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Study of Recent Tsunamis Sheds Light on Earthquakes Eos, Vol. 75, No. 1, January 4, 1994 resentative Peter Webb, will be held at the than 10 m, and a total of about 1500 people an important calibration to quantify such Byrd Polar Research Center at The Ohio were killed. Field surveys were made for geological studies. State University, March 6-7, 1994, to gauge these tsunamis and reported in Eos [Satake Coastal behavior of tsunamis needs to be the U.S. community's breadth of interest and et al., 1993; Yeh et al., 1993; Hokkaido Tsu­ examined in more detail. For example, the to discuss the submission of proposals for nami Survey Team, 1993]. The survey teams, field survey of the Hokkaido tsunami re­ the June 1, 1994, U.S. Antarctic Program typically consisting of scientists and engi­ vealed that the maximum run-up height was deadline. Persons interested in attending this neers from various fields, documented the 30 m in a small valley on Okushiri Island, workshop or in receiving further information behavior of the tsunamis in detail. Tsunami but 20 m or less a short distance away; the on the Cape Roberts Project should contact survey data are used for various types of re­ run-up height varies significantly with local Peter Webb. search, ranging from coastal behavior of tsu­ topography. Three-dimensional run-up pro- A project prospectus, Antarctic Strati- namis to past and future earthquakes. cecsses are currently being modeled by the­ graphic Drilling, Cape Roberts Project, Work­ Most tsunamis are caused by shallow oretical, numerical, and experimental meth­ shop Report, can be obtained from the rep­ submarine earthquakes. Indeed, all three ods [Liu et al., 1991]; the field data will be resentatives named below. We welcome tsunamis mentioned above were caused by used to test these models. 1-page research statements-of-interest regard­ magnitude 7-8 earthquakes. Fault motion To prepare for the hazards of future tsu­ ing drill core or site investigations. Please causes ocean bottom deformation, which namis, such as the one expected to occur in direct them to the appropriate ISC member generates tsunamis; this tsunami generation the Pacific northwest, we need to integrate and forward a copy to Peter Barrett. The sci­ and propagation can be simulated on com­ studies of paleoseismology, tsunami genera­ ence plan is under review and will be up­ puters. The synthetic tsunamis from seismo- tion, and coastal processes.—Kenji Satake, dated as research statements-of-interest are logically estimated fault parameters usually Department of Geological Sciences, Univer­ received. reproduce the observed tsunami waveforms sity of Michigan, Ann Arbor Cape Roberts Project Representatives [Satake, 1992]. The Nicaraguan earthquake, however, References International Steering Committee: Fred caused much larger tsunamis than are to be Atwater, B. F., and A. L. Moore, A tsunami about Davey, Institute of Geological & Nuclear Sci­ expected from seismological analysis. Sev­ 1000 years ago in Puget Sound, Science, 258, ences Ltd., PO Box 30368, Lower Hutt, New eral similar earthquakes have occurred in 1614, 1992. Zealand; tel. 644473-8208; fax 644471-0977; the world and have been called "tsunami" Bourgeois, J., T. A. Hansen, P. L. Wiberg, and E. G. Kauffman, A tsunami deposit at the Creta­ e-mail [email protected] earthquakes [Kanamori and Kikuchi, 1993], ceous/Tertiary boundary in Texas, Science, 241, Maria Bianca Cita, Sezione Geologia e but why these tsunamis are unusually large 567, 1988. Paleontologia, Dipartimento di Scienze della is not known. Seismic wave analysis of the Hokkaido Tsunami Survey Group, Tsunami devas­ Terra, Universita degli Studi di Milano, Via L. Nicaragua event shows that the fault motion tates Japanese coastal region, Eos Trans. AGU, Mangiagalli 34,1 20133 Milano, Italy; tel. 392- continued for an unusually long time. Fur­ 74, 417, 1993. 2369-8207; fax 392-7063-8361 thermore, comparison of the tsunami field Kanamori, H., and M. Kikuchi, The 1992 Nicaragua Franz Tessensohn, Bundesanstalt fur Ge- earthquake: A slow tsunami earthquake associ­ data with computations from various fault ated with subducted sediments, Nature, 361, owissenschaften und Rohstoffe, Stilleweg 2, models shows that the Nicaragua fault mo­ 714 1993. D-3000 Hannover 51, Germany; tel. 49-511- tion occurred in the top 10 km of oceanic Liu, P! L. -F., C. E. Synolakis, and H. H. Yeh, Re­ 643 2710; fax 49-511-643-2304; e-mail crust, which means the earthquake was port on the International Workshop on Long- ganovex@gatel .bgr.dbp.de much shallower than typical subduction- Wave Run-up, J. Fluid Mech., 229, 675, 1991. Mike Thomson, British Antarctic Survey, Satake, K., Tsunamis, in Encyclopedia of Earth Sys­ zone earthquakes. We now believe that un­ tem Science, edited by W. A. Nierenberg, pp. High Cross, Madingley Road, Cambridge CB3 usually large tsunamis are due to slow fault 389-397, Academic Press, 1992. OET, United Kingdom; tel. 44-223-61188; fax motion within subducted sediments. Satake, K., J. Bourgeois, K. Abe, Y. Tsuji, F. Imam- 44-223-62616; e-mail [email protected] Tsunami waveforms are particularly use­ ura, Y. Iio, H. Katao, E. Noguera, and F. Estrada, bas.ac.uk ful in the study of old earthquakes for which Tsunami field survey of the 1992 Nicaragua earthquake, Eos Trans. AGU, 74, 145, 1993. Peter-Noel Webb, Department of Geologi­ little good-quality seismic data exists; such cal Sciences, Room 130 Orton Hall, The Yeh, H., F. Imamura, C. Synolakis, Y. Tsuji, P. Liu, data have been available only since the and S. Shi, The Flores Island tsunamis, Eos Ohio State University, 155 South Oval Mall, 1960s, whereas tsunami waveforms have Trans. AGU, 74, 369, 1993. Columbus, OH 43210; 1-614-292-7285/8746/ been recorded since the mid-19th century. It 2721; fax 1-614-292-7285/1496/7688; e-mail is important to study old earthquakes be­ pnwebb@magnus. acs. ohio-state. edu cause the typical recurrence time of a large Canopy Research Project Science Coordinator: Peter J. Bar­ subduction-zone earthquake is 100 years. rett, Antarctic Research Centre, Victoria Uni­ Tsunami analysis of the 1957 Aleutian earth­ Network Seeks Input versity of Wellington, PO Box 600, Welling­ quake—which was believed to be the third PAGE 4 ton, New Zealand; tel. 644471-5336; fax 644- largest of the century—showed that it was 495-5186; e-mail [email protected]— actually much smaller. The earthquake has In July 1993, the Canopy Research Net­ Cape Roberts Project International Steering been downgraded to seventh in the rankings. work was established with a 2-year planning Committee grant from the National Science Foundation Geologists use even older tsunami data. to bring together forest canopy researchers, Recently, a tsunami deposit was found that quantitative scientists, and computer special­ Study of Recent provided evidence for an earthquake occur­ ists to establish methods for collecting, stor­ ring in the Seattle area about 1000 years ago ing, analyzing, interpreting, and displaying Tsunamis Sheds Light [Atwater and Moore, 1992]. The recurrence three-dimensional data that relate to tree on Earthquakes of large earthquakes in the Pacific northwest, crowns and forest canopies. along the Cascadia Subduction Zone, has The CRN is now soliciting input from sci­ been estimated from tsunami deposits as PAGE 3 entists in other fields who may have devel­ well as from other paleoseismological data. oped techniques and software to help obtain In the space of one year, three major de­ Abnormal sediments in Texas and Mexico answers to questions that concern the com­ structive tsunamis, or seismic sea waves, have been interpreted to be tsunami depos­ plex three-dimensional structure of tree devastated coastal regions of Nicaragua its, apparently from a gigantic meteorite im­ crowns and forest canopies. Over the next 3 (September 2, 1992), Flores Island, Indone­ pact near Yucatan at the Cretaceous/Tertiary years, the CRN plans to compile an array of sia (December 12, 1992), and Hokkaido, Ja­ boundary [Bourgeois et al., 1988], when a research questions and issues requiring in­ pan (July 12, 1993). The maximum run-up mass extinction took place. Study of depos­ formation on canopy structure, examine use­ heights of each of these tsunamis were more its from recent tsunami events will provide ful information models and software tools This page may be freely copied. .
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