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.