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Friday, April 22, 2011

Most Dangerous Active Volcanoes on Earth

In the olden days, people thought of them as punishments from the god, but these days, we know it’s actually  tectonic plates shuffling and releasing the red-hot magma from the earth’s core. Volcanoes go about their work silently, showing their presence in full might when they are totally prepared catching the people around unawares.
The recent eruption of Eyjafjallajokull in April 2010 has made the list more interesting than ever, an Icelandic volcano whose name only a few dare to pronounce , made people realize once again how powerful the nature can be and how destructive it might be. Still, it’s nothing compared to the calamities eruptions may cause, wiping out cities and claiming thousands of lives. Classification of the world’s most dangerous volcanoes is subject to debate. Nothing ensures a date in history like a volcano eruption, it happens just when the mother nature flexes her biceps spewing ash and steam miles into the sky. Below are listed some of the most dangerous and vigorous volcanoes due to their explosive history and proximity to large populations.

10. Mauna Loa – Hawaii


Mauna Loa is the largest volcano on Earth in terms of volume and area covered and one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaiʻi in the Pacific Ocean. It is an active shield volcano, with a volume estimated at approximately 18,000 cubic miles, although its peak is about 120 feet (37 m) lower than that of its neighbors.
The volcano has probably been erupting for at least 700,000 years. Mauna Loa’s most recent eruption occurred from March 24, 1984, to April 15, 1984. In view of the hazards it poses to population centers, Mauna Loa is part of the Decade Volcanoes program, which encourages studies of the most dangerous volcanoes.
Mauna Loa is the world’s largest shield volcano in terms of area covered. Mauna Loa is shaped like a shield, because its lava is extremely fluid (it has low viscosity), and therefore although the eruptions are not so explosive, the fluidity speeds up the lava causing more fires and threat to the population.

9. Taal Volcano – Phillipines


Taal Volcano is a complex volcano on the island of Luzon in the Philippines. It consists of an island in Lake Taal, which is situated within a caldera formed by an earlier, very powerful eruption. It is located about 50 km (31 Miles) from the capital, Manila. It is one of the active volcanoes in the Philippines,  all part of the Pacific ring of fire.
The volcano has erupted violently several times, causing loss of life in the populated areas surrounding the lake, the current death toll standing at around 5,000 to 6,000. It was thought to be named as “a volcano inside a volcano” because many believed that the lake that circles the volcano was once a crater or mouth of a volcano.
One of the more devastating eruptions occurred in 1911, which claimed more than a thousand lives. The deposits of that eruption consisted of a yellowish, fairly decomposed tephra with a high sulfur content. The last eruption was in 1977 but it has shown signs of unrest since 1991, with strong seismic activity and ground fracturing events, as well as the formation of small mud pots and mud geysers on parts of the island. Recently, on 8th June’ 2010, the Philippine Institute of Volcanology and Seismology rose its alert level, which indicates the volcano is undergoing magmatic intrusion which could eventually lead to an eruption.

8. Ulawun, Papua New Guinea


A steam plume over the sea from the Ulawun is clearly visible on a satellite image. Ulawun is one of the most active volcanoes in Papua New Guinea and one of its most dangerous. It is the highest volcano in the 1000 km long Bismarck volcanic arc. Ulawun volcano is composed of lava flows interbedded with tephra.
The first recorded eruption of Ulawun was in 1700. Several thousand people live near the volcano.There have been 22 recorded eruptions since the 1700s. The last few years have seen almost constant activity at Ulawun, with frequent small explosions. Eruptions originate from a central crater. Its eruptions devastated the NW flank of Ulawun and modified the summit crater. An eruption in 1980 ejected ash to 60,000 ft and produced pyroclastic flows which swept all flanks of the volcano and devastated an area of 20 sq km. The most serious volcanic hazard at Ulawun volcano is catastrophic structural collapse, producing an eruption which could devastate hundreds of sq km in area.
Ulawun volcano is 400 m higher than most of the volcanoes in the Bismarck which indicates it may be at the limit of structural stability. Seismic activity remained high at Ulawun Volcano in 2008. A magnitude 5.1 earthquake hit 10 km west of Ulawun volcano on 28th May 2009. On 14-15 February 2010 ash emissions from Ulawun volcano reached a height of 3.7 km and drifted 95 km.

