1. The Maldives: Sea-levels, Tsunamis and Coastal change
Sue Dawson
&
Niklas Mörner

2. Islands are no more than 1.5 m above sea level

3. The Maldives

4. Satellite photo of the
Atolls making up the
Maldives

5. Some
1200
islands
Welcome to the Maldives
Grouped in
some 20
larger
atolls

7. “Queen’s Bath” (Hithadoo Island, Addoo Atoll)
Shore terrace 400–800 BP: +60 cm
High-tide level 1790–1970: cm
High-tide level today
(1) Mean-tide level today

8. A sea level fall ~1970-1975 lowering of the erosion level
building out of lower shoreplane
owergrowing of old surface
weathering of old surface
The lowering was in the order of
20-30 cm
(probably an effect of increased evaporation, decreased precipita-tion and/or changed monsoonal regime)
The Maldives, 2002

9. The coral is cut and dated at 2 levels. (2) = 1585 +35 BP
Example of records of short high sea levels.
This coral, today 5-10 cm above mean zero,
and “in situ” requites a water depth of ~60
cm (according to Laborel), implying a
higher sea level of about +70 cm.
The coral is cut and dated at 2 levels.
(2) = BP
(1) = BP

10. Goidhoo Atoll
Fen cores

11. Sea level oscillations in the last millennium (cores from two fens)
The 2 swamps became lakes in ~1790 and both dried up in ~1970
NB. Peat and shell dates differ by 350 years, a good measure of the local “sea correction”

13. The new sea level curve of the Maldives (Mörner, 2007) recording a number of oscillations driven by the redistribution of ocean water masses. The base line seems to peak at around 1300 BP (excluding any Mid-Holocene maximum as predicted by the loading models).

15. It shows variations – ups and downs – but no trend.
The combined observational records (in mm/year) for the last 300 years.
It shows variations – ups and downs – but no trend.
For year 2100, INQUA gives predictions in line with this record,
whilst the IPCC scenarios lie far above – way off – observational data

16. The ”flooding scenario” of IPCC does not concur with observational sea level facts. Therefore, it must be called-off as a mistake.
Today, we favour a 2100 value of +5 cm +15 cm

18. The Maldives
Earthquake
Epicentre
2500 km
3 hrs travel time

19. Satellite image
2 hrs after the
earthquake

20. Tide data for Male
and Gan

21. The Maldives Population: 290,000 Total number of islands 1,192
Number of inhabited islands:199
Flooding Status
Only 9 islands had no flooding
69 islands completely flooded

22. Sand deposits across the airport

23. Gan, Laamu Atoll: Maldives tsunami sediment thickness 30cm
Finer sediment than the beach

24. Particle Size Analysis
Well sorted beach sands differ
From the overlying tsunami deposits

25. Isdhoo, Laamu Atoll, 2cm tsunami sediment
And PSA profiles

26. Sediment plumes

27. Sediment plumes across the islands: protection
of the land from the reefs located up to 1km
offshore

28. Clear sediment plumes into the lagoon

29. Sediment plumes through to the lagoon inside the atoll (distance c
Sediment plumes through to the lagoon inside the atoll (distance c. 500m.)

30. Coral debris plumes in the lee of trees and vegetation

32. Erosion scarp on the leeward side of the islands
Tsunami deposits
Overlie the beach sands

33. Male
Highly built up- Male
Was severely flooded

34. Sea level oscillations in the last millennium (cores from two fens)
The 2 swamps became lakes in ~1790 and both dried up in ~1970
NB. Peat and shell dates differ by 350 years, a good measure of the local “sea correction”

35. Ostracod and Foraminifera
Spiroloculina
Quadracythere sp.
Quinqueloculina
Elphidium sp.

36. Potential for chronology
of extreme events
Laamu Atoll

37. Table 1. Submarine shedding of sand into caves with radiocarbon dating of shells and coral after subtraction of 350 years for regional “sea correction”.

38. Tsunami in AD 1733: (1) in fen records (left), (2) in submarine caves (right) and (3) in a historical record of ”a disastrous flooding in 1733.

39. The Lisbon earthquake–Tsunami is classical
and similar events are bound to re-occur in the near-future

41. The reality is much more complicated:
When a coastal segment experiences erosion, a ”sea level rise” is often advocated.
The reality is much more complicated:
in fact, a sea level lowering generally causes more erosion!
The clue is often what actually is to be found on the lee-side