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Australian Society of Exploration Geophysicists ABN 71 000 876 040 ISSN 1443-2471 February 2005 Issue No.114 SSumatranumatran earthquakeearthquake affects the whole world ppageage 2 GGeophysicseophysics aatt NNewmontewmont ppageage 2233 TTsunamisunami ssimulationsimulations CCompanyompany PProfilerofile BBEACHEACH PPETROLEUMETROLEUM ppageage 2255 Geeothermalothermal eenergynergy eexpxpllorationoration takestakes offoff inin SA pagepage 3535 CONTENTS ADVERTISERS 2 Editor's Desk Alpha GeoInstruments . 15 4 President's Piece Auslog . 17 Baigent . 38 5 Preview Information Daishsat Pty Ltd . 13 6 Executive Brief ElectroMagnetic Imaging Technology . OBC Encom . IFC 7 Calendar of Events Flagstaff GeoConsultants Pty Ltd . 4 Fugro Geo Instruments . 20 8 Conferences Geoimage Pty Ltd . 5, 10 - Sendai 2004 Geophysical Software Solutions . 13 - Denver 2004 Grant Geophysical Inc. 20 10 People Leading Edge Geophysics . 12 - ASEG Officers Outer-Rim Exploration Services . 15 - New Corporate Members Professional Investment Services . 4 - 1st ASEG FedEx Systems Exploration (NSW) Pty Ltd . 5 UTS Geophysics . 38 13 Branch News Zonge Engineering . 4 14 Web Waves 2004 Corporate Plus Members - Observing Earth from space Velseis Pty Ltd 16 Canberra Observerd 2004 Corporate Members 19 ASEG Research Foundation Beach Petroleum NL BHP Billiton Minerals Exploration 21 Geophysical Anniversaries Chevron Australia Pty Ltd - Southern Cross early geophysical flights Earth Resource Mapping Encom Technology Pty Ltd 25 Company Profile ENI - Beach Petroleum Fugro Airborne Surveys Geosoft Australia Pty Ltd Haines Surveys Pty Ltd 26 Passive Seismic Normandy Exploration Ltd - what, where and why Oil Search Ltd Origin Energy Resources Ltd 29 3D geophysical processing, visualisation Outer-Rim Exploration Services Pty Ltd Petrosys Pty Ltd and interpretation of rice irrigation PGS Australia Pty Ltd impacts Primary Industries & Resources South Australia Professional Investment Services Pty Ltd 33 Geophysics in the Surveys Rio Tinto Exploration Pty Ltd Santos Ltd 37 Industry News Seismic Asia Pacific Pty Ltd Veritas DGC WesternGeco 39 FASTS/AGC WMC Resources Ltd Woodside Energy Ltd 40 Book Review Zonge Engineering & Research Organisation - Rock and fluid transport in reservoirs FEBRUARY 2005 Preview 1 EDITOR'S DESK established. However, the 2004 event was the interface, involving slip directed perpendicular largest earthquake known to have occurred to the trench, and strike-slip faulting, which outside of the Pacific Basin. occurs several hundred kilometres to the east of the trench and involves slip directed The table below shows the top five. parallel to the trench (see USGS website). The December 26 earthquake occurred as the We also know that all these top five earthquakes result of thrust-faulting at the trench. were associated with shallow thrust faulting at subduction zone plate boundaries. The The Tsunami faulted areas extended over thousands of square kilometres for each event. They also The tsunami generated by the earthquake caused significant damaging tsunamis. caused death and destruction all around the Indian Ocean (even in East Africa where Faulting mechanism 137 people were reported killed). One of the Sumatran earthquake key questions is: Given the occurrence of a affects the whole world The complete faulting mechanism for the giant earthquake, what sort of tsunami will it main Boxing Day 2004 earthquake has not generate and where and when will it strike? Apart from wars and global pandemics, like been finally determined. However, it appears the 1918 Spanish flu, the 2004 Boxing Day (see ‘Preliminary Rupture Model by Chen Ji, Fortunately, a modelling package is now earthquake, that took place off the west coast Caltech at http://neic.usgs.gov/neis/bulletin/ available to address these questions (see of northern Sumatra, had a more widespread neic_slav_ff.html) that the rupture, which Figures 2, 3 & 4 and Titov, V.V., and F.I. impact than any other disaster in the last 200 generated the tsunami, had almost a pure Gonzalez (1997): Implementation and testing years. thrust mechanism. The strike of the fault was of the Method of Splitting Tsunami (MOST) ~274° with a dip of ~13° and a slip The death toll to date is over 280,000, direction of ~55°. The epicentre of which more than 200,000 were from was situated at the south-eastern Indonesia, 30,000 from Sri Lanka and 16,000 end of the main fault, which from India. In addition nearly 9000 foreign propagated northwest for up to tourists from 39 countries have been reported 400 km. The total rupture duration as either dead or missing. The tourists came was estimated at ~200s with a from all the six habitable continents. They maximum slip of ~20 m. The were visiting the area from Argentina to aftershock sequence extended over Iceland, from South Korea to South Africa 