Tsunami Physics and Preparedness. March 6, 2005 ICTP Public Information Office 1

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1 Tsunami Physics and Preparedness March 6, 2005 ICTP Public Information Office 1 What we do Provide world-class research facilities for scientists from developing world Foster advanced scientific research, especially in theoretical physics and mathematics Create international forum for exchange of scientific information through comprehensive courses, workshops and seminars March 6, 2005 ICTP Public Information Office 2 1

2 Who benefits 4,000 scientists/year 12 research groups and programmes 40 scientific activities/year Conferences Workshops Schools 100,000 visits since % from developing countries 40% from developed countries 170 nations represented March 6, 2005 ICTP Public Information Office 3 Research and Training for Research Fields of study Applied physics (AP) Condensed matter and statistical physics (CMSP) Earth system physics (ESP) High energy, cosmology and astroparticle physics (HECAP) Mathematics (Math) ICTP-INFN Laboratory (Mlab) March 6, 2005 ICTP Public Information Office 4 2

3 Impact Beyond Trieste Associates Programme since associates in 106 countries Many ICTP Associate Members have achieved distinguished careers in their home countries as members of parliament,ministers, and university chancellors March 6, 2005 ICTP Public Information Office 5 Impact Beyond Trieste OEA Centres and Networks since Networks Africa 9 Asia 8 Europe 1 Latin America Centres Africa 13 Asia 11 Europe 1 Indonesia 1 Latin America 8 Projects Africa 10 Asia 3 Europe 1 Latin America 3 March 6, 2005 ICTP Public Information Office 6 3

4 Abdus Salam,Founding Director Tsunami Physics and Preparadness Trieste, 24th of March

5 26 December 2004 Timeline 00:59 (GMT) Earthquake occurs 01:07 Seismic signals in Australia trigger local alarm 01:10 Pacific Tsunami Warning Center (PTWC) issues message to other observatories based on M8.0 01:14 PTWC issues warning of no threat in Pacific 02:04 PTWC issues 2nd warning, based on M8.5, of possible tsunami in Indian ocean 02:30 PTWC attempts to contact Australian Met Service, does reach Australian Emerg. Management 03:30 Internet reports of casualties in Sri Lanka 05:25 Harvard CMT estimates M8.9 Challenges in Determining Magnitude: Epicenter can be determined rapidly Determining magnitude for very large events is more problematic For great earthquakes (>8.0), several hours of data needed for accurate surface wave magnitude Rapid determination of magnitude could have enabled much earlier warning Geodetic data can help 5

6 How can GPS help? For M6+ events, GPS can determine location, orientation, extent of rupture, slip distribution, moment GPS can resolve nodal plane ambiguity Estimates of finite-fault can be used to estimate deformation, such as tilting of the ground, possible marine navigation hazards due to uplift, life-line continuity,and stress changes Static GPS displacements constrain slip distribution unbiased by rupture velocity assumptions GPS-only solutions provide redundancy check on seismic models Combined GPS and seismic solutions take advantage of complementary constraints Dynamic GPS displacements may be able to determine moment more rapidly than seismic data for great earthquakes Real-time GPS Real-time telemetry via radio, phone lines (frame relay, Quanterra datalogger) Rapid processing (assessing more realtime methods based on Kalman filtering) Estimate of coseismic displacements Estimate of finite-fault model 6

7 Sumatra-Andaman Islands TSUNAMI SYNTHESIS IN REALISTIC OCEANIC MODELS: EXTENDED IN-LAND AND OFF-SHORE SEISMIC SOURCES 7

8 Tsunami modelling in laterally heterogeneous models Modal approach Off-shore seismic sources Green functions approach Near coast and inland seismic sources point and finite sources step and sloping models CONCLUSIONS - 1 analogy between generation of tsunami by inland/coastal seismic sources and diffraction of waves in the vicinity of shadow zone - Huygens principle is formalized in the framework of the Green function method excitation functions for point and finite sources, for infinite ocean layer are different though the main features turn out to be the same for different source mechanisms and depths: tsunami generated by finite source cannot be more intensive than that from point source with the same seismic moment finite source generate more intensive waves at higher frequencies. 8

9 CONCLUSIONS - 2 step model: when source is moving to the boundary excitation of tsunami decreases, and at low frequencies achieves approximately one half of that for infinite layer. At high frequencies intensity of tsunami increases. slope model: replacement of step by slope leads only to appearance of high frequencies in the total wave field. finite source+step model: decay of the tsunami intensity with removal of source toward the land depends on dip, length and depth of the fault. At average the amplitude decays slower, if the fault length is larger and for deeper sources. On the average tsunami amplitude from inland sources, at a distance equal to the source depth, becomes 4-5 times less than the open ocean case. If a source is located directly under the coastline intensity of tsunami is approximately the same as from oceanic source. 9