Elaine Meinel Supkis
After saying the recent big earthquake wasn't part of the Merapi volcano event scientists are now admitting the obvious. Also, it looks increasingly as if this may be a major volcanic event. Volcanic events are like economic bubbles or manias or population explosions: they all have an upper limit which leads to a sudden collapse.
Merapi increases activity, thousands evacuated.
John Roach
for National Geographic News
June 6, 2006
Indonesian officials began evacuating 11,000 people from around the Merapi volcano today, as lava and clouds of gas and debris poured down its steep, upper slopes, news agencies reported.The 9,700-foot (2,900-meter) volcano on the Indonesian island of Java has been sporadically spewing clouds of toxic gas and lava for several weeks.
Experts believe a major eruption could come at any time.
The entire geography of the Sumatran and Javan islands has become destabilized after the huge Boxing Day Earthquake. I said back then, 'In less than two years, there will be a chorus of volcanoes erupting.' Central Java was a spot I picked in particular, it being already pretty active. Merapi, the volcano most active world-wide, was a no-brainer candidate.
Mt. Toba, one of the worst volcanic events in the history of homo sapiens, one that nearly wiped us out, is quite nearby. It seems to have vented its fury and is pretty quiet now and the energy in the lower mantle seems to be finding its outlet further along the island chain.
Just last week, I posted the story about how the subduction zone crust material doesn't dissolve when it is shoved below another tectonic plate but rather, it folds and slithers down through the entire mantle and slogs onto the core. Evidently, this blocks the flow of magma in the mantle which might be why it squeezes upwards like toothpaste out of a tube.
If one draws a diagram of a volcano, it is basically a triangle until it blows up or the magma shifts to one side and forms a new caldera. There is an iron rule in nature: all curves that go upwards have an upper limit and then they go down. Whatever it is, number of gypsy moths eating my forest or number of humans eating the planet, housing bubbles or investment schemes, printing of money or whatever. As things build up in numbers or size, the curve gets steeper and steeper until it destabilizes the entire pyramid and it either blows up or collapses. This is why volcanoes don't rise to infinity. They have an upper limit.
When we were children, we used to make volcanoes in our sand box by burying a hose in an increasingly big sand cone. If we packed the damp sand really well, we could make a big structure but there was always a limit due to the size of the base. When we turned on the hose, the water would erupt and destroy the pretend volcano. This gave us many hours of amusement.
The main thing is, there is no infinity. Once an upper limit is reached, other forces take over and the mountain is often reduced in size quite significantly---and dangerously.
Here are the statistics for Mt. Merapi.
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.
Merapi isn't the tallest volcano. But it is very symetrical. Like several other giants such as the famous Mt. Fuji, for example.
Mt Rainier is a very tall volcano and is also extremely dangerous but less active for now.
Mount Rainier is a stratovolcano in Pierce County, Washington, located 54 miles (87 km) southeast of Seattle, Washington, in the United States. It is the highest peak in the Cascade Range, with a topographical summit of 14,411 feet (4,392 m); there is no greater elevation until the meeting of the borders of Yukon, Alaska, and British Columbia beyond the Alsek River to the north. The mountain and the surrounding area comprise Mount Rainier National Park. The mountain is mostly covered by snow and glaciers, but heat from the volcano keeps areas of the crater rim on its summit cone mostly free of snow and ice. The geothermal heat has also caused the formation of ice caves in the twin summit craters.
Mt. Rainier is 14,410 ft tall. Merapi is only 9,600 ft tall.
The sides of Merapi are steeper than Mt. Rainier and steepness counts.
Merapi is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi volcano beginning during the Pleistocene ended with major edifice collapse perhaps about 2000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequently growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive activity, began SW of the earlier collapse scarp.
This steep instability means a side of the volcano can, when it is convulsing during an eruption, collapse and the energy pent up by the volcano's shape will suddenly explode sideways as we witnessed so vividly with Mt. St. Helens. The volcanist photographing that eruption took spectacular pictures from where he thought he was perfectly safe. He died when the super-heated gases engulfed his outpost.
Click on image to enlarge
Merapi doesn't have glaciers like Mt. Rainier. When the American volcano heats up, it's main danger is the melting of all that ice. Mud flows from it have gone all the way to Tacoma and into the bay there. Many houses, businesses, highways and ports are built on the mud from previous flows. The possibility of a future flow is fairly high but not in the near future, namely, the volcano has been quiet for the last several hundred years which is not very long, geologically speaking. Since Mt. St. Helens has blown up very recently the chances of Mt. Rainier doing likewise is quite probable.
My part of America, upstate NY, hasn't seen volcanoes since about 500 million years ago. Of course, there are no longer any subduction plates here. Everything is very fused together, thank you. It is bad enough battling those gypsy moths. The last thing I need is lava flows or melting glaciers too.
While the whole of the volcano above the sea's surface getting blown off would be destructive, I doubt it will happen that way. Maybe the top third of the mountain may collapse, or something, but it's not clear what will happen. If a Toba type eruption were to happen, the world would be changed quickly.
http://en.wikipedia.org/wiki/Toba_eruption
But Toba is a caldera, similar in ways to Yellowstone. Merapi is a stratovolcano. If Merapi does explode, it will be bad for a while, but I doubt that all of it would explode as the drawing suggests.
Posted by: marty salo | June 07, 2006 at 09:11 PM
While the whole of the volcano above the sea's surface getting blown off would be destructive, I doubt it will happen that way. Maybe the top third of the mountain may collapse, or something, but it's not clear what will happen. If a Toba type eruption were to happen, the world would be changed quickly.
http://en.wikipedia.org/wiki/Toba_eruption
But Toba is a caldera, similar in ways to Yellowstone. Merapi is a stratovolcano. If Merapi does explode, it will be bad for a while, but I doubt that all of it would explode as the drawing suggests.
Posted by: marty salo | June 07, 2006 at 09:12 PM
Blowing off isn't the only thing, collapsing, most often one side collapsing, is more likely.
We still don't know why some volcanoes blow up totally. There is so much to learn about these matters which is why studying volcanoes is a very interesting and growing enterprise.
Not to mention one of the most dangerous. Very, very dangerous!
Posted by: Elaine Meinel Supkis | June 08, 2006 at 08:17 AM
I had been looking for details on the different styles of water and gardening hoses. This posting came up in the results pages. Even though while not exactly precisely what I was searching for, it was well worth the read.
Posted by: Hose Reel | March 01, 2011 at 09:03 PM