7. Mount Nyiragongo – DR Congo


Nyiragongo volcano is one of the most active volcanoes in Africa. It is noted for long active lava lakes which appear in the summit crater. Nyiragongo is one of eight volcanoes in the Virunga Mountains. The volcano is located near the town of Goma in the eastern Democratic Republic of Congo. It is a stratovolcano located inside Virunga National Park. Apparently, nowhere else on the globe does such a steep-sided stratovolcano contain a lake of such fluid lava like Nyiragongo. Nyiragongo’s lava lake has at times been the most voluminous known lava lake in recent history.
Since 1882, it has erupted at least 34 times, including many periods where activity was continuous for years at a time.  The last devastating eruption of Nyiragongo occurred on 17th January 17, 2002, when lava flows down the flank of Nyiragongo covered approximately 40% of the town of Goma, rendering at least 120,000 people homeless, displacing most of Goma’s population of 500,000. This volcano is currently active, with Nyiragongo in an eruption that has been ongoing since May 2002. Nyiragongo’s lava lake remains active to this day.
Since January 2009, recurrent seismic swarms have been detected at Rusayo seismic station. The volcanic earthquakes have come mainly from Nyiragongo volcano, which contains an active lava lake. According to a report by scientists from the volcano observatory in Goma the same signs that preceded the 1977 and 2002 eruptions have been identified. Possibly this means another eruption in near future.

6. Mount Merapi – Indonesia


Mount Merapi (literally Mountain of Fire) is a conical volcano located on the border between Central Java and Yogyakarta, Indonesia. It is the most active volcano in Indonesia and has erupted regularly since 1548. It is very close to the city of Yogyakarta, and thousands of people live on the flanks of the volcano.
Merapi is one of the most active volcanoes in Indonesia and has produced more pyroclastic flows than any other volcano in the world. It has been active for 10,000 years. Most eruptions of Merapi involve a collapse of the lava dome creating pyroclastic flows which travel
6 to 7 km from the summit. Some flows have traveled as far as 13 km from the summit, such as the deposit generated during the 1969 eruption. Velocity of these flows can reach up to 110 km/hour. A slow up flow of magma leads to an extrusion of viscous magma, which accumulate and construct a dome in the crater.
There has been no late eruption. Typically, small eruptions occur every two to three years, and larger ones every 10–15 years or so. Its volcanic devastation is claimed to have led to the collapse of the Hindu Kingdom of Mataram. Since 2006, there is increased seismicity at more regular intervals and a detected bulge in the volcano’s cone indicating that fresh eruptions were imminent. Authorities put the volcano’s neighboring villages on high alert and local residents prepared for a likely evacuation. The eruption in 2006 was followed with quakes of long-period oscillation rendering over 3,00,000 people homeless.

5. Galeras – Colombia


Galeras has been an active volcano for at least a million years. It is located in southern Colombia close to the border with Ecuador. Its summit rises 4,276 metres  above sea level. It has erupted frequently since the Spanish conquest, with its first historical eruption being recorded on December 7, 1580. It is currently the most active volcano in Colombia. The city of Pasto with 450,000 inhabitants is located on the eastern slope of Galeras.
Galeras became active again in 1988 after only a 10 years of dormancy. A Decade Volcano conference in the city of Pasto, in 1993, ended in disaster when several of the scientists present mounted an impromptu expedition on 14 January to the crater of Galeras. An eruption occurred unexpectedly while they were at the summit, which resulted in the deaths of six scientists and three tourists.
The volcano has been erupting almost every year since 2000. It is dangerous because of the frequency of unexpected eruptions and the number of lives it has claimed. Two small eruption occurred in 2000 after seven years of quiet at Galeras volcano. The eruptions were preceded by tornillo earthquakes. A hydrothermal eruption occurred in 2002 which ejected lapilli, ash, and clay. Elevated levels of gas emission were recorded and in November 2004 there was an explosive eruption at Galeras. An eruption with shock waves felt as far away as miles was seen in 2005. Between January and June 2006 a lava dome continued to grow in the crater at Galeras volcano.  In following years, there was a four-fold increase in daily long-period earthquakes and many eruptive explosions were seen. Ash plumes were visible at Galeras volcano that reached a maximum height of 6 km above sea level. Thousands of people were evacuated from the area. And most recently, the volcano erupted on January 3, 2010, forcing the evacuation of 8,000 people. This is the 10th such eruption of the volcano in the past year, and the first of 2010. Ash was ejected to a height of 12 km. Hot lava fell 3.5 km from the volcano and started fires. Colombian authorities also stated that it could remain volatile in the weeks to come.

4. Sakurajima – Japan


Sakurajima is an active composite volcano  and a former island (now connected to the mainland) of the same name in Kyūshū, Japan due to the lava flows of the 1914 eruption which caused the former island to be connected with the Osumi Peninsula in Japan. It is often called the Vesuvius of the east, and has been erupting almost constantly.
The volcanic activity still continues, dropping large amounts of volcanic ash on the surroundings. Earlier eruptions built the white sands highlands in the region. Thousands of small explosions occur each year, throwing ash to heights of up to a few kilometers above the mountain. It is dangerous because of its location in a densely populated area, with the city of Kagoshima’s 700,000 residents just a few kilometers from the volcano.
Sakurajima’s activity became more prominent again in 1955, and the volcano has been erupting almost constantly ever since, with 7,300 eruptions recorded in the last 45 years. In light of the dangers it presents to nearby populations, Sakurajima was designated a Decade Volcano in 1991, identifying it as worthy of particular study as part of the United Nations’ International Decade for Natural Disaster Reduction. The city has even built special shelters where people can take refuge from falling debris. On March 10, 2009, Sakurajima erupted, sending debris up to 2 km away. An eruption had been expected following a series of smaller explosions over the weekend.

