The Ca and Mn enrichment is a characteristic signature indicating marine origin of these sediments. Though Na and K ions constitute a significant part of the seawater, their depletion in the tsunami deposits is suggestive of chemical alteration through ion-exchange due to leaching and prolonged burial. Modelled calendar ages and probability distributions of stratigraphy exposed in geoslices and trenches excavated along WNW-ESE transect at Badabalu.
The ages are calculated and modeled using OxCal version 4. Areas with white outlines indicate the probability distributions functions PDFs of calibrated radiocarbon ages.
Gray areas represent posterior PDFs. Quantitative analysis of foraminifera obtained from Units b, d, e, g, n and p indicated two distinct biofacies suggestive of marginal marine environments and sediment provenance: Biofacies-I: subtidal, and Biofacies-II: intertidal Supplementary Data S3 ; Figs. Unit-n corresponds to the Biofacies-I, comprises majority of subtidal species like Rotalia sp. Whereas, Unit-p shows dominance of Ammonia beccarii - an intertidal species Supplementary Fig.
Foraminifera assemblages from Units b, d, and g also show same kind of species and taphonomy. These units also show high percentage of abraded and fragmented foraminifera test Supplementary Fig. The peaty soil Unit-e with Elphidium discoidale suggests shallow intertidal-beach environment. The change in the environment from intertidal-beach to wetland is attributed to interseismic uplift.
This further strengthen our interpretation that Units b, d, g, n and p were deposited by tsunami events, which transported and deposited forams from different depths Supplementary Data S3. All ages were calibrated and modelled with OxCal v. Composite stratigraphic-section constructed using the litho-sections obtained from geoslices and trenches at Badabalu, south coast of Andaman Island. Although, the age obtained from tsunami sand was the most reliable, the estimated age gave an offset of years.
The major oxides and trace elemental abundances in sediments from Badabalu revealed characteristic signatures similar to that observed in other global tsunami deposits Fig. Tsunami and non-tsunami deposits i. Interestingly, the tsunami deposits in the bottom section are thicker compared to those in the upper portion.
It is possible that the some of the distinct geochemical signatures in these older tsunami deposits are disturbed due to prolonged burial and leaching On the other hand, all the tsunami Units b, d, g, l, n and p contain distinctly higher CaO and MnO than the other terrigenous Units a, c, e, f, h, i, j, k, m, o, and q.
High abundance of CaO and MnO is a characteristic signature in tsunami deposits The major oxides abundances further strengthen our interpretation that Units b, d, g, l, n and p are of marine origin, and deposited inland during tsunami events. Thus, characteristic geochemical signatures in Units b, d, g, l, n and p further affirms their tsunamigenic origin. The signatures of Sumatra-Andaman earthquake and tsunami were considered as a modern analogue to distinguish the role of local and distant source earthquakes towards the deposition of tsunami deposits.
At Badabalu, we found relatively thicker and coarser deposits Units l, n and p as compared to Unit-b deposited by tsunami. The presences of thicker deposits could be attributed to the paleo-shoreline morphology. Possibly at the time of deposition the beach-ridge and associated back-marsh were located farther inland relative to the present coastline configuration, with deposition taking place in a swale or back-marsh area.
Further, the coarser and thicker deposits could be related to tsunami events with much higher energy conditions, which was possible by a major earthquake triggered along the Andaman-Arakan Segment, suggesting a local earthquake. This is well justified comparing the tsunami deposit at the same location. Therefore, we infer that the thicker and coarser units viz.
Units l, n and p were deposited by the local-source earthquakes those occurred along the Andaman-Arakan Segment. Paleo-tsunami and paleoseismic events identified in the present study were correlated with the reported events from the areas adjoining Indian Ocean Supplementary Table S1. The present study from Badabalu revealed evidence of at least seven tsunami events in the last years Figs.
These events were bracketed based on their modelled calendar ages 22 , 23 Tables 1 and 2 ; Supplementary Tables S4. We correlate this event with the Mw 7. This was a local event that occurred along the Andaman segment, generated 0. Signatures of liquefaction and tsunami deposit were also reported from Mitha-Khadi around Port Blair in Andaman Island 6.
However, no clear evidence of land-level change was found at the present study site. This suggest that Andaman was at the southern tip of this rupture. The event correlates with the historic earthquake of CE Figs.
BP from Thailand Considering its wide-spread effect we suggest that this event was triggered along the Andaman Segment and was comparatively larger than CE Event II , inflicting wider effect in the Indian Ocean.
BP; CE — Also, signatures of subsidence and tsunami deposit during CE — have been reported from the south Andaman, as well as an uplift from Hut Bay and north Andaman 11 , This was a mega earthquake sourced locally along the Andaman segment and resulted in a transoceanic tsunami 3. Due to a wider age bracket it is difficult to correlate this event with a particular event reported from other adjoining areas in the Indian Ocean. Nevertheless, it may be correlated with the BCE — — cal.
BP; BCE — BP tsunami event reported from Indonesia Because we found this tsunami deposit in only one geoslice Fig. This discontinuous stratigraphic record could be attributed to erosion due to one of the possibilities: a coseismic uplift or gradual uplift during inter-seismic period along the up-dip portion of the subducting plate or upper plate fault.
