Pak Rovicky Terimakasih atas pemaparanya, saya terus meningat kejadian gempa pasca aceh nias, yogya, tasik, mentawai, biak-nunfor, selandia baru dan pada akhirnya jepang ( memicu gempa2 minor yang saya rasakan di tembagapura ). Apakah mungkin bahwa dekade ini 2004-Now, menandakan aktifnya zona kegempaan di ujung2 lempeng indoaustralia dan pasifik? mohon pencerahanya.
Amole Mauliate On Thu, Apr 21, 2011 at 5:28 PM, Rovicky Dwi Putrohari <[email protected]>wrote: > Dalam perjalanan panjang umur geologi, naik turunnya aktifitas apa > saja di bumi ini sudah biasa. Ada siklus, ada masa aktif, pasif. > Secara intutif geologist semestinya mudah menerimanya. Sayangnya > rekaman gempa scr detil baru ada sejak 60 tahun lalu. Atau sejak > ditemukan seismometer. > Tantangan memanfaatkan data sekejap utk mengaplikasikan gejala jutaan > tahun lalu. > > Selamat hari bumi 22 april. > > Rdp > ------- > Are we entering an age of major earthquakes? > > A study of more than a century of global seismic records has prompted > some scientists to say that major earthquakes have tended to occur in > clusters. Others disagree. > > By Charles Q. Choi, OurAmazingPlanet Contributor / April 20, 2011 > > A number of devastating quakes have struck across the globe in recent > years --- from Japan to Chile to Haiti --- sparking fears that our > planet is due to experience even more catastrophic temblors in the near > future. > > Three research teams have now combed through 110 years' worth of global > seismic records to see if we might be caught in a global trend of giant > earthquakes. > > Some say we are; others disagree. > > Megaquake clusters > > One pair of researchers found clusters of what they called "megaquakes," > earthquakes of magnitude 9.0 or greater. > > One cluster involved three such quakes between 1952 and 1964, including > the magnitude 9.5 Chile quake of 1960, the largest earthquake ever > recorded on Earth. Another, larger, cluster of magnitude 8.6 and higher > temblors happened between 1950 to 1965, said Charles Bufe and David > Perkins, seismologists with the U.S. Geological Survey in Golden, Colo. > They speculate that the magnitude 8.4 Peru quake in 2001 could mark the > beginning of a new global sequence of major quakes that we are currently > experiencing. > > "This isn't doomsday --- I don't think large earthquakes will occur over > a long period of time --- but we're saying there seems to be a cluster > right now with a higher than normal probability for large quakes," > Bufe told OurAmazingPlanet. "I don't know how long this cluster might > last > --- if we don't get another large earthquake in maybe the next 10 or > 12 years, I would say we're probably out of the cluster." > > Bufe suggested that by sending seismic waves traveling around and > around the planet's surface, very large earthquakes might weaken fault > zones that are already very close to failure. "I think there's a more > than 50 percent chance we'll see another magnitude 9 quake sometime in > the next > decade or so," he said. > > Just chance? > > On the other hand, this apparent recent spike in large quakes could > just reflect random fluctuations in global patterns of seismic > activity. A statistical study from U.S. Geological Survey researcher > Andrew Michael at Menlo Park, Calif., suggests this seeming cluster > pattern disappeared once local aftershocks of the large earthquakes > are taken into account. > > "The most important lesson is that random doesn't mean uniformly > distributed in time --- instead, random processes create apparent > clustering and it is important to carefully consider whether apparent > clusters, or times of less activity, go beyond what is expected from a > simple random process," Michael told OurAmazingPlanet. "So far, my > results show that the apparent clustering is consistent with a random > process." > > If the apparent clustering of these quakes is a matter of chance, then > seismologists can't say whether or not another huge temblor is likely > to > erupt anytime soon. > > "The recent spate of great earthquakes can be explained as a random > fluctuation without predictive power for the future," Michael said. He > added that global predictions of earthquakes and the damage they > inflict should use the longest possible historical record for an area > "rather than focusing on the recent past." > > Long-term record > > Seismologist Richard Aster at the New Mexico Institute of Mining and > Technology and his colleagues looked at historical catalogs of > earthquakes along with more recent findings to create a long-term > record of the cumulative size of earthquakes around the world. > > They suggest there were relatively low rates of big earthquakes during > the periods 1907 to 1950 and 1967 to 2004. However, they found the > rate of large earthquakes increased substantially during the period > 1950 to 1967 and appears to be on the rise again since 2004, since the > devastating magnitude 9.1 to 9.3 earthquake that struck Indonesia and > generated a massive tsunami late that year. > > Still, this finding "is not statistically differentiable from > randomness," Aster told OurAmazingPlanet. > > Progress into understanding whether there are ages of major quakes or > not may be slow "because we just don't get that many great earthquakes > to produce a better sampling of this natural process," Aster said. > > "We only get a few magnitude 9-plus earthquakes per century, for example > --- fortunately for earthquake risks around the world, these events are > rare," Aster said. "There are only 14 earthquakes in the past 111 years > greater than magnitude 8.5." > > Michael agreed. "The main limitation is that we don't have enough data," > he said. "We can't say that clustering doesn't exist. We can only say > that the data doesn't let us reject the hypothesis that the data is > random. If there was more data, then the results could change --- but > that will take decades to occur." > > The scientists detailed their findings on April 14 at the Seismological > Society of America meeting in Memphis, Tenn. > > > http://www.csmonitor.com/Science/2011/0420/Are-we-entering-an-age-of-major-earthquakes > > -- > Sent from my mobile device > > *"Success is a mind set, not just an achievement"* > > > -------------------------------------------------------------------------------- > PP-IAGI 2008-2011: > ketua umum: LAMBOK HUTASOIT, [email protected] > sekjen: MOHAMMAD SYAIFUL, [email protected] > * 2 sekretariat (Jkt & Bdg), 5 departemen, banyak biro... > > -------------------------------------------------------------------------------- > Ayo siapkan diri....!!!!! > Hadirilah Joint Convention Makassar (JCM), HAGI-IAGI, Sulawesi, 26-29 > September 2011 > > ----------------------------------------------------------------------------- > To unsubscribe, send email to: iagi-net-unsubscribe[at]iagi.or.id > To subscribe, send email to: iagi-net-subscribe[at]iagi.or.id > Visit IAGI Website: http://iagi.or.id > Pembayaran iuran anggota ditujukan ke: > Bank Mandiri Cab. Wisma Alia Jakarta > No. Rek: 123 0085005314 > Atas nama: Ikatan Ahli Geologi Indonesia (IAGI) > Bank BCA KCP. Manara Mulia > No. Rekening: 255-1088580 > A/n: Shinta Damayanti > IAGI-net Archive 1: http://www.mail-archive.com/iagi-net%40iagi.or.id/ > IAGI-net Archive 2: http://groups.yahoo.com/group/iagi > --------------------------------------------------------------------- > DISCLAIMER: IAGI disclaims all warranties with regard to information posted > on its mailing lists, whether posted by IAGI or others. In no event shall > IAGI or its members be liable for any, including but not limited to direct > or indirect damages, or damages of any kind whatsoever, resulting from loss > of use, data or profits, arising out of or in connection with the use of any > information posted on IAGI mailing list. > --------------------------------------------------------------------- > >
