1. Geology and Remote Sensing of Mt. Pinatubo & Taal Volcanoes, the Philippines Peter Mouginis-Mark University of Hawaii pmm@pgd.hawaii.edu Work funded by NASA’s Solid Earth and Natural Hazards Program

2. LOCATION OF VOLCANOES IN THE PHILIPPINES

4. Landsat 7 coverage (obtained over 3 different days)

5. Mt. PINATUBO ERUPTIONS June 1991

6. Prior to eruption

7. Fumaroles on flanks, April 1991

8. June 12th, 1991 eruption

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

10. The view from space via the Japanese GMS-5 geostationary satellite

11. Early effects on the ground

12. Sediment-laden rivers destroy roads & bridges

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

14. AIR PHOTOS

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

16. Typical view of eastern flank, Nov. 1999

17. Erosion of ignimbrite fan on NW. flank, November 1999

18. Erosion of river valley on the northern flank, Nov. 1999

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

20. Detail of lahar-filled valley E. flank, Nov. 1999

21. GROUND PHOTOS

22. Exploring eroded valley, SW flank Nov. 1999

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

24. 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

25. Erosion within the 1991 deposit

26. Erosion of 1991 deposit

27. Amazing landscapes!

28. Vegetation is starting to grow back on western fan. Summit of Mt. Pinatubo in background

29. “LAHARS” (MUDFLOWS) AND THE RESULTANT DAMAGE

30. Major changes in valley floor elevation after single lahar has formed after typhoon.

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

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

33. An old church has been partially-buried so that you now enter on the 2nd floor. Ronnie Torres shows the church prior to the lahars.

34. Giant dikes made from old lahar and covered with concrete now try to protect areas from new lahars

35. The contrast between areas protected by the dikes and unprotected is striking -- and it’s all an issue of insurance for redevelopment!

36. Some homes, once buried by lahar, and now being exposed by recent erosion

37. REMOTE SENSING DATA

38. Landsat 7 Path 116 Row 50

39. RADARSAT radar backscatter image of Mt. Pinatubo, February 1998

40. SPOT image of Mt. Pinatubo December 1991

41. RADARSAT radar backscatter image of western fan of Mt. Pinatubo

42. Clark Air Base: RADARSAT standard beam data set (25 m/pixel)

43. SPOT data of Mt. Pinatubo summit area soon after the eruption

44. Comparison of NW Summit from SPOT data obtained between 1991 and 1998 Red shows vegetation, the ash deposits are light blue Summit is at lower right

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

46. ERS-1 radar backscatter image of Pasig-Potrero River showing low-backscatter lahar deposits

47. Shaded relief image of lahar fans SE of Mt. Pinatubo summit from NASA TOPSAR topographic data

48. Nighttime Landsat 7 thermal data of Mt. Pinatubo shows warm streams

49. TAAL VOLCANO (just south of Manila)

51. RADARSAT scansar beam 1 (50 m/pixel) image of Taal Volcano and surrounding area

52. Space Shuttle radar (SIR-C/X-SAR) multi-wavelength (3, 5.6 and 24 cm) image of northern part of Taal Volcano

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

54. NW corner of Lake Taal

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

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

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

58. In Fall 1999, this vent on Volcano Island was actively geysering. It was quiet in November 1999.

59. Close-up view of recently active vent on Volcano Island, in the middle of Taal Volcano

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