And again and again the earth trembles
Southeast Asia and the islands of the Pacific do not come to a rest: Heavy earthquakes shook the Republic of Indonesia again, claiming thousands of victims, and the walls shook elsewhere too. In addition, the eruption of the explosive volcano Merapi on Java is still threatening. A series of severe earthquakes shook the Asia-Pacific region over the weekend. More than 5,100 people died in the Indonesian metropolis of Yogyakarta due to an earthquake measuring 6.3 and more than 470 smaller aftershocks. The extent of the material damage to houses, schools, churches, mosques and shops cannot be estimated even three days after the earthquake.
Earthquakes also hit Papua New Guinea, the South Pacific state of Tonga and the Philippines on Sunday. In Tonga, the magnitude of the quake was 6.7 on the Richter scale, in the Philippines it was 5.7. The two tremors in the South Pacific occurred just ten minutes apart on Sunday, but there were no reports of deaths or property damage there. However, experts do not assume that these tremors are connected to the Yogyakarta earthquake.
Two earthquakes of this magnitude in a region in such a short time interval are statistically unusual
Spiro Spiliopoulos With some reluctance, the seismologist Spiro Spiliopoulos from GeoScience Australia called it "statistically somewhat unusual" for two earthquakes of this magnitude to occur in one region within such a short time interval. So far, however, there is no geologically clear evidence that seismic activity can affect one another over several thousand kilometers. The tsunami warning center in Hawaii reported that the earthquake in Tonga took place at a depth of fifty kilometers and that in Papua New Guinea at a depth of 39 kilometers; but neither triggered a tidal wave called a tsunami.
The Pacific region is proving once again these days that it is the most seismologically and volcanically active in the world. In Yogyakarta, for a good six weeks now, people have been watching the Merapi volcano, only thirty kilometers away, whose eruption is only a matter of time, according to the unanimous opinion of volcanologists. However, they qualify that last Saturday's earthquake was not related to the restlessness of Mount Merapi. Rather, it is more associated with the devastating seaquake that caused death and devastation on the coasts of the countries bordering the Indian Ocean on Boxing Day 2004, due to the tsunami it triggered. In the Indonesian city of Aceh, about 2,300 kilometers north of Yogyakarta, 131,000 people died in the tsunami. Even then, experts were warning of further earthquakes in the Indonesian region.
The Merapi volcano, on the other hand, is not the cause of the most recent earthquake."Tectonic earthquakes like that in Yogyakarta are triggered by the collision of the continental plates," said volcanologist Birger Lühr from the GeoForschungsZentrum Potsdam eight days ago in Yogyakarta. Rather, Yogyakarta and Java lie in a so-called subduction zone. Deep underground, off the island's coast, the Indo-Australian tectonic plate and the Eurasian plate are colliding, with the former sliding beneath the latter at about two inches a year. Enormous stresses build up, which are discharged in earthquakes. At the same time, the melting of the lower plate creates magma that rises to the surface and there in turn builds volcanoes like Mount Merapi.
But scientists at the Volcano Research Center in Yogyakarta warn that Mount Merapi's activity may have received an additional boost from the quake. This is also the case on the volcanic Lake Toba after the severe earthquake on the Indonesian island of Nias in the Indian Ocean on March 28.observed in March of last year. The Nias earthquake was also a direct consequence of the Christmas 2004 seaquake.
Merapi volcano is not the cause of the recent quake, because tectonic earthquakes like that of Yogyakarta are triggered by the collision of the tectonic plates
Birger Lühr Indonesia, but also the Philippines, Tonga and Papua New Guinea belong to the Pacific "Ring of Fire", which stretches from Chile up to Alaska and then in the west via Japan, Southeast Asia and the South Seas. The weekend's earthquakes, the threatened eruption of Mount Merapi and the 2004 tsunami are just the most recent evidence of its high level of activity. More than forty percent of all active volcanoes are found in the Pacific Ring of Fire, which, as so-called stratovolcanoes, have the greatest explosiveness, as demonstrated by the eruption of the St. Helens volcano in the USA in 1980 or the lava and mudslides of Pinatubo in the Philippines in 1996.
The eruption of the Indonesian volcano Krakatau in 1883 has also left its mark on mankind. The largest volcanic eruption of modern times reached a value of VEI 6 on the Volcanic Explosivity Index (VEI) from 0 to 8. The energy of the eruption is likely to be between 200 and 2,000 megatons of TNT, which corresponds to about 10,000 to 100,000 Hiroshima bombs, experts estimate. The sounds of the explosion could still be heard in Perth, Australia. The air pressure waves from the detonation were so powerful that they were still measurable after six orbits around the entire earth.
While the dead are being buried in Yogyakarta, doctors and paramedics work tirelessly to treat the more than 10,000 wounded in hospitals and emergency hospitals, aid organizations are transporting medicine, food, water and tents to the region for the 100,000 people who have become homeless and When people start cleaning up, the next catastrophe is already lurking: the eruption of Mount Merapi. No one can predict when exactly it will erupt and how severe its eruption will be. But one thing is certain: Mount Merapi is also one of the highly dangerous stratovolcanoes.
