Tag Archives: United States Geological Survey

India and Day 26 – Part 3: The Devastating Indian Ocean Tsunami


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Myself By T.V. Antony Raj

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December 26, 2004 – Indian Ocean earthquake and tsunami

On Sunday, December 26, 2004, an undersea megathrust earthquake, known as the Sumatra–Andaman earthquake occurred at 00:58:53 UTC in the Indian Ocean with an epicentre off the west coast of Sumatra, between Simeulue in the Aceh province of Indonesia and mainland Indonesia. The earthquake with a magnitude of Mw 9.1–9.3, is the third largest earthquake ever recorded on a seismograph.

The duration of faulting, between 8.3 and 10 minutes, was the longest ever observed. The behemothic quake caused the entire planet to vibrate as much as 1 centimetre (0.4 inches) and triggered other minor earthquakes as far away as Alaska.

The tsunami was then known by various other names such as: “The 2004 Indian Ocean tsunami,” “South Asian tsunami,” and “Indonesian tsunami.” Since the tsunami occurred on December 26, it was also known as the “Christmas tsunami” and the “Boxing Day tsunami.”

December 26, 2004 Indian Ocean Tsunami (Source: all-that-is-interesting.com)
December 26, 2004 Indian Ocean Tsunami. (Source: all-that-is-interesting.com)

The earthquake triggered a tsunami, considered to be one of the deadliest in history, which inundated coastal communities with waves up to 100 feet (30 meters) high and killed over 230,000 people in fourteen countries. It was one of the deadliest natural disasters in recorded history.

Costlines severely hit by the December 26, 2004 tsunami (Source: academic.evergree.edu)
Coastlines severely hit by the December 26, 2004 tsunami (Source: academic.evergree.edu)

The huge waves racing at the speed of a jet aircraft took fifteen minutes to seven hours to reach the various coastlines. The waves hit the northern regions of the Indonesian island of Sumatra immediately. Thailand was struck about two hours later, despite being closer to the epicentre because the tsunami waves travelled more slowly in the shallow Andaman Sea off its western coast. About an hour and a half to two hours after the quake, Sri Lanka and the east coast of India were hit. The waves then reached the Maldives.

Indonesia was the hardest-hit country, followed by Sri Lanka, India, and Thailand.

The earthquake and resulting tsunami in the Indian Ocean had a devastating effect on India. According to the Ministry of Home Affairs about 18,000 are estimated dead.

The following table compiled by the U.S. Geological Survey shows that a total of 227,898 people died. According to this table, in mainland India and in its territories, the Andaman and Nicobar Islands, 12,405 people died in the tsunami, around 5,640 are missing and 647,599 people have been displaced.

Figures compiled by the U.S. Geological Survey.

Country where
deaths occurred
Confirmed Estimated Injured Missing Displaced
Indonesia 130,736 167,799 n/a 37,063 500,000+
Sri Lanka 35,322 35,322 21,411 n/a 516,150
India 12,405 18,045 n/a 5,640 647,599
Thailand 5,395 8,212 8,457 2,817 7,000
Somalia 78 289 n/a n/a 5,000
Myanmar (Burma) 61 400–600 45 200 3,200
Maldives 82 108 n/a 26 15,000+
Malaysia 68 75 299 6 5,000+
Tanzania 10 13 n/a n/a n/a
Seychelles 3 3 57 n/a 200[70]
Bangladesh 2 2 n/a n/a n/a
South Africa 2 2 n/a n/a n/a
Yemen 2 2 n/a n/a n/a
Kenya 1 1 2 n/a n/a
Madagascar n/a n/a n/a n/a 1,000+
Total ~184,167 ~230,273 ~125,000 ~45,752 ~1.69 million

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The Andaman and Nicobar Islands in the Indian Ocean were devastated by the tsunami, and by the initial quake and several aftershocks that occurred during the following days. The Great Nicobar and Car Nicobar islands were the worst hit among all the islands due to their proximity to the epicentre of the quake and because of the relatively flat terrain.