But no upper plate fault from this region has been reported; b Relative Sea Level RSL fall which accelerated erosion of the stratigraphic sequence. Further, Brill et al. Dura et al. The lower portion of the stratigraphic section comprising Units l to r reveals stacked sequence of peaty units wetland soils; Units m, o and q and tsunami deposits Figs.
The Unit-k comprising fine-medium silty-sand suggests basin-fill under sub-tidal condition followed by a gradual uplift during inter-seismic period. The peaty soil Unit-j indicates the formation of wetland soil at or above mean sea-level. The presence of Unit-h peaty soil suggests that the area was at or above mean sea-level. We infer that the area emerged from deeper environment sub-tidal around this time.
The upper portion of the stratigraphic section, Unit-b marks the tsunami, Units d and g represents tsunamis during the recent historic time Figs. Unit-f with fine sand suggests that the area was under the influence of sub-tidal environment, whereas Units e and c peaty soils indicate that the area was at or above mean sea-level. Possibly the area experienced subsidence during these earthquakes and recovered during post-seismic period, which eventually facilitated the formation of wetland soils and vegetation growth.
The area remained submerged for substantially longer span during inter-seismic period as indicated by a thick fine silty-sand Unit-i Figs. A long-term inter-seismic subsidence implies a huge strain accumulation. However, couple of large magnitude earthquakes viz. The CE event was a local event having its rupture along the Andaman Island. Hence, we conclude that the Andaman Segment has enough accumulated strain to trigger a mega- tsunamigenic subduction zone earthquake in near future.
A years stratigraphic gap add to the uncertainty associated with the estimation of the recurrence of tsunamigenic earthquakes. However, years of continuous sequence suggests a recurrence of — years for a mega-earthquakes along subduction zone like the — CE 3 , — CE and the Sumatra Andaman earthquake having different source.
A shorter interval of 80— years is inferred for the large earthquakes like , and CE. Google Earth images pre and post earthquake were used to identify the location that experienced land-level change and having a shoreline configuration with beach-ridge-swale topography, which are ideal for the preservation of tsunami deposits Supplementary Figs.
We identified typical signatures of paleo-earthquakes and paleo-tsunamis from shallow stratigraphy at Badabalu Figs. The area is marked by typical beach ridge-swale-beach ridge topography, with a distinct back-marsh Figs. Such geomorphic setting is considered to be an ideal sites for the preservation of tsunami deposits Three 1—1.
All exposed stratigraphic sections studied are perpendicular to the shoreline. Lithounits in the exposed sections were classified based on their sedimentological characteristics in the field e. To further strengthen our interpretations towards differentiating tsunami and non-tsunami deposits, we preformed geochemical and micro-fossil analysis Fig. The foraminifera analysis was carried with a standard methodology Supplementary Data S3 ; Fig. We collected sediment samples from the exposed trenches as well as geoslices obtained from Badabalu site Figs.
This is done to get rid of carbonates and organic matter from the sediments. Dried samples were then sieved to obtain 90— um grain fractions of which only 90— um fraction size was used for further analysis.
The quartz and feldspar were isolated with the help of Frantz magnetic separator with constant current of 1. These grains were then mounted on 9. All the processing was carried out in the laboratory controlled red light environment. Ages were calibrated and modelled with Bayesian analysis in the program OxCal v. To examine the geochemical signatures of the near-surface coastal stratigraphy from Badabalu site, we analysed 16 samples from 17 litho-units Units a to q, except from Unit-o for major oxides and selected trace element abundances Fig.
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J Disaster Res , 8: — Download references. The author acknowledges Drs. Shingo Watada and Mohammad Heidarzadeh for their reviews of the manuscript before submission. Valuable comments and suggestions by two anonymous reviewers also improved the paper.
You can also search for this author in PubMed Google Scholar. Correspondence to Kenji Satake. Reprints and Permissions. Satake, K. Advances in earthquake and tsunami sciences and disaster risk reduction since the Indian ocean tsunami. Download citation. Received : 09 September Accepted : 04 November Published : 13 November Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article.
Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search all SpringerOpen articles Search. Download PDF. Review Open Access Published: 13 November Advances in earthquake and tsunami sciences and disaster risk reduction since the Indian ocean tsunami Kenji Satake 1 Geoscience Letters volume 1 , Article number: 15 Cite this article 15k Accesses 38 Citations 27 Altmetric Metrics details.
Figure 1. Full size image. Review of developments in seismology Can we forecast earthquakes and tsunamis in advance? Figure 2. Review of developments in tsunami science Tsunamis are generated by submarine earthquakes, volcanic eruptions or landslides. Figure 3. Various types of instruments designed to measure tsunami. The Tohoku earthquake and tsunami A giant earthquake occurred off the northern coast of Honshu, Japan, on 11 March Figure 4.
Toward tsunami disaster risk reduction Despite advances in natural science on hazards, why do disaster losses continue to increase? Figure 5. Conclusions 1 The Sumatra-Andaman earthquake, the largest event in the last 40 years, caused the worst tsunami disaster in countries around the Indian Ocean. References 1. Article Google Scholar 6. Article Google Scholar Google Scholar Google Scholar Download references.
Acknowledgements The author acknowledges Drs. Additional information Competing interests The author declares that he has no competing interests. About this article. Cite this article Satake, K. Copy to clipboard.
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