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Draft volcano primer: Mt. Pinatubo and Taal volcanoes, the Philippines

Draft volcano primer: Mt. Pinatubo and Taal volcanoes, the Philippines. Mt. PINATUBO ERUPTIONS June 1991. Prior to eruption. Fumaroles on flanks, April 1991. June 12th, 1991 eruption. Giant pyroclastic flows, June 15th 1991 form off of collapsing eruption column.

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Draft volcano primer: Mt. Pinatubo and Taal volcanoes, the Philippines

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  1. Draft volcano primer:Mt. Pinatubo and Taal volcanoes,the Philippines

  2. Mt. PINATUBO ERUPTIONSJune 1991

  3. Prior to eruption

  4. Fumaroles on flanks, April 1991

  5. June 12th, 1991 eruption

  6. Giant pyroclastic flows, June 15th 1991form off of collapsing eruption column

  7. The view from space via theJapanese GMS-5 geostationary satellite

  8. Early effects on the ground

  9. Sediment-laden rivers destroy roads & bridges

  10. Major landscape changes: Pyroclastic flows in-filled pre-existing river valleys (the peaksin two views below are the same feature)

  11. AIR PHOTOS(recent views)

  12. Summit caldera of Mt. Pinatubo, Nov. 1999.The low-point in the rim is a future hazardas the lake will eventually over-top here.

  13. Typical view of eastern flank, Nov. 1999

  14. Erosion of ignimbrite fan onNW. flank, November 1999

  15. Erosion of river valley on thenorthern flank, Nov. 1999

  16. Sediment fills valley floor downslope on lower E. flank November 1999

  17. Detail of lahar-filled valleyE. flank, Nov. 1999

  18. GROUND PHOTOS

  19. Exploring eroded valley, SW flankNov. 1999

  20. Crossing the sediment-laden streams is a real challenge! So much sediment is in these streams that they easily knock you over.

  21. Valley erosion can be extreme in places: Up to 20 m down-cutting during one typhoon! This mosaic shows the remains of the 1991 deposit (white unit) that has been cut by younger flash floods

  22. Erosion of 1991 deposit

  23. Vegetation is starting to grow back on westernfan. Summit of Mt. Pinatubo in background

  24. “LAHARS” (MUDFLOWS) ANDTHE RESULTANT DAMAGE

  25. Major changes in valley floor elevation aftersingle lahar has formed after typhoon.

  26. The impact on villages within the path of a lahar can be extreme

  27. While old houses are buried, new homesare built on stilts to try to avoid the next lahar

  28. An old church has been partially-buried sothat you now enter on the 2nd floor. RonnieTorres shows the church prior to the lahars.

  29. Giant dikes made from old lahar and covered withconcrete now try to protect areas from new lahars

  30. The contrast between areas protected by thedikes and unprotected is striking -- and it’sall an issue of insurance for redevelopment!

  31. Some homes, once buried by lahar, andnow being exposed by recent erosion

  32. REMOTE SENSINGDATA

  33. Landsat 7Path 116Row 50

  34. RADARSAT radar backscatter imageof Mt. Pinatubo, February 1998

  35. SPOT image of Mt. Pinatubo December 1991

  36. Comparison of NW Summitfrom SPOT dataobtained between1991 and 1998Red showsvegetation,the ash depositsare light blue Summit is atlower right

  37. Changes in Mt. Pinatubo lahar deposits. Lower Pasig-Potrero River 1991 - 1996

  38. TAAL VOLCANO(just south of Manila)

  39. RADARSATscansar beam 1(50 m/pixel)image of TaalVolcano andsurroundingarea

  40. View of Lake Taal and Volcano Island from north rim, Nov. 1999

  41. NW corner of Lake Taal

  42. Over 4,000 people live without permission on the shores of Volcano Island

  43. In the event of an eruption of Taal, all the population would have to leave Volcano Island via small boats

  44. View of the volcanic lake in middle of Volcano Island (middle of Lake Taal)

  45. In Fall 1999, this vent on Volcano Island was actively geysering.

  46. Close-up viewof recently activevent on VolcanoIsland, in themiddle of Taal Volcano

  47. Even around the rim of Lake Taal, people and their fish farms are at risk from tsunamis generated by eruptions.

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