One-fifth of the population in Nicobar Islands was reported dead, missing or wounded. Chowra Island lost two-thirds of its population of 1,500. Communication was cut off when many islands submerged. The Trinket Island was bifurcated.

Fishing communities were destroyed and very little is known about the effects of the tsunami on the indigenous tribes of the Andaman and Nicobar islands.

The official death toll in the Andaman and Nicobar Islands was 1,310, with about 5,600 missing from the islands. But the unofficial death toll, including those missing and presumed dead, was estimated to be around 7,000.

Map showing Tsunami Affected Area in India.
Map showing Tsunami Affected Areas in India.

The tsunami hit the southeastern regions of the Indian mainland. It inundated villages and devastated cities along the coast. Around 8,000 deaths were reported from Tamilnadu, and around 200 deaths from Kerala. The district of Nagapattinam was the worst hit in Tamil Nadu, with nearly 5,500 deaths.

The tsunami of December 26, 2004 inundated villages and devastated cities along the coast of southeastern regions of the Indian mainland. Crown. (Source: indyas.hpage.co.in)
The tsunami of December 26, 2004 inundated villages and devastated cities along the coast of southeastern regions of the Indian mainland. Crown. (Source: indyas.hpage.co.in)

Surprisingly, Bangladesh, which lies at the northern end of the Bay of Bengal, had only two confirmed deaths, despite being a low-lying country and located relatively near the epicenter. Also, distance alone does not guarantee a safety since Somalia located in the Horn of Africa on the eastern coast was hit harder than Bangladesh even though it is much farther away.

Coasts, with a landmass between them and the location of origin of a tsunami, are usually deemed safe, but tsunami waves can sometimes steer around such landmasses. Being a relatively small island, the western coast of Sri Lanka suffered substantial damages from the impact of the tsunami; likewise, the Indian state of Kerala too was hit by the tsunami, despite being on the western coast of India.

The government of India announced a financial package of about US$200 million to Andaman and Nicobar islands after the tsunami, but the unbearable living conditions due to rise in sea level, constant aftershocks and fear of another similar tsunami, propelled thousands of settlers on the islands to relocate to the Indian mainland.

According to the World Bank, reconstruction was expected to cost more than US$1.2 billion in India alone.

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 Previous ~ India and Day 26 – Part 2: Turmoil in Gujarat

Next → India and Day 26 – Part 4: Terrorist Attacks in Mumbai – 1

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Earthquakes: “Mystery tremors puzzle experts” by Janet Jacobs


Earthquake

By Janet Jacobs Corsicana Daily Sun

December 5, 2012

Corsicana — Reports of earthquake-like tremors starting Tuesday afternoon and continuing until early Wednesday can’t be confirmed as true earthquakes, but experts can’t say what it is, either.

“We started getting calls at 3:09 p.m. (Tuesday),” said Eric Meyers, Navarro County Emergency Coordinator. “The first calls were north of Corsicana in the Hickory Hollow area with two separate residents out there reporting unusual tremors being felt along with a rumbling type of noise.”

After checking with the U.S. Geological Survey website, Meyers also checked with the National Weather Service and state emergency management offices.

“About two hours later, approximately five o’clock, there were additional reports in the same area of heavier tremors, the same vicinity, the same residents,” Meyers said. Another report came from the western part of the county, near Navarro Mills.

After the second round of reports, Meyers posted it on Facebook and suddenly there were more reports, but coming from all over, including Streetman, Purdon, Pursley and Dawson. Some of the reports came from as far away as Freestone and Limestone counties. The line runs about 50 to 60 miles long, and the tremors didn’t act like any other thing except perhaps earthquake booms, which are shallow sometimes undetectable tremors similar to what’s been happening locally.

The range and the description of houses “popping” and shaking didn’t seem to fit anything, including the disturbances reported around fracking drill-sites.

“This is an unexplained event likely of a natural origin,” Meyers said. “We can’t come up with a point of origin or a cause or explanation of why this is happening.”

Still, the National Earthquake Information Center, part of the U.S. Geological Survey, located in Golden, Colo., didn’t see anything on its monitors, according to Don Blakeman, an earthquake analyst at the center.

“We had a call earlier, apparently folks have been feeling something out there for about a day, but we couldn’t find anything, we didn’t see anything on our records,” Blakeman said. “That doesn’t mean something hasn’t happened, but we don’t know what it is.”

If the tremors had been as large as the small quakes that took place around Dallas they would have been detected on their equipment, Blakeman said.

“Little earthquakes don’t automatically trigger the computer’s earthquake location,” he said. “If we have an exact time, though, we can scan the records for it.”

Many tremors aren’t necessarily earthquakes but can have man-made causes, both men said.

“We were trying to determine what was going on, any type of military exercises at a higher level than locally, we worked on this throughout the night and we eliminated everything we could think of and continued to do some through today,” Meyers said.

“We went through the process of elimination on what it could be and ruled out all these different things,” he said. “Whatever it was hasn’t occurred since 4 a.m. Wednesday. It’s unusual, to say the least.”

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Janet Jacobs may be reached via e-mail at jjacobs@corsicanadailysun.com. Want to “sound off” to this article? E-mail: Soundoff@corsicanadailysun.com

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Five States Across the U.S. Reported Trembling Ground and Unexplained Booms (tvaraj.wordpress.com)

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Did Chang Hêng’s Seismoscope (“Earthquake Weathercock”) Ever Exist?


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Myself 

By T. V. Antony Raj

For more than eighteen centuries, people have used devices such as seismoscopes (“Earthquake Weathercock”) to study of earthquakes. The earliest known seismoscope recorded both the occurrence of earthquakes and the azimuth of their origins from the observer.

In the eighteenth century, there were schemes to record the times of earthquakes as well as the dynamics of the ground movement occurring in earthquakes. Significant progress resulted in the late nineteenth century with the development of instruments known as seismographs that produced records of ground motion in earthquakes as a continuous function of time.

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"Houfeng didong y"' - the first Earthquake detector invented by Zheng Heng
“Houfeng didong y”‘ – the first Earthquake detector invented by Zheng Heng

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The Chinese philosopher Chang Hêng, also called Choko and Tyoko, invented the earliest known seismoscope in 132 AD called “Houfeng didong y“. Needham says it resembled a wine jar of diameter six feet. There were eight dragon-heads on the outside surface of the vessel facing the eight principal directions of the compass. Below each dragon-head was a toad, with its mouth opened toward the dragon-head. The mouth of each dragon held an orb. Whenever an earthquake occurred one of the eight dragon-mouths would release an orb into the gaping mouth of the toad below it. The direction of the ground motion determined which of the dragons discharged its orb. Reports say the device detected an earthquake that occurred at a distance of four hundred miles from the site of the seismoscope.

However, to date, nobody knows about the inside of the Chang Hêng’s seismoscope. Seismologists of the nineteenth and twentieth centuries speculated on the mechanism of the Chinese seismoscope. Most believe it must have contained a device similar to a pendulum as the main sensing component to trigger one of the dragons to spew out an orb. In 1886, John Milne, a British geologist and mining engineer who labored on a horizontal seismograph, suggested that the pendulum was a suspended mass – a common pendulum.

In 1939, Akitsune Imamura, a Japanese seismologist, figured that the Chinese seismoscope might have housed an inverted pendulum. Takahiro Hagiwara, Professor Emeritus of the University of Tokyo, constructed an inverted-pendulum seismoscope which worked pretty much like Chang Hêng’s. As per reports the Chinese seismoscope indicated the azimuth of the earthquake. However, Hagiwara’s device responded to transverse movement. It indicated a direction normal to the azimuth between the observer and the epicenter.

In 1959, Needham suggested that Chang Hêng would have calibrated his device empirically for its direction-determining capabilities. He states that knowledge of Chang Hêng’s device existed for more than four hundred years. Works enumerating the functioning of “earthquake weathercocks” appeared as late as the end of the sixth century. Later, however, the seismoscope disappeared from Chinese’s disciplines.

Currently several Chinese writers have questioned whether Chang Hêng’s seismoscope ever existed.

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