Quantification of relative sea level change along the coastline of Oman (Arabian Sea)
Final Report Abstract
The coast as the interface between the sea and the land is undergoing constant changes. These changes may be fast, when caused by extreme wave events such as tsunamis or hurricanes. Both natural processes are calamities known to have affected Oman’s coastline in the recent past. On the other hand, coastal changes might be slow and not visible for the human eye. Nevertheless, such incremental processes are important to understand and quantify as the velocity of these (mm/year) is of the same order of magnitude as changes observable, caused by global sea level rise due to climate change. The local impact of such long-term trends becomes only obvious if the local, regional factors are known: The impact of a rising sea level is much more severe along a sinking coastline when compared to an area that is uplifting, where the net-effect might be zero. We analysed a staircase of marine terraces along the coastline of Oman. We are able to show that different processes contribute to the uplift, a very interesting one being rock alterations that occurred in wet periods of the recent Earth history. The devastating effects of tsunamis along coastlines became apparent after the 2004 Indian Ocean Tsunami and the 2011 Tohoku event. Both tsunamis were triggered by submarine earthquakes along subduction zones. Due to the geographic location, the impact of the 2004 event was minor in Oman and the 2011 waves did not reach the coastline at all. However, the coastline under study here is exposed to the Makran Subduction Zone. The hazard potential of this zone was/is still enigmatic or unknown. We were successful in gathering information on paleo-tsunami along the coastline. The last major tsunami caused by a subduction earthquake within the Makran Subduction Zone occurred in the night from 27. - 28. December 1945. This event had an impact along most of Oman’s coastline. We reconstructed maximum tsunami wave heights in the range of 2-3 m for the coastline under study. The coastal morphology is indicative of more severe events in the past. This evidence is mainly seen in boulder deposits which were intensively analysed in-between Quriyat and Sur. The size and the distribution of these indicate that the tsunami of 28.12.1945 is clearly not the worst case scenario. Larger waves appear plausible and we conclude that 15 m waves are possible, a major tsunami of this magnitude reached the coastline 1 000 years ago. The return period of such events seems rather long.
Publications
- (2018): Tsunami and storm sediments in Oman: Characterizing extreme wave deposits using terrestrial laser scanning. - Journal of Coastal Conservation
Schneider, B., Hoffmann, G., Grade, J., Falkenroth, M.
(See online at https://doi.org/10.1007/s11852-018-0663-4) - (2019): Beachrock as sea-level indicator – a case study from the coastline of Oman (Northern Indian Ocean). – Quaternary Science Reviews, 206: 81-98
Falkenroth, M., Schneider, B., Hoffmann, G.
(See online at https://doi.org/10.1016/j.quascirev.2019.01.003) - (2019): Geoarchaeological Evidence for the Decline of the Medieval City of Qalhat, Oman. – Open Quaternary. 5: 8, pp. 1–14
Ermertz, A.M., Kázmér, M., Schneider, B., Adolphs, S.K., Falkenroth, M., Hoffmann, G.
(See online at https://doi.org/10.5334/oq.56) - Holocene tsunamigenic earthquakes in the western Makran Subduction Zone. – Marine Geology
Hoffmann, G., Grützner, C., Schneider, B., Preusser, F., Reicherter, K.
(See online at https://doi.org/10.1016/j.margeo.2019.106068) - Quaternary uplift along a passive continental margin (Oman, Indian Ocean). – Geomorphology
Hoffmann, G., Schneider, B., Mechernich, S. Falkenroth, M., Ermertz, A., Dunai, T. Preusser, F.
(See online at https://doi.org/10.1016/j.geomorph.2019.106870)