1300 km along the plate boundary and from Australia to Canada. In Europe, (see Figure 1) and in the first 12 for example, Germany and Sweden each lost hours after the main event ~55 nearly 1000 of their citizens. earthquakes with magnitudes of 5 or greater were located by USGS. Previous natural disasters have killed more The largest had a magnitude people. Chinese floods in 1887, 1931, 1938/9 of 8.8 and seven were larger and 1959 reportedly killed nearly 7 million than 6.0. people, but these events only appeared to have affected China. The phenomena of The cause of the earthquake is globalisation, cheap travel and multi-national due to the interaction of the India interdependence did not really predominate Plate, which moves northeast at a until the end of the 20th century. At present rate of about 6 cm/year relative to the world in which we live is home to the Burma Plate. This results in 6.4 billion people, an increase of about 70 oblique convergence at the Sunda Fig. 1. Aftershock distribution and tectonic setting of the Boxing Day 2004 earthquake. Note the direction of the interaction, between the percent in the last 40 years, and these people Trench. The oblique motion is India and Burma Plates, which does not coincide with the direction of are rapidly spreading to cover more and more partitioned into thrust-faulting, faulting from the earthquake (55°). The diagram was sourced from: of the land area. So it is not surprising that which occurs on the plate- http://earthquake.usgs.gov/eqinthenews/2004/usslav/tect_lg.gif. natural hazards have the potential now to Location Date Magnitude Co-ordinates cause catastrophic global effects. Chile 22 May 1960 9.5 38.24 S, 73.05 W Prince William Sound, 28 Mar 1964 9.2 61.02 N, 147.65 W So what do we know about the earthquake? Alaska Firstly, although it was a giant earthquake, Andreanof Islands, Alaska 9 Mar 1957 9.1 51.56 N, 175.39 W it was only the fifth largest to have occurred since 1900, when the first global Kamchatka 4 Nov 1952 9.0 52.76 N, 160.06 E Off west coast of 26 Dec 2004 9.0 3.30 N, 95.78 E seismographic networks were being Northern Sumatra 2 Preview FEBRUARY 2005 EDITOR'S DESK model NOAA Technical Memorandum ERL PMEL-112, 11; and Cummins, P., 2004, Small threat, but warning sounded for tsunami research: AUSGEO news, Issue 75, September 2004, www.ga.gov.au). These models are clearly only first approximations to what actually happened but they provide excellent material on which to design improved warning systems. The Future The main focus now is to rebuild the tsunami- affected areas as rapidly as possible from the devastation and destruction they experienced. The next step is to investigate what can be done to minimize the damage from future events. As can be seen from Figure 2 the Fig. 2. Travel-times in 30 minute intervals from a modelled source comprising three fault segments. From travel-times to the main populated areas in http://www.pmel.noaa.gov/tsunami/indo20041226/TT.pdf. Notice that there is only a two hour period from the the region are mostly less than two hours. earthquake taking place and the tsunami arriving in India and Sri Lanka. In that time the earthquake has to be located and its size determined to estimate whether Finally, there needs to be more effective And of course the irony of the earthquake or not it might generate a tsunami. And if regional warning systems using the local is that without Plate Tectonics there would the answer is yes, then all those likely to be Emergency Service Agencies. A simple be no crustal recycling, no oceans, very threatened have to be warned. A big ask. phone call to the Maldives, for example, little atmosphere and the continents would could have reduced the death toll there from all be flat and eroded. Plate Tectonics builds The location problem is the easiest to solve. 82 down to zero, but no system was in place, mountains, enriches soils, regulates the planet’s With current technology seismic signals and nobody called. temperature, concentrates gold, petroleum can be transmitted in real time to regional and other resources, and maintains the sea’s centres, where there will be a seismologist on In any case more than a phone call would be chemical balance. Without it there would be duty 24 hours a day every day to determine needed for Thailand, Indonesia, India and Sri no humans on planet Earth to be at risk from the source parameters. Not easy but it can be Lanka. And even if a system is set up within earthquakes, tsunamis and volcanoes. done, and is already in place for parts of the the next six months, what are the chances of globe right now. it working when the return period of these I would like to thank Phil Cummins of earthquakes is over a hundred years? By the Geoscience Australia for assistance in The next task is harder because appropriate time the next giant earthquake occurs at this compiling this contribution.