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Tsunami Laboratory
Institute of Computational Mathematics and Mathematical Geophysics
Siberian Division Russian Academy of Sciences

Novosibirsk,
RUSSIA,
pr. Lavrentieva, 6,
Tel:(383)330-70-70
Fax:(383)330-87-83 Email:gvk@sscc.ru

Expeditions


  • Mozambique Dunes Field Trip
  • Field Trip "Impact Craters in Basalts: Vista Alegre and Vargeao craters"
    AGU 2010 Meetings of the Americas, Foz do Iguasu, Brazil, August 13-14, 2010
  • Chara Expedition June 25 - July 6, 2010
  • Sailing Voyage Southward from the Magellan Strait, November 26 - December 2, 2009
  • Tunguska Conference and Field Trip, June 2008
  • The First Australian Field Trip (November 2005).
  • International Tsunami Expedition in Southern Madagascar, August 29-September 13, 2006.
    The International Tsunami Expedition has finished a two week survey of the southern coast of Madagascar. The research team, consisted of Dr. D.Abbott, Lamont Doherty Earth Observatory of Columbia University, USA, Dr. E.Bryant, University of Wollongong, Australia, Dr. V.Gusiakov, Novosibirsk Tsunami Laboratory, Russia, Dr. W.Masse, Los Alamos National Lab, USA. The team was accompanied by two representatives of the University of Antananarivo, Andriamiranta Raveloson and Hoby Raza. The team obtained field data from large chevrons detected earlier this year using Google Earth imagery. The main purpose of this field trip was to measure the vertical and horizontal extension of the chevrons, to study their genesis and morphological features, and to obtain marine shell in order to determine their age. Another important goal of the expedition was to verify whether or not the chevrons discovered on satellite images represent mega-tsunami deposits and if so, to confirm the inferred run-ups derived from the imagery.

    The expedition, using two rented 4-weel drive vehicles, studied over 150 km of the southernmost Madagascar coast. Participants made several traverses of the four largest chevron formations in this area - near Faux Cape, Cape Saint Marie and along the coast of Fenambosy and Ampalaza Bays. All the chevrons consist of marine sand transported by water, in some cases over the edge of a coastal escarpment over 150 m high. In contrast to wind-blown dunes, which consist of a well sorted, unimodal size distribution, the chevrons are unsorted with a broad range of particle sizes, from small boulders down to clay particles. They also include marine shells. Dump deposits, consisting of a mixture of rock fragments and marine shell, that are typical of mega-tsunami processes were found eastward from Lavanono to Cape Saint Marie. Many of the rock fragments were not locally derived. The team documented maximum runups of 86 m above present day sea level at Ampalaza, 186 m at Fenambosy, 205 m at Faux Cap and 192 m at Cape St Marie. Each of the chevrons represents lateral transport of sediment onto the coast over many kilometers: 20 km at Faux Cap, 30 km at Fenambosy, and 45 km at Ampalaza.

    The measured run-up heights and in land penetration over this extended part of the coast are far beyond the range produced by the largest historically known tectonic tsunamis (seismic and volcanic). Such a great run-up can be produced only by a large-volume submarine landslide somewhere along the nearby continental slope or by an oceanic impact within the Indian Ocean. In the later case, the 29 km Burckle crater found by D.Abbott in 2005 (Abbott et al,2005) at 30S, 61E on a fracture zone of the Southwest Indian Ridge is a good candidate for the source of the mega-tsunami responsible for formation of these chevrons. The Burckle crater is geologically very young, most probably about 4500 to 5000 years old. If C-14 dating of shell collected from the chevrons matches the probable age of the Burckle crater, this will be an important result to prove the reality of the threat of cosmogenic tsunamis in the recent past in the world's oceans.

    The expedition was sponsored by the WAPMERR (World Agency for Planetary Monitoring and Earthquake Risk Reduction), Geneva, Switzerland as a part of their cooperative project with the Novosibirsk Tsunami Laboratory for the development of the World-Wide Tsunami Database and methods for long-term tsunami risk estimation.

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