Wikipedia:


Twice as large in energy is different from twice as large in shaking amplitiude.

Yes, I get it, here is a better page:

http://en.wikipedia.org/wiki/Richter_magnitude_scale

9.0 480 megatons 2.0 EJ MW Lisbon earthquake (Portugal), All Saints Day, 1755
MW 2011 Tōhoku earthquake and tsunami (Japan)
9.15 800 megatons 3.3 EJ Toba eruption 75,000 years ago; among the largest known volcanic events.[22]
9.2 950 megatons 4.0 EJ MW Anchorage earthquake (Alaska, USA), 1964
MW Sumatra-Andaman earthquake and tsunami (Indonesia), 2004
9.5 2.7 gigatons 11 EJ MW Valdivia earthquake (Chile), 1960
10.0 15 gigatons 63 EJ Never recorded
12.55 100 teratons 420 ZJ Yucatán Peninsula impact (creating Chicxulub crater) 65 Ma ago (108 megatons; over 4x1030 ergs = 400 ZJ).[23][24][25][26][27]
32 1.5×1043 tons 6.3×1052 J Approximate magnitude of the starquake on the magnetar SGR 1806-20, registered on December 27, 2004.[28]

Earthquakes over 9.0 are very rare, the Anchorage Alaska earthquake of 1964 being the most recent example. From the above numbers, I would use energy yield in megatons (like a nuke) to determine their definition of 'twice as large' and say that it would be an earthquake approx. of 9.19, which would truly be devastating for our area, likely destroying the cities of Vancouver and Seattle, and generating a tsunami that would roll up Puget sound and drown everything in there, including the remains of Seattle.

Cool about the star, too. That's just Carl Sagan-ish incomprehensible shit...