Earth-Shattering Asteroids

65 MILLION YEARS AGO, A 6 MILE WIDE ASTEROID PLUMMETED TO EARTH
LEADING TO THE EXTINCTION OF THE DINOSAURS.  IT KIND OF MAKES
YOU WONDER WHAT A ROCK LIKE THAT BARRELING INTO THE GLOBE
COULD DO TO US.  JACK HILLS IS A GEOPHYSICIST AT LOS ALAMOS
NATIONAL LABS WHO WONDERED THE SAME THING.  USING COMPUTER
SIMULATIONS, HE MODELED WHAT DAMAGE A GIANT ASTEROID COULD
DO.

Hills: "The worst phenomena, causing the most damage, were tsunamis." 

TSUNAMIS ARE THOSE GIANT TIDAL WAVES--USUALLY CAUSED BY
UNDERWATER EARTHQUAKES--THAT WE ASSOCIATE WITH JAPAN AND
SOUTH AMERICA.  NEVER THE US. NO SUCH LUCK WITH AN
ASTEROID-GENERATED TSUNAMI THOUGH.  IF A METEOR HALF THE SIZE
OF THE ONE THAT WIPED OUT THE DINOSAURS LANDED IN THE NORTH
ATLANTIC, IT WOULD GENERATE A WAVE FIVE MILES HIGH THAT WOULD
SWEEP ACROSS THE EAST COAST. 

Hills: "The eastern coast of the us. . . it ain't there anymore.  Maryland, Delaware, so forth
are gone. . . to put it in simple terms the wave goes all the way up to the foothills of the
Appalachian mountains." 

LUCKILY FOR US, THAT KIND OF ASTEROID CAN ONLY BE EXPECTED ONCE
EVERY 10 MILLION YEARS.  SMALLER ASTEROIDS--LIKE A QUARTER OF A
MILE WIDE, WHICH CAN BE EXPECTED EVERY 3-5 THOUSAND YEARS
WOULD DO LESS DAMAGE.

Hills: "You'd expect it to be 30 meters high when it comes ashore, about 100 feet.  
Compare that to the worst earthquake tsunami in recent time in may of 1960 off Chile. . .it
produced a tsunami one to five meters high."  

AND, HEY, A 100 FOOT TSUNAMI, WOULD REALLY ONLY WIPE OUT THE
COASTLINE.  THE REAL SAVING GRACE HERE, IS THAT WE HAVE
SOMETHING THE DINOSAURS DIDN'T HAVE--LABS LIKE LOS ALAMOS THAT
STUDY WHAT TO DO IF WE EVER DO SEE AN EARTHSHATTERING
ASTEROID HEADED OUR WAY.