|
Disaster in 'Ring of Fire'
18/07/2006 13:40 - (SA)
Jakarta - The earthquake that rocked Java and unleashed another deadly tsunami was the latest disaster in the so-called Pacific "Ring of Fire" that has seen a burst of seismic and volcanic activity this year.
Less than two months ago the central Indonesian region was hit by a 6.3-magnitude quake that killed more than 5 800 people and increased activity at Mount Merapi volcano which was already on high alert for a major eruption.
Each new temblor adds to the infamy of the so-called Ring of Fire, the volatile edges of the north Pacific both on land or undersea that are bounded by the east Asian rim and the west coast of the Americas.
Some of the most dramatic natural disasters of recent history have happened within the Ring's arc, which stretches from Chile, north to Alaska and then west to encompass Japan, Southeast Asia and the Pacific islands.
From the nuclear-like explosion of Krakatoa volcano off the coast of Indonesia in 1883 to the Indian Ocean tsunami that killed 220 000 across 11 nations in late 2004, the Ring's awesome power is legend.
Indonesia suffered the heaviest casualties in the 2004 tsunami disaster, which was triggered by a 9.3-magnitude earthquake off Sumatra island.
The 2004 tsunami was followed by an 8.7-level quake just 160 kilometres to the south on March 28 2005, killing more than 600.
Other large scale disasters within the Ring were the eruption of Mount St Helens in the United States in 1980, the freak quake that felled much of San Francisco in 1906 and the one that devastated Kobe, Japan, in 1995.
Pieces of a puzzle
Since the start of the year there has been an increase in seismic activity with dozens of earthquakes in the Ring and the reawakening of Mount Merapi on Java.
The volcano is still on alert for possible eruption although the warning was last week downgraded from code red, the highest.
The fragile fault lines that skirt the zone are the reason for such geological volatility.
The Earth's crust is made up of a series of rocky plates that literally float on the molten rock of the planet's mantle and core, interlocked over the entire globe like the pieces of a puzzle.
These plates are in constant motion, clashing into each other or moving away from each other, creating stresses and pressure build-ups at their margins.
The edges, or fault lines, are weak points in the planet's surface where the crust drops to just a few miles in thickness; at its thickest it is about 20 miles deep.
Many, mostly small eruptions occur, but occasionally huge volcanic explosions, earthquakes or landslides are generated, as pent up energy is released through the weak fissures.
According to the US Geological Survey, since 1900 there have been on average 19.4 quakes of 7.0-plus strength on the Ring each year, but more than 30 have been recorded so far this year.
But there were just 11 in 2005, suggesting that year's burst may just be a natural fluctuation.
- AFP
|
News
