An unusual discovery about how
earthquakes triggered tsunami waves in Haiti could mean that similar coastal
cities, including Los Angeles, are at a higher risk from these deadly waves.
Geologists studying the magnitude-7
earthquake that struck Haiti on 12 January say the risk of destructive tsunamis
could be up to 10 per cent higher than had been thought in places with similar
coastal geology such as Kingston, Jamaica, Istanbul, Turkey, and Los Angeles.
Scientists have long known of the
tsunami risk to Southern California. An underwater landslide just offshore,
triggered by an earthquake, could create a tsunami that would slam into
low-lying areas round Los Angeles within just one minute, researchers have
said, adding that a worst-case scenario could cause $42 billion in damage.
Like Haiti’s capital, these cities
all lie near the coast and near an active geologic feature called a strike-slip
fault where two tectonic plates slide past each other like two hands rubbing
Strike-slip fault systems are not
usually associated with tsunamis. Typically, a fault that moves up-and-down
will move the seafloor and produce massive waves; strike-slip fault systems
slide side-to-side when two plates butt heads. The Haiti quake, however,
triggered massive underwater landslides that, along with a small amount of
ground motion, made the waves, said Matt Hornbach, a study team member and a
geophysicist at the University of Texas in Austin.
“As we look through the
history books, people are starting to realize that slides play a bigger
role,” Hornbach said.
Within minutes after the Haiti
earthquake, a series of tsunami waves, some as high as 9 feet crashed into
parts of the shoreline.
“The geology of Kingston,
Jamaica, is nearly identical to Port Au Prince, Haiti,” Hornbach said.
“It’s primed and ready to go and they need to prepare for it. The good
news is, they have a leg up because they’re aware of the problem.”