Ocean Tsunami on 26 December, 2004
9.0 undersea earthquake occurred at 00:58:53 UTC. The earthquake
generated a tsunami that was among the deadliest disasters
in modern history. The tsunami wreaked devastation along the
shores of Indonesia, Sri Lanka, South India, Thailand, Maldives
and other countries where waves of up to 30 metres hit the
areas as far as the coast of East Africa sustained damage and
It is estimated that between 228,000 to 310,000 people died as a result of
the tsunami, and the count is still rising. The true number will never be known.
The epicentre of the quake was just north of Simeulue Island north-west of
Sumatra, Indonesia. It was the strongest recorded earthquake since the 9.5
Great Chilean Earthquake in 1960.
See top ten mega earthquakes at: http://neic.usgs.gov/neis/eqlists/
suggested that the magnitude was underestimated with one study
estimating it at 9.3 on the Richter scale. http://www.newscientist.com/
setting of the region. (USGS)
This megathrust earthquake was felt as far away as Bangladesh, India, Malaysia,
Myanmar, Thailand, Singapore and the Maldives. In northern Indonesia the
shaking was felt for up to several minutes. It is estimated that parts of
a-1200 km faultline slipped about 15 m along the subduction zone where the
India Plate dives under the Burma Plate. The India Plate is part of the great
Indo-Australian Plate, which underlies the Indian Ocean and Bay of Bengal,
and is drifting north-east at an average of 6 cm/year (2 inches/year). The
India Plate meets the Burma Plate (which is considered a portion of the great
Eurasian Plate) at the Sunda Trench. At this point the India Plate subducts
the Burma Plate, which carries the Nicobar Islands, the Andaman Islands and
earthquake induced sudden vertical rise of the seabed by several
metres disrupted massive volumes of water, resulting in a tsunami
that struck the coasts of the Indian Ocean. In some places
the tsunami waves reached as far as 2 kms inland and caused
terrible destruction in their path. Please see a full-length
animation of how the waves traveled at: http://ioc.unesco.org/itsu/images/
upload/animation.gif. The animation will show why some
countries were more affected than others. The 1,200 km faultline
affected by the quake was in a nearly north-south orientation;
therefore, the greatest strength of the tsunami waves was in
an east-west direction. Bangladesh, which lies at the northern
end of the Bay of Bengal, had very few casualties despite being
a low-lying country.
showing travel times of the Indian Ocean tsunami waves
would expect that coasts that have a land mass between them and
the tsunami's location of origin are safe but tsunami waves can
diffract around land masses. For example, the Indian state of
Kerala was hit by the tsunami despite being on the western coast
of India. This is also comparable to the western coast of Sri
Lanka, which suffered substantially from the impact. Further,
distance alone is no guarantee of safety; Somalia was hit harder
than Bangladesh despite being much farther away.
The vice-president of the Tsunami Society, Tad Murty, calculated the total
energy of the tsunami waves to be about five megatons of TNT which is more
than twice the total explosive energy used during all of World War II, and
is still much less than the total energy released during the earthquake itself!
the distance to the epicentre the tsunami waves almost traveled
from fifteen minutes to seven hours (for Somalia) to reach the
coastlines. The northern parts of Sumatra were hit immediately,
whereas, Sri Lanka and the east coast of India were hit between
about 90 and 120 minutes later. The shallow water of the Andaman
Sea caused the tsunami waves to travel slower; and therefore
Thailand was hit relatively late. Despite the close distance to
epicenter, the waves reached Thailand’s coast about 2 hours
after the earthquake.
USGS site to the Indian Ocean earthquake and tsunami http://earthquake.usgs.gov/eqinthenews/2004/usslav/
internet links related with the Indian Ocean tsunami
||The Papua New
Guinea Tsunami on July 17, 1998
||A moderate magnitude
7.1 earthquake with the epicentre in northern New Guinea near the
coast triggered an undersea landslide that caused a locally major
tsunami, which caused more than 2000 fatalities. http://walrus.wr.usgs.gov/tsunami/PNGhome.html
earthquake in Chile on May 22, 1960
This earthquake was the largest ever instrumentally recorded.
The epicenter of the earthquake was 60 meters down below the ocean
floor about 100 miles off the coast of Chile out in the Pacific.
It took 12 hours for the tsunami waves to reach New Zealand, and
20 hours after the earthquake the waves reached Japan.
from Chile, Hawaii, and Japan
The U.S. Geological Survey published an 18-page booklet. It contains lessons
on how to survive a tsunami based on accounts from people who survived the
tsunami generated by the largest earthquake ever measured. It also contains
description of what tsunamis are.
Effects of the 1960 Chilean earthquake tsunami in North America
Tad Murty, R.D. Scott, and C Fournier, 2000. A conference paper presented at
The Fourth International Congress on Earth Sciences, in Santiago, Chile, August
||The Krakatau eruption
in Indonesia on August 26, 1883
||After the explosion
and collapse of the volcano, waves were generated that reached 135
feet and destroyed coastal towns and villages along the Sunda Strait
in both the islands of Java and Sumatra, killing 36, 417 people.