Detection of volcanic deposits using SAR interferometry | |
| Author | Canisius, Francis Xavier Jorin |
| Call Number | AIT Diss no.SR-03-01 |
| Subject(s) | Volcanic hazard analysis Volcanoes |
| Note | A dissertation submitted in pa1tial fulfillment of the requirements for the degree of Doctor of Technical Science, School of Advance Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation; no. SR-03-01 |
| Abstract | Volcanic disaster causes severe loss of human life and damage to property. The main damage is caused during an eruption and from subsequent erosion of the deposited material. Heavy rainfall in the volcanic area erodes volcanic deposits, mainly pyroclastic and ash deposits, which flow as lahar to the foothill of the mountain. These lahar flows cause drastic damages to the economically important areas. It is therefore important to detect the geographic extent and the height of the volcanic deposits to develop mitigation plans for future disasters. In this study an attempt was made to apply the SAR interferometric technique to map the geographical extent and to estimate the height of the volcanic deposits. Mayon volcano, which is one of the most active volcanoes in the Philippines, was selected as a study area and the deposits by an eruption of Februray1993 were studied. Three pairs of ERS SAR SLC data obtained in 1993, 1996 and 1997 with appropriate baseline were selected for interferometric processing. From these SLC data, SAR intensity images, coherent images and inteferograms were generated using GAMMA software. To map the geographic extent of volcanic deposits, different color composites of SAR intensity and coherence images were examined. A fusion technique was developed to fuse ascending and descending pass SAR intