10 Most Devastating Earthquakes of All Time

Posted on March 17, 2010 by Rashid Faridi

Dear Readers

Ashley Merusi sent  me this very good post by email and wished to pass it on.I am reproducing it here.Enjoy

1960 Valdivia earthquake:

The Great Chilean Earthquake on May 22, 1960. It is the most powerful earthquake ever recorded, rated at 9.5 magnitude. It caused tsunamis in Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia, and Alaska. Estimates of the death toll range from 2,231 to 6,000. The monetary cost ranges between 400 to 800 million US dollars, or 2.9 to 5.8 billion in 2010 dollars.

2004 Indian Ocean earthquake:

The 2004 Indian Ocean earthquake had an epicenter off the west coast of Sumatra, Indonesia, and caused devastating tsunamis along the Indian Ocean, including Indonesia, Sri Lanka, India, and Thailand. Its magnitude was between 9.1 and 9.3. It is one of the deadliest natural disasters in recorded history, killing nearly 230,000 people.

1964 Alaska earthquake:

The 1964 Alaska earthquake is known as the Great Alaska Earthquake. It hit south-central Alaska at a magnitude of 9.2. The earthquake lasted nearly 5 minutes, and is the most powerful recorded earthquake in US and North American history. There were 131 deaths directly caused by the earthquake and its resulting tsunamis.

Kamchatka earthquakes:

In 1737 and 1952, two Kamchatka earthquakes occurred around the same location off the Russian Kamchatka Peninsula. The 1737 earthquake is estimated at a magnitude of 8.3, and 1952’s at 9.0. The 1952 earthquake caused a series of tsunamis around the Kamchatka Peninsula, Kuril Islands, and Hawaii. Damages are estimated around $1 million. No human casualties were reported.

1868 Arica Earthquake:

The 1868 Arica Earthquake occurred near Arica, which was part of Peru at the time. The earthquake caused tsunamis in the Pacific Ocean, causing damage to Peru, Hawaii, and New Zealand’s Charham Islands. Arica, Tacna, Ilo, Torata, Mollendo, Iquique, and Arequipa were almost completely destructed, with an estimated 25,000 casualties. The earthquake has an estimGgated magnitude range from 8.5 to 9.0, with about 400 aftershocks recorded.

1700 Cascadia Earthquake:

This earthquake occurred in the Cascadia subduction zone in 1700 with a magnitude between 8.7 and 9.2. It caused a tsunami on the coast of Japan, and is possibly linked to the Bonneville slide. Evidence of this earthquake includes records of the Japanese tsunami not tied to any other Pacific Rim earthquake, and studies of tree rings that show red cedar trees with outermost growth rings formed in 1699. The Cascadia earthquake is believed to have a magnitude of 9.

1833 Sumatra Earthquake:

The 1833 Sumatra earthquake had an estimated magnitude between 8.8 and 9.2, estimated using uplift from coral microatolls. This earthquake caused a large tsunami on the island of Sumatra between Pariaman to Bengkulu, and possibly damage in the Seychelles. Although there are no records of loss of life, they are described as “numerous.”

2010 Chile Earthquake:

The 2010 Chilean earthquake came in at a magnitude of 8.8 for three minutes. Shaking and tremors were felt in much of Chile and South America, including the cities of Talcahuano, Lota, San Antonio, Arauco, Chiguayente, Cañete, and Buenos Aires. Tsunami warnings were issued in 53 countries, and a tsunami was recorded in the sea at Valparaiso, Chile. As of February 28, 2010, 723 deaths were confirmed, with many more reported missing. This earthquake was so powerful, it is estimated that it shortened day lengths by 1.26 microseconds, and altered Earth’s axis rotation by 3 inches.

1906 Ecuador–Colombia Earthquake:

Ecuador’s 1906 earthquake had a magnitude of 8.8 off the coast of Ecuador and Colombia. It generated a strong tsunami that killed between 500 and 1500 people in Hawaii, arriving in Hilo and Honolulu, and Kahului.

1965 Rat Islands, Alaska Earthquake:

This earthquake occurred in one of the Earth’s most active seismic zones. The 1965 earthquake measured 8.7 magnitude. It caused cracks in wood buildings and runways. There was a tsunami 10.7 meters high on Shemya Island. There was a loss of an estimated $10,000 on Amchitka Island, and at least one recorded aftershock.

Source

Posted in Guest Post, seismic activities | 1 Comment

First ‘Modern’ Human Beings Appear in the Iberian Peninsula?

Posted on March 16, 2010 by Rashid Faridi

Research carried out by a group of archaeologists from the Centre for Prehistoric Archaeological Heritage Studies of the Universitat Autònoma de Barcelona (CEPAP_UAB) at the Cova Gran site (Lleida) has contributed to stirring up scientific debate about the appearance of the first “modern” human beings on the Iberian Peninsula and their possible bearing on the extinction of the Neanderthals.The samples obtained at Cova Gran using Carbon 14 dating refer to a period of between 34,000 and 32,000 years in which this biological replacement in the Western Mediterranean can be located in time, although the study regards as relative the use of Carbon 14 for dating materials from the period of transition of the Middle to Upper Palaeolithic period( 40,000 and 30,000).

The results also support the hypothesis that there was neither interaction nor coexistence between the two species.

read here

Posted in BIODIVERSITY | Leave a comment

Russia, India Plan to Make GPS navigation devices jointly

Posted on March 15, 2010 by Rashid Faridi

Russia and India might establish a joint venture to produce navigation equipment for GPS and GLONASS (Global Navigation Satellite System), according to GPS Daily report. GLONASS is the Russian equivalent of the US GPS and is designed for both military and civilian use. Both systems allow users to determine their positions to within a few meters.Russia currently has a total of 22 GLONASS satellites in orbit, but only 16 of them are operational. The system requires 18 operational satellites for continuous navigation services covering the entire territory of Russia and at least 24 satellites to provide navigation services worldwide. The GLONASS navigation satellite system is expected to start operating worldwide by the end of 2010. As soon as global operations are launched, India will be able to use the civilian signal, allowing users to determine their position to within five to 15 meters.

Sources : http://www.gpsdaily.com/

GIS Development

Posted in GPS, Satellites | Leave a comment

Layers of Atmosphere:Ionosphere

Posted on March 14, 2010 by Rashid Faridi

The ionosphere is a name for the layer of the earth’s atmosphere that is ionized by solar  wind. Even though many believe the space around earth is a vacuum, it is not completely empty. The sun’s upper atmosphere (the corona) is very hot and some of its hydrogen and helium are able to escape the sun’s gravity. Because the gas is hot and is in a constant stream of solar energy it becomes a fully ionized plasma. This streaming plasma is the solar wind, and it flows out past the earth affecting the earth’s magnetic field, the magnetosphere and ionosphere(read here about Anatomy of Sun). The Earth receives a lot of energy from the sun in the form of radiation- about 1370 Watts per square meter.The ionosphere is the uppermost part of the atmosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth.

The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth, stretching from a height of about 50 km to more than 1000 km. It owes its existence primarily to ultraviolet radiation from the sun.

The lowest part of the Earth’s atmosphere, the troposphere extends from the surface to about 10 km. Above 10 km is the stratosphere, followed by the mesosphere. In the stratosphere incoming solar radiation creates the ozone layer. At heights of above 80 km (50 miles), in the thermosphere, the atmosphere is so thin that free electrons can exist for short periods of time before they are captured by a nearby positive ion. The number of these free electrons is sufficient to affect radio propagation. This portion of the atmosphere is ionized and contains a plasma which is referred to as the ionosphere. In a plasma, the negative free electrons and the positive ions are attracted to each other by the electromagnetic force, but they are too energetic to stay fixed together in an electrically neutral molecule.

Ionization depends primarily on the Sun and its activity. The amount of ionization in the ionosphere varies greatly with the amount of radiation received from the sun. Thus there is a diurnal (time of day) effect and a seasonal effect. The local winter hemisphere is tipped away from the Sun, thus there is less received solar radiation. The activity of the sun is associated with the sunspot cycle, with more radiation occurring with more sunspots. Radiation received also varies with geographical location (polar, auroral zones, mid-latitudes, and equatorial regions). There are also mechanisms that disturb the ionosphere and decrease the ionization. There are disturbances such as solar flares and the associated release of charged particles into the solar wind which reaches the Earth and interacts with its geomagnetic field.

Sources:

Wikipedia

The Ionosphere Explained

About the Ionosphere

Posted in earth, Environment | 2 Comments