1. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Case study: volcanic hazards Introduction to case study: Measuring erosion and sedimentation from multi-temporal DTM’s: Pinatubo volcano. Elaboration of geomorphologic maps for the pre- and post-eruption situations, up till 1993. This was done in order to evaluate the changes in the catchment areas and their significance in producing lahars. Creation of digital terrain models for each year, from which the thickness of pyroclastic flows, and the yearly eroded volume can be calculated.

2. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Study area: Pinatubo

3. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Pyroclastic flow deposits Severe erosion Lahars

4. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Modelling erosion at Mt Pinatubo

5. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Pre eruption DTMPost eruption DTM Post lahar 1991 DTM Post lahar 1992 DTM Post lahar 1993 DTM

6. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Digital Elevation Models DTMpreThis is a DEM before 1991 DTMerpThis is a DEM showing the situation shortly after the eruption DTM91This is a DEM after the first rainy season DTM92After the second rainy season DTM93After the third rainy season Plus catchment maps and drainage maps

7. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Flowchart volume calculation

8. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Modelling erosion at Mt Pinatubo

9. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Cross sections

10. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 After eruption Thickness:= DTMERP-DTMPRE positive values: pyroclastic flow deposits negative values: crater Volume per pixel: Volume=Thickness*Pixelsize Total Volume in map: Aggregate volumes per pixel

11. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004

12. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Catchment change after eruption Total size smaller ?! Large change from Sacobia to Abacan

13. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Volume calculations Volume calculations per catchment based on pre- and post eruption catchment boundaries.

14. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 After first rainy season Total erosion Ero91:=if(dtm91<dtmerp,dtmerp-dtm91,0) Erosion in PF deposits: Eropf91:=if((ero91>0)and(dtm91>dtmpre),dtmerp- dtm91,0) Erosion in other deposits: Eroot91:=if((ero91>0)and(dtm91<dtmpre),dtmpre- dtm91,0)

15. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 After first rainy season Sedimentation in 1991: Sed91:=if((dtm91>dtmerp,dtm91-dtmerp,0) Remaining PF material in 1991: Rem91:=if(dtm91>dtmerp,dtmerp- dtmpre,if(dtm91<dtmpre,0,dtm91-dtmpre) or Rem91:=(dtm91-dtmpre)-sed91 and use only the positive values

16. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Resulting maps

17. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004

18. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Catchment change after first rainy season Abacan back to Sacobia : stream piracy

19. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Volume calculations

20. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 After second rainy season Total erosion Ero92:=if(dtm92<dtm91,dtm91-dtm92,0)

21. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 After second rainy season Erosion in PF deposits: Eropf92:=if((ero92>0)and(dtm92>dtmpre)and(dtm92<dt merp),dm91-dtm92,0) Erosion in other deposits: Eroot92:=if((ero91>0)and((dtm92 dtm erp),dtm91-dtm92,0)

22. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 After second rainy season Sedimentation in 1992: Sed92:=if((dtm92>dtm91,dtm92-dtm91,0) Remaining PF material in 1991: Rem92:=if(dtm92>dtmerp,dtmerp- dtmpre, if(dtm92 dtmp91, dtm91 - dtmpre,dtm92-dtmpre)) or Rem92:=(dtm92-dtmpre)-sed92 and use only the positive values

23. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004

24. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Catchment change after second rainy season Minor changes

25. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Volume calculations

26. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 After third rainy season Total erosion Ero93:=if(dtm93<dtm92,dtm92-dtm93,0)

27. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 After third rainy season Erosion in PF deposits: Eropf93:=if((ero93>0)and(dtm93>dtmpre)and(dtm93<dt merp),dm92-dtm93,0) Erosion in other deposits: Eroot93:=if((ero93>0)and((dtm93 dtm erp),dtm92-dtm93,0)

28. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 After third rainy season Sedimentation in 1993: Sed93:=if((dtm93>dtm92,dtm93-dtm92,0) Remaining PF material in 1993: Rem93:=if(dtm93>dtmerp,dtmerp-dtpre,if(dtm93 dtmp92,dtm92- dtmpre,dtm93-dtmpre))

29. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004

30. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Catchment change after third rainy season More change Abacan - Sacobia Large change Sacobia - Pasig due to secondary explosion & stream piracy

31. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004 Volume calculations

32. International Institute for Geo-Information Science and Earth Observation (ITC) ISL 2004