I've seen stories about this threat on either History or Discovery channel. Pretty scary. Mother Nature hiccups and cities are destroyed, landmasses reformed, and tens of thousands of people die. Since the Richter and the Moment Magnitude (Mw) scales are logarithmic, an event of Mw 10 with an approximate yield of 15 gigatons of TNT would likely be a planet-wide disaster. I was just reading that the Chicxulub impact is estimated to have been a Mw 12.33 event, corresponding to 95.2 teratons. BTW, It seems that Luis and Walter Alvarez have been vindicated. I've read that just a year ago a large panel of scientists concluded that the Chicxulub impact was indeed the cause of the K/T extinction. (Cited at Wikipedia, but here's a link to the original article in Science: http://www.sciencemag.org/content/327/5970/1214.abstract.) Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of erikhansen@thebluezone.net Sent: Saturday, March 19, 2011 11:26 AM To: Utah-Astronomy@mailman.xmission.com Subject: [Utah-astronomy] Atlantic Immune to Tsunamis? I recall a story about the Canary Islands El Hierro and La Palma. EL Heirro had a major landslide that created its crescent shape, this landslide was believed to have caused a huge tsunami that reached the east coast of the US with huge waves. La Palma has a similar fault line that bisects the island. One theory is that is if this fault goes, half of the island would fall into the sea causing a Tsunami that would be several hundred meters in height as it hits the eastern US. Seems geologists are somewhat split, some think the Island will spilt in half over a long period of time, some think it will happen in one catastrophic event. The evidence at El Hierro seems to suggest it will happen all at once.