the east coast of the United States is said to be at risk of a potential 30 to 100 ft. high kinetic impact tsunami that might be generated during a future eruption near Cumbre Vieja on the volcanic ocean island of La Palma, in the Canary Islands if a large unstable portion of the old volcano were to avalanche into the sea.
It is rather ironic that one consideration in development of Japan’s nuclear power policy has been the reduction of CO2 emissions. We can only hope that they will be able to clean up this mess and dump the contamination in sealed containers somewhere like the bottom of Japan Trench where it might eventually be subducted into the asthensophere. I think it is in the vital interest of everyone in the world to contribute to the resolution of this problem.
Canary Island Mega-Tsunami (History Channel)