Talk by Prof Sieh at Temasek Junior College, October 2012


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  • A staggering 900 million people in the Ganges plain, 125 million on Java, 100 million in Sichuan basin
  • E. Coli growing on agar plate (actually different dilutions, but analagous to change over time)
  • Note all the circular mountains on Java; they are volcanoes. The red arrow marks Merapi volcano, north of the Indonesian city of Yogyakarta. In the photo, taken in 2010, Merapi appears in the background, puffing away. The view is from the west atop the great Buddhist temple, Borobudur, built in the 9th century AD during the time of the Sailendran kingdom.
  • Between October and December of 2010, a series of eruptions occurred. The biggest of these, in early November, exceeded any since 1872. As a result nearly 300 people were killed by pyroclastic flows and searing gases. This image shows an infrared image of heat coming off one of the pyroclastic flows.
  • Here’s that Nias coconut grove before AND after the great megathrust earthquake of March 2005. Now the grove is once again high and dry, well above the waves, and islands have once again joined the main island.
  • A map-view history of what we call “super-cycles” of rupture on this section of the Sumatran megathrust
  • Recent detailed estimates of the tsunami caused by the next rupture of the megathrust suggests the following scenario. The darker the color, the higher the depth of the water flowing over the land. In this scenario, a very large percentage of the city will experience dangerous depths of water flow.
  • Source of left photo:
  • The records from this Antarctic ice core shows that CO2 and temperature have varied markedly over the past half million years. The CO2 measurements are made from bubbles of air trapped in the ice and the temperature is inferred from 18O measurements from the ice itself. The past 10,000 years appears to have been the most stable period of the past half million years.
  • Talk by Prof Sieh at Temasek Junior College, October 2012

    1. 1. Earth Science in a Rapidly Changing WorldKerry SiehTemasek JC 12 October 2012
    2. 2. Setting the stage
    3. 3. Mount Sharp, from the rover Curiosity,
    4. 4. Humanity’s time-lineMillions of years ago
    5. 5. Technology has enabled humanity to grow to its current size and Alexander Zehnder, 2011
    6. 6. The Earth is a bit crowded, isn’t it! 1802 1927 1961 1987 20131 billion 2 billion 3 billion 5 billion 7 billion
    7. 7. Four stories to illustrate what earth scientists do to understand our marvelous planet, and how that contributes to safer and more sustainable societiesFidel Costa Judith Hubbard Wang Xianfeng Three assistant professors at the Earth Observatory of Singapore
    8. 8. View towards the east, from Borobudur templeMerapi is just one of many activevolcanoes on Java. It’s particularlyfamous because it sits just north ofthe large Indonesian city of
    9. 9. Fidel Merapi’sCosta biggesthistoricaleruption, in1865
    10. 10. An image of hot pyroclastic flows streaming down the southern flank of Merapi volcano in Nov 2010. This eruption was larger than any since just after 1865, so the mapped hazard zones were exceeded and nearly 300 people died Yogyakarta has been built on the gentle slope of MerapiYogyakarta volcano. Old lahars and pyroclastic flows underlie the city, but none have entered the city in modern times.
    11. 11. FidelCostaWhy was the eruption of November 2010 the biggest since 1872? Professor Fidel Costa
    12. 12. FidelCosta An water-rich crystal in the 2010
    13. 13. FidelCosta Prof Costa uses chemistry, physics and mathematics to understand the “plumbing” of active volcanoes. This photomicrograph shows the concentration of magnesium in anamphibole crystal. Diffusion of the Mg across the crystal occurs at certain rates. By measuring the amount the element has diffused, he can tell how the story of how the crystal moved up
    14. 14. The earthquake cycle and generation of tsunamis
    15. 15. Pre-earthquake (January 2005) Post-earthquake (May 2005)Uplift during the Mw 8.7 earthquake of March 2005
    16. 16. We use GPS to measure tectonic and
    17. 17. Sumatran corals contain a record of largeearthquakes that extends back farther in timethan our modern instrumentsSurveying the corals Cutting them and taking them back to the boat
    18. 18. From Sieh et al., 2008Using the corals, I cantell stories about ancientearthquakes and theirpatterns, even thoughthere were noinstruments there tomeasure theearthquakes. These
    19. 19. A record from corals that goes back 800 years N E X T
    20. 20. A recent effort by German colleaguesA recent effort by I minuteGermancolleagues to 4 minutesestimate tsunami 7 minutesinundation for an 10 minutesearthquake Iforecast in 2008 after arrivalTools needed to atdo this: coastHydrodynamics,a sub-disciplineof physics that ismathematicallyrigourous
    21. 21. Earth Observatory graduate students measuringtsunami levels after the October 2010 tsunami.These “field” measurements are important forconstraining hydrodynamic “models” From a helicopter On the ground
    22. 22. Sediment in a coastal cave in Aceh, northernSumatra, records a 7,000 year long history of
    23. 23. Each of the light-colored layers represents a tsunami. Thedark layers are deposits of bat guano that accumulated onthe floor of the cave between tsunamis.
    24. 24. Using oil and gas exploration techniques tounderstand earthquakes Sichuan basin Professor Judith Hubbard
    25. 25. Chengdu
    26. 26. I think you all areof a changing climate – Observations aware that the Earth’s Greenland melting areaatmosphere and oceans are heating up
    27. 27. Greenland melting in 2012 First time NASA haswitnessed melting across the entire surface of the ice sheetJuly 8, July 12, 2012 2012 Image souce: NASA Light pink = areas of probably melt Dark pink = areas of certain melt
    28. 28. Sea level is rising
    29. 29. Temperatures are increasing in most placesSurface Temperature in 2001–2005 vs. 1951–80 ( C) J. Hansen et al., PNAS 103: 14288-293 (2006)
    30. 30. Wang Xianfeng uses cave formations to study past climate changeMineral-laden rainwater dripsonto the cave floor cave andthen the water evaporates,Calcite (CaCO3) is the mineralleft behind. It forms stalagmitesthat rise from the floor of the
    31. 31. Not all water (H20) is the same. H2180 is heavier than H2160 Most oxygen is 16O. It has 8 protons and 8 neutrons in But about 0.2% of oxygen is 18O. It has 8 protons an neutrons Being heavier, H2180 doesn’t evaporate as easily as its lighter cousin H2160. So rainwater is actually lighter than the seawater from which it comes.Consider now, what happens if this lighter rainfall does not return to the sea, but isinstead deposited in large glaciers. In this case, as the ice accumulates, the water in thesea becomes more and more rich in 18O. That is, its 18O value increases.
    32. 32. From oxygen isotopes in plankton, we know this history of temperature and CO2 for the past half million years! Atmospheric CO2 (ppm) Temperature stability of the past 10,000 yearsSource: Woods Hole Research Center, PEW Center on Global Climate Change
    33. 33. The Chongzhen Drought, at the end of the Ming Dynasty (1637-1643), is known as one of the most severe in Chinese history. It affected more than 20 provinces in N and S China. Huan The prolonged drought g Here is Xianfeng’s record of Chao rainfall changes in China for the helped Li Zicheng organize past millennium, and inferences a popular uprising and with respect to dynastic history overthrow Chongzhen in Zhu 1644. Yuanzhang, River scene at Qingming festival, 1st Ming emperorThe Huang Chao Li ZichengUprising of the870s and 880swas fueled by a At the end of the Yuan Dynastydrought, when there were a series of droughtslocusts swarmed During the Northern Song and a peasant uprising. In 1368the land, and led Strong Monsoon Period, the Zhu Yuanzhang, the leader ofto the end of the Chinese population more than the uprising, took Beijing. HisTang Dynasty tripled, rice became the staple of parents and older brother all the Chinese diet and rice died during the droughts that
    34. 34. One “model” of projected annual average surface temperature change AD 2080-2099 minus AD 1980-1999Average of 21 climate models forced by Scenario A1B. Multiply by ~1.2 for A2 and ~0.7 for B1
    35. 35. How did all the other species of our genus survive on our wild planet over the past couplemillions of years?
    36. 36. They didn’t have agriculture.Agriculture, upon which our civilization isbased, thrived in the relativelystable climate of the past 10,000 years
    37. 37. Will we use the kind of imagination, intelligence, and foresight that got us… or continue to act as if here?our Earth is static andinfinite in size andresources?
    38. 38. Our fate is largely in your hands! Study hard and make a difference.
    39. 39. For those of you interestedin the Earth Sciences, NTU will be offering a major beginning in either 2013 or 2014. We will also be offering a minor for those of you with other academic interests, who wish to become professionals and citizenswith a better comprehension of natural hazards, climate change, earth resources and society
    40. 40. Thank youNew life starting after the 2004 tsunami on an emerged beach on