Hong Kong (ANTARA News) - A powerful earthquake off the Indonesian island of Sumatra on Wednesday again showed the ferocity of the volatile "Ring of Fire", a massive zone of volcanic instability that encircles the Pacific.
The 7.9-magnitude quake struck around 15 kilometres (9.5 miles) under the seabed off the west coast of Sumatra. Buildings in some coastal towns collapsed, but that it was too early to know if there were casualties, police told AFP.
Most of history's deadliest quakes, tremors and volcanic explosions have occurred along this weak line in the Earth's crust, including the eruptions of Krakatoa near Java and Mount St Helens in the United States, as well as the massive quake that sparked the Indian Ocean tsunami of December 2004.
The Ring of Fire stretches along the western coast of the Americas -- Peru was hit by a deadly quake last month -- and through the island nations of the South Pacific and on through Southeast Asia.
It is an interconnected circle of fault lines -- cracks in the Earth's hardened upper crust -- which are under constant pressure from super-hot molten rock beneath.
Occasionally the fissures give in and explode, creating volcanic eruptions and causing the land on either side of the fault line to shift and buckle violently, triggering earthquakes.
The fault lines are actually the margins of huge plates of rock on which the continents sit. These plates are in constant motion.
According to the US Geological Survey, which studies seismic activity, there have been an average of 19.4 quakes of 7.0-plus strength on the Ring each year.
Indonesia has suffered from three catastrophic earthquakes in the past two years.
The 9.3-magnitude quake on December 26, 2004 unleashed tsunamis that crashed into Indian Ocean shorelines and killed 168,000 in Indonesia's Aceh province alone.
Some 5,800 people were killed and 33,000 others injured in a quake on Java island in May last year. Two months later, another quake on Java killed more than 600.
No comments:
Post a Comment