area of seismic testing and improving seismic reliability of equipment and structures. My former residence in West Los Angeles was damaged by both the 1971 magnitude 6.7 San Fernando earthquake and the 1994 magnitude 6.7 Northridge earthquake, in the latter case losing the chimney and requiring $25,000 in miscellaneous repairs. The cost of the 1994 Northridge earthquake, which caused 57 deaths, has been estimated as between $20 billion and $40 billion. If the Palos Verde tsunami scenario earthquake did occur in the postulated location, earthquake damage inland would be substantial. This cost has not been estimated; it would be in addition to the $7 billion to $40 billion cited above.
The East Coast of the United States is generally considered a low seismic risk area. However, the entire East Coast of North America—from the Florida Keys to Gander, Newfoundland—faces the open Atlantic in a great arc of densely populated shoreline that extends from latitude 25 degrees north to 50 degrees north. Eastward across the Atlantic, a little more than 100 nautical miles west of southern Morocco, lie the Canary Islands, important waypoints for the early Spanish and Portuguese navigators traveling south along the west coast of Africa. The islands—seven major islands and several smaller islets—were formed by ancient volcanoes. Draw a line due west on the Atlantic Ocean from the westernmost island of La Palma, and after traversing some 3,300 nautical miles of open ocean, you strike land at Melbourne, roughly in the center of Florida’s east coast.
La Palma is a pear-shaped island with a large central volcanic caldera called Taburiente. The caldera has a diameter of 5.5 miles and a peak height, known as the Roque de los Muchachois, 7,900 feet above sea level. There is a large canyon, open to the west that leads from the caldera down to the sea. The overall height of the island is 21,320 feet above the ocean floor. The base of the island is made of material called pillow lava that is cut in places by basaltic dykes. Around 1,300 feet above sea level, there is a dividing line between the upper layer of lava and rock. The island last erupted in 1971.
The concern about La Palma centers on its unique geology and activity. It appears that there is a rift zone running from the south end of the island north to the center, along the back edge of the caldera and