User talk:Leelyoko

Welcome!

Hello, Leelyoko, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are a few good links for newcomers:

I hope you enjoy editing here and being a Wikipedian! Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your name and the date. If you need help, check out Wikipedia:Questions, ask me on my talk page, or place {{helpme}} on your talk page and someone will show up shortly to answer your questions. Again, welcome! Robot569 18:55, 21 March 2006 (UTC)[reply]

Tutorial

Ok. If you ever log in, you'll get a link that says you have new messages. Click on the link and there'll be all my messages. So about signing names, see the comment I send you about the other links. So to summarize it: you type four tildes (~~~~), just like it says on the welcome. Remember also that you can ask the Help desk any question about Wikipedia, and they'll answer it later. But if you ask them, check back on the page for your answer.

If you have a question about anything not related to the wiki, ask the Reference Desk. Want to write a song? You can do that too. Also be sure to read the policy and of course obey it. Well have fun being a Wikipedian! Robo bo t 569 01:34, 24 March 2006 (UTC)[reply]

Mount Merapi, Central Java

Hey. I thought you might enjoy reading Mount Merapi, Central Java. Or here it is:

Mount Merapi is a conical volcano in Central Java, Indonesia. It is the most active volcano in Indonesia and has erupted 68 times since 1548. Its name means Mountain of Fire. It is very close to the city of Yogyakarta, and thousands of people live on the flanks of the volcano, with villages as high as 1700 m above sea level. In light of the hazards it poses to populated areas, it has been designated a Decade Volcano.

Geological history

Merapi is the youngest in a group of volcanoes in southern Java. It is situated at a subduction zone, where the Indo-Australian Plate is sliding beneath the Eurasian Plate. It is one of at least 129 active volcanoes in Indonesia, part of the Pacific Ring of Fire - a section of fault lines stretching from the Western Hemisphere through Japan and South East Asia. ^[1]Stratigraphic analysis reveals that eruptions in the Merapi area began about 400,000 years ago, and from then until about 10,000 years ago, eruptions were typically effusive, and the outflowing lava emitted was basaltic. Since then, eruptions have become more explosive, with viscous andesitic lavas often generating lava domes. Dome collapse has often generated pyroclastic flows, and larger explosions, which have resulted in eruption columns, have also generated pyroclastic flows through column collapse.

Typically, small eruptions occur every two to three years, and larger ones every 10-15 years or so. Notable eruptions, often causing many deaths, have occurred in 1006, 1786, 1822, 1872 (the most violent eruption in recent history) and 1930—when thirteen villages were destroyed and 1400 people killed by pyroclastic flows.

A very large eruption in 1006 covered all of central Java with ash. The volcanic devastation is believed to have led to the collapse of the Hindu Kingdom of Mataram, and the ensuing power vacuum allowed Muslims to become the rulers of Java.

Merapi continues to hold particular significance for the Javanese: it is one of four places where officials from the royal palaces of Java's Yogyakarta and Solo make annual offerings to placate the ancient Javanese spirits. ^[2]

1992 eruption

Mount Merapi in August 2003 showing steam venting from the caldera.
*Image courtesy of the Image Science & Analysis Laboratory, NASA Johnson Space Center*

1992 saw an eruption begin at Mount Merapi which continued for the next ten years. During this time, a lava dome was extruded, growing by up to half a metre per day. In 1994, the dome reached the edge of the crater, and from then on, rockfall from the dome produced frequent pyroclastic flows. In late 1994 almost the entire dome collapsed, generating very large pyroclastic flows, which travelled several kilometres from the summit and killed 43 people.

Following the large eruption of November 1994, a new dome formed in the crater, and small explosive eruptions continued for several years, generating scores of lava avalanches and pyroclastic flows every day. Eruptions ended in late 2002.

2006 eruption

In April 2006, increased seismicity at more regular intervals and a detected bulge in the volcano's cone indicated that fresh eruptions were imminent. Authorities put the volcano's neighboring villages on high alert and local residents prepared for a likely evacuation. On 19 April smoke from the crater reached a height of 400 metres, compared to 75 metres the previous day. On 23 April, after nine surface tremors and some 156 multifaced quakes signalled movements of magma, some 600 elderly and infant residents of the slopes were evacuated, their places partly taken by tourists drawn to the area. ^[3]

By early May, active lava flows had begun. On 11 May, with lava flow beginning to be constant, some 17,000 people were ordered to be evacuated from the area ^[4] and on 13 May, Indonesian authorities raised the alert status to the highest level, red, ordering the immediate evacuation of all residents on the mountain. ^[5] Eruptions at the volcano are increasing in intensity, and some reports indicate that large explosions have begun ^[6] ^[7]. Should pyroclastic flows occur, nearby villages will be at very high risk, but many villagers have defied the dangers posed by the volcano and returned to their villages, saying that they needed to tend their live-stock and crops. ^[8]

Monitoring

Merapi is the site of a very active volcano monitoring program. Seismic monitoring began in 1924, and the eruption of 1930 was found to have been preceded by a large earthquake swarm. There is currently a network of 8 seismographs around the mountain, allowing volcanologists to accurately pinpoint the hypocentres of tremors and quakes. A zone in which no quakes originate is found about 1.5 km below the summit, and is thought to be the location of the magma reservoir which feeds the eruptions.

Other measurements taken on the volcano include magnetic measurements and tilt measurements. Small changes in the local magnetic field have been found to coincide with eruptions, and tilt measurements reveal the inflation of the volcano caused when the magma chamber beneath it is filling up.

Lahars (a type of mudflow of pyroclastic material and water) are an important hazard on the mountain, and are caused by rain remobilizing pyroclastic flow deposits. Lahars can be detected seismically, as they cause a high-frequency seismic signal. Observations have found that about 50 mm of rain per hour is the threshold above which lahars are often generated.

References

^ Merapi villagers defy orders to leave homes: The Straits Times
^ Radio New Zealand news report, 23 April 2006
^ Mail & Guardian online, 23 April 2006
^ Lava flows from Indonesia volcano. BBC News, May 4 2006 URL Accessed 2006-05-13
^ Red alert for Indonesia volcano. BBC News, May 13 2006 URL Accessed 2006-05-13
^ Mount Merapi Erupts, ANTARA News, 15 May 2006
^ Indonesia's Merapi volcano spews steam, hot ash, Reuters, 15 May 2006
^ Merapi villages defy orders to leave homes: The Straits Times

Decker, R. and Decker, B. (1997) Volcanoes, 3rd edition, WH Freeman, New York.

External links

be:Мерапі de:Mount Merapi es:Monte Merapi et:Merapi ja:ムラピ山 fr:Mont Merapi id:Gunung Merapi ms:Gunung Merapi nl:Merapi (Java) pl:Merapi zh-min-nan:Merapa Soaⁿ

Hope you like it! tell me about it once you're done reading it! Robot569 18:25, 15 May 2006 (UTC)[reply]

[1] Merapi villagers defy orders to leave homes: The Straits Times

[2] Radio New Zealand news report, 23 April 2006

[3] Mail & Guardian online, 23 April 2006

[4] Lava flows from Indonesia volcano. BBC News, May 4 2006 URL Accessed 2006-05-13

[5] Red alert for Indonesia volcano. BBC News, May 13 2006 URL Accessed 2006-05-13

[6] Mount Merapi Erupts, ANTARA News, 15 May 2006

[7] Indonesia's Merapi volcano spews steam, hot ash, Reuters, 15 May 2006

[8] Merapi villages defy orders to leave homes: The Straits Times

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