A new review of tsunami hazards concludes that the 2004 catastrophe was far from the worst possible in many Indian Ocean borderlands - and notes that warning systems to guard at-risk populations are still lagging.
Costas Synolakis, director of the University of Southern California Tsunami Research Center is co-author of "Far-Field Tsunami
Hazard From Mega-Thrust Earthquakes in the Indian Ocean," just published in the Geophysical Journal International.
Synolakis and co-author Emile Okal of Northwestern University evaluated all known potential tsunami-generating sources in the vast area between Africa, Asia, Australia and Antarctica, and then calculated the impact of the tsunamis they can generate, should they rupture. Their paper presents the geographical distribution of risk.
The pair examined eight scenarios, two along Southern Sumatra (in Indonesia), two in the North Andaman segment of the Sumatra Subduction Zone, two sources along the Makran Subduction Zone (south of western Pakistan) and two sources south of Java. (Indonesia)
According to Synolakis, a professor in the USC Viterbi School of Engineering's Sonny Astani Department of Civil and Environmental Engineering, "the most important lesson from the scenarios we investigated is that the patterns of far-field maximum amplitudes predicted by our simulations will not be a repeat of those observed in 2004." The differences result from differences in the directions in which the disturbances propagate, "and in many instances the results are counterintuitive."
Synolakis expressed high confidence in the reliability of the projections. "Even if the earthquakes, as they materialize in the future, have geometric characteristics that are slightly different from our hypothetical scenarios, the far field impact projections are robust to small initial perturbations arising from uncertainty in the rupture characteristics."
Among the paper's conclusions:
The impact in the mid-ocean Maldive Islands from all scenarios appears to be similar or less than what was observed in 2004 - however the low-lying structure of the islands makes them more difficult to evacuate than other risk sites.
The impact in Madagascar and the Mascarene Islands (Mauritius, Rodrigues and Réunion) and the Seychelles could be far greater than in 2004, particularly from earthquakes in Southern Sumatra and in South Java. Madagascar is found particularly vulnerable from South Sumatran tsunamis.Africa suffered in excess of 300 deaths in 2004, 300 of them in Somalia. Its east coast is vulnerable from south Sumatran tsunamis and in particular, Somalia remains at high risk due to the focusing effect of the Maldives ridge.
The Comoro islands located between Tanzania and Madagascar would probably be affected more severely than in 2004.
Large earthquakes in south Java would generate substantial levels of destruction in Northern Australia, despite the sparse level of development there.
The Strait of Malacca area appears more vulnerable than in 2004, from earthquakes in the North Andaman. Bali and Lombok and could be severely affected by large events in south Java. In fact Bali was affected by the 1994 tsunami, whose trigger was smaller than the ones envisioned here.
The Kerguelen Islands (49.5◦S; 69.5◦E), part of the French Southern and Antarctic Territories, are highly vulnerable. Other than the North Andaman scenarios, practically all other events affect the Kerguelens, where apparently the 2004 tsunami did not cause damage. The much larger offshore heights the simulations predict would put the scientific base there (60-100 persons) at risk.
Many of these scenarios have never been examined before. Synolakis' USC colleague Jose Borrero and others examined the local impact from south Sumatran scenarios in a 2006 paper in the Proceedings of the National Academy of Sciences. Synolakis and Okal concentrated on basin-wide impacts not studied earlier.
The impact to the eastern coast of India and in Myanmar and Bangladesh from the North Andaman scenarios was examined in a paper recently published in Nature by Phil Cummins (2007) of Geoscience Australia. The impact the new paper predicts is slightly different, Synolakis says, but only in the geographical distribution of the carnage.
According to that paper, the Makran Coast of Baluchistan constitutes a subduction zone along which the Arabian plate sinks under the Eurasian one. This was the site of a major earthquake on 1945 November 27, which was accompanied by a significant regional tsunami, with run-up in the five to ten meter range.
Synolakis and Okal, who is a professor in Northwestern's Department of Earth and Planetary Science, examined different rupture scenarios and their affect on the Makran coast, Oman and the west coast of India. "They are substantial and need more detailed study," Synolakis said, making reference to a documented catastrophe that occurred 24 centuries ago: "While the tsunami impact could be inferred from Pliny's reports of the adventure sof the fleet of Alexander the Great returning from India at the Straits of Hormuz in 434 AD, it has not yet been examined to the extent it deserves given the commercial and military value of the Straits.
Synolakis and Okal agree with Cummins about a critical need for the area: a warning net.
"It is quite clear that a tested and true tsunami early warning system as now works in the Pacific by the Pacific Tsunami Warning Center needs to be urgently implemented in the Indian Ocean," said Synolakis. "This system should include hundreds of pre-computed detailed scenarios of inundation for all Indian Ocean nations to facilitate emergency planning for evacuation should any of these scenarios materialize. Public education is a must and local people and visitors should be made aware of tsunami hazards, no matter how unlikely they may be, just us Hawaii and Oregon are already doing."
Synolakis and Okal began work on the project almost in the immediate aftermath of Sumatra 2004 and was completed last year.
"Our work was triggered from three different two week classes we taught for UNESCO in 2006/2007 on tsunami hazard mitigations in the Indian Ocean," said Synolakis. "More than eighty professionals attended having been nominated by their governments and we tried to show them how to assess with us the local impact from adjacent sources. We tried to guide them towards understanding and evaluating transoceanic impact, but the computational tools they had then were just not optimal.
"The work we present here extends the synthesis of hundreds of inundation projections done by our students in these classes, with varying degrees of success. However, all the specific scenarios we used are the synthesis of extensive literature and archive review, a synthesis of the preliminary material we developed in the UNESCO classes and of course all the computations are new."
The National Science Foundation and the European Union - via a Transfer Grant - supported the research.
Eric Mankin | EurekAlert!
Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute
Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine