A tale of two earthquakes

Two months. Two devastating
earthquakes. One question: Why did the smaller magnitude earthquake kill more
people?

Léogâne, Haiti, a town located 16
miles west of the capital city of Port-au-Prince, was the centre of a
catastrophic 7.0 moment magnitude earthquake that struck on January 12. The
earthquake produced over 50 aftershocks of at least 4.5 measurements. Millions
are affected by this tragedy; hundreds of thousands of residential and
commercial properties have collapsed or remain extremely damaged; and approximately
230,000 people have lost their lives.

Over a month later, an earthquake
struck offshore of Chile from the Maule Region, which is located about 71 miles
north of Concepción, the second largest city of Chile. The earthquake
registered at 8.8 MMS, 1.8 points higher than the Haitian earthquake. The Chile
earthquake was also listed as a level VIII (Destructive) on the Mercalli
intensity scale. It caused over 1,000 casualties.

The February 27 Chilean quake was
500 times more forceful than the one that Haiti experienced in January, yet the
deaths were far less. People are wondering why and a examination of both earthquakes
is needed to explain why this has occurred.

Epicentre
location
The country of Haiti borders the
northern boundary of the Caribbean tectonic plate, which shifts east each year
from the North American plate. Two branches of the strike-slip fault system—the
Septentrional-Orient fault and the Enriquillo-Plaintain Garden fault—are
located in Haiti. A rupture of about 40 miles long in the Enriquillo-Plaintain
fault is believed to have caused the quake, which erupted near the town of
Léogâne, causing major damage to Port-au-Prince, Haiti’s governing centre, and
other nearby towns. The population of Port-au-Prince was roughly three million
before the earthquake, which is nearly half of the entire population of Haiti.

Chile and the rest of the countries
of South America comprise the South American plate, which borders the Caribbean
plate to the north, the Scotia and Antarctic plates to the south, and the Nazca
plate to the west. The Chilean earthquake occurred along the boundary between
the South American and Nazca plates where the two plates converge about three
inches every year. The Nazca plate slid beneath the South American plate
creating a thrust-faulting focal mechanism. The quake began off the coast of
Chile, near the Maule Region, and not on land, generating tremors and tsunamis
that were experienced elsewhere.

Extent
of Damage

The Haiti earthquake wiped out most of Port-au-Prince, damaging infrastructure
including hospitals, transport facilities, and communication systems that were
necessary to respond to the natural disaster. The St. Michel District Hospital,
the largest hospital in southeast Haiti collapsed, as did several Doctors
Without Borders facilities of Port-au-Prince. The control towers at the
Toussaint L’Ouverture International Airport and the Port-au-Prince seaport were
seriously damaged. Losing the seaport control tower made immediate harbour
rescue operations impossible.

The main road between
Port-au-Prince and the city of Jacmel was blocked for ten days by debris, which
also caused problems for rescue attempts. Many government buildings were
damaged or destroyed, including the Palace of Justice, the Presidential Palace,
and the Port-au-Prince Cathedral. The Prison Civile de Port-au-Prince, the main
jail, was also destroying, allowing around 4000 inmates to escape.

Chile’s capital city of Santiago
suffered far less damage than Port-au-Prince. Several buildings in Santiago
received minor damage. Santiago’s International Airport suffered damage,
delaying flights for at least a day. The national Fine Arts Museum was also
terribly damaged and three hospitals collapsed. The earthquake affected other
cities of the Maule Region and at least 500,000 homes have been damaged.

Earthquake Story

The Chilean Marines distribute supplies in Boyeruca, Chile.
Photo: UPI
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