Ya Danny, tlg confirm dengan coral reef ini kan bidang keahlian anda, kontribusi anda sangat kita perlukan. Meskipun Lavigne bukan volcanologist temuannya wajib kita apresiasi. Saya ingat Haroun Tassief yg bukan volcanologist, tapi dokumentasinya banyak di apresiasi oleh para volcanologist dunia.
Selamat berburu koral berumur abat 13. Salam, YSY From: danny.hil...@gmail.com [mailto:danny.hil...@gmail.com] Sent: Saturday, June 16, 2012 10:12 PM To: iagi-net@iagi.or.id Subject: Re: [iagi-net-l] Erupsi besar gunungapi, abad ke 13 di Indonesia ? Di artikel itu disebutkan ada data treering dan historical record di seluruh dunia, jadI wajar saja kalo akurasinya bisa 1-2 tahun. Yang dperdebatkan adalah gunung yang mana? Surprise juga kalo G Rinjani yg meletus kita yang punya gunung ga tahu, malah orang luar yg nemukannya. Padahal seharusnya ada dalam sejarah (masa Majapahit). Bagaimana impact-nya ke masyarakat/kerajaan waktu itu ya? Kalo benar Rinjani, satu fakta nyata kita sangat sedikit mempelajari sejarah dan bencana2 di massa lalu. Saya akan cari juga di data coral rings sekitar tahun itu, sisapa tahu ada sesuatu. Yg jelas data erupsi Tambora 1815 terlihat jelas pada rekaman koral. Frank Lavigne itu rasanya bukan volcanologist. Dia dulu ikut studi tsunami Aceh dan membuat film dan animasi yg bagus. Dia istrinya orang Jogya klo ga salah. Salam DHN Danny Hilman Natawidjaja LabEarth (Laboratory for Earth Hazards) Geoteknologi - LIPI _____ From: Franciscus B Sinartio <fbsinar...@yahoo.com> Date: Sat, 16 Jun 2012 05:42:53 -0700 (PDT) To: iagi-net@iagi.or.id<iagi-net@iagi.or.id> ReplyTo: <iagi-net@iagi.or.id> Subject: Re: [iagi-net-l] Erupsi besar gunungapi, abad ke 13 di Indonesia ? wah hebat ya dating system nya sampai tahu thn nya dengan ketepatan 2 tahun (1257 atau 1258). lah kalau ngak salah katanya saat itu Gunung Toba yang meledak? fbs _____ From: Rovicky Dwi Putrohari <rovi...@gmail.com> To: IAGI <iagi-net@iagi.or.id>; "geologi...@googlegroups.com" <geologi...@googlegroups.com> Sent: Saturday, June 16, 2012 7:31 PM Subject: [iagi-net-l] Erupsi besar gunungapi, abad ke 13 di Indonesia ? Gunung mana ya ? Rdp http://www.sciencenews.org/view/generic/id/341497/title/13th_century_volcano_mystery_may_be_solved 13th Century Volcano Mystery May Be Solved - Science News SELFOSS, Iceland — One of the biggest mysteries in volcanology may finally have a solution. An eruption long thought to have gone off in the year 1258, spreading cooling sulfur particles around the globe, happened the year before in Indonesia, scientists report. Until now, researchers have known a big volcano went off somewhere in the world around that time, but they didn’t know exactly where or when. The new report still remains something of a mystery. Franck Lavigne, a geoscientist at Panthéon-Sorbonne University's Laboratory of Physical Geography in Meudon, France, showed data and close-up photographs of the remains of the perpetrator volcano on June 14 at an American Geophysical Union conference on volcanism and the atmosphere. But he declined to name the specific volcano, saying he had agreed with his international colleagues not to identify it until the work is published in a peer-reviewed journal. “We have new and solid evidence for the biggest volcanic eruption in 7,000 years,” Lavigne said. Consensus in the meeting hallways was that he showed pictures of Indonesia. Lavigne would say only that Indonesia has more than 130 active volcanoes. Scientists know a big eruption must have happened in the mid-13th century because ice cores from Greenland and Antarctica dating to that time contain huge amounts of sulfur. Tree rings, historical records and other evidence also show that the planet cooled soon thereafter. Big volcanic eruptions can spew sulfur particles into the upper atmosphere, where they spread around the globe and reflect sunlight, temporarily chilling the planet. Leading candidates for the 1258 eruption have included Mexico’s El Chichón, which also erupted in 1982, and Quilotoa in the Ecuadorean Andes. But the chemical composition of rocks from those volcanoes, among other factors, don’t really match the 1258 sulfur from ice cores. At the meeting, Lavigne showed geochemical analyses of rocks from his mystery volcano. They matched the chemistry of the polar sulfur almost perfectly. The rocks come from a caldera, the collapsed remains left behind after a large volcanic eruption drains an underground magma chamber. Newly unearthed historical records and other evidence show that climate changes were already happening in the region by the winter of 1257-1258, Lavigne said. “We think the eruption may have been in the late spring or summer of 1257,” he said. That’s nearly a year earlier than previously thought. Computer simulations suggest the eruption sent pumice flying into the air more than 40 kilometers high, showering debris for tens of kilometers around. The eruption would have ranked a 7 on the volcanic explosivity scale that measures an eruption’s magnitude. That scale tops out at 8. Still, volcanologists have spent decades looking for the source of the 1257/1258 eruption. It’s not yet clear whether Lavigne will be able to marshal enough evidence to convince everyone else. -- "Sejarah itu tidak pernah usang untuk terus dipelajari"