3. Popocatépetl – Mexico


Popocatépetl is an active volcano and, at 5,426 m (17,802 ft), the second highest peak in Mexico and lies in the eastern half of the Trans-Mexican volcanic belt, is a natural born killer which could be a serious threat to the capital city (inhabited by fairly 9 million people). The residents of Puebla, a mere 40 km east of the volcano, enjoy the views of the snowy and glacier-clad mountain almost all year long. The name loosely translates to “smoking mountain” and the volcano has had more than 20 known eruptions since 1519.
The latest episode began in December 1994 and there’s been almost continuous volcanic activity ever since. The last major eruption was in the year 2000. Thankfully, scientists were able to warn the Mexican government and had thousands of people evacuated from the area. The eruption in December of that year was the largest documented, most likely in thousands of years.
Mexican culture has accounts of this mountain. They say Iztaccíhuatl was a princess in an Aztec tribe. When she came of age, her father wanted her to marry an Aztec prince; but she wanted to marry Popocatépetl. This made emperor furious but agreed to it on one condition:  Popo’s tribe must help the his troops in a war. He intended on Popo dying in the war. Popo and his tribe joined the Aztecs in war, but they abandoned them at the height of  battle. Miraculously, they were still triumphant. Even so, the emperor told Iztaccíhuatl that Popo had died, and wrote a letter to Popo saying Iztac died of sadness. Popo did not believe, sneaked into the palace to and ran away with her to get married, they lived happily for a few years. Suddenly, Iztac got sick and died. An earthquake occurred. A voice from heavens ordered Popo to bring her body to the peak. He obeyed and then laid down next to her and waited to die. Years later, snow covered them and they became two mountains. The two mountains are named after the lovers to this day.

2. Mount Vesuvius – Italy


Mount Vesuvius is a stratovolcano on the Bay of Naples, Italy, about 9 kilometres east of Naples and a short distance from the shore. It is the only volcano on the European mainland to have erupted within the last hundred years. Mount Vesuvius is best known for its eruption in AD 79 that led to the destruction of the Roman cities of Pompeii and Herculaneum, the ruins of this volcano stand to tell the story.
Vesuvius has erupted many times since, most recently in 1944 and is today regarded as one of the most devastating volcanoes in the world because of the population of 3,000,000 people living nearby and its tendency towards explosive eruptions. It is the most densely populated volcanic region in the world. A two week long eruption of Mt Vesuvius volcano began on 18th March 1944 with a lava flow from the summit crater. Eruptions changed to explosive activity on 21st March with eight lava fountains. The lava fountains increased with time, and the last one on 22nd March was the most intense, reaching heights of 1000 m.
The volcano has an eruption cycle of about 20 years, so we are lucky that it didn’t explode for many years over. Since 1944, seismicity at Mt Vesuvius has been marked by moderate-energy events with a frequency of a few hundred per year.

1. Yellowstone Caldera, United States


It is most dangerous because it is an active super-volcano which means  a volcano capable of producing a volcanic eruption with ejecta greater than 1,000 cubic kilometers which is nearly a thousands of times larger than most historic volcanic eruptions. Super volcanic eruptions typically cover huge areas with lava and volcanic ash sufficient to threaten the extinction of species and can even be one of the causes to bring end to the world because once this volcano erupts, it causes all other volcanoes to erupt causing massive tectonic activity.
One of the largest supervolcanoes in the world lying beneath Yellowstone National Park and scientists say it is still active and even the activity is increasing! Though the Yellowstone system, which spans parts of Wyoming, Montana and Idaho, is active and expected to eventually blow its top, scientists think it will erupt any time soon. Supervolcanoes can sleep for centuries or millenniams before producing incredibly massive eruptions that can drop ash across an entire continent.
Erupting every 6 lac years and it’s already 40 thousand years over, significant activity is mounting beneath the surface, scientists say it can erupt anytime. Back to 640,000 years ago, the area that we know as Yellowstone National Park was the epicenter of a cataclysmic volcanic eruption—an eruption one thousand times larger than Mt. St. Helens. The eruption blasted away mountains, unearthed a vast ocean of lava and spewed hundreds of miles of debris into the atmosphere, burying half of the United States with deadly ash. Largely unknown today, this destructive super volcano is still active, turning the picturesque landscape of Yellowstone into one of the harshest environments on the planet. Due to the volcanic and tectonic nature of the region, the Yellowstone Caldera experiences between 1000 and 2000 measurable earthquakes a year, though most are relatively minor. Brutally cold winters fade into majestic summers, but for the animals that call the park home—including Yellowstone’s great icons: the grey wolf, grizzly bear, buffalo and antelope—this unique and hostile land creates a daily, dramatic battle for survival. Yellowstone captures the essence of this bitter and mercurial environment as it follows the animals that live in the midst of this treasured wilderness.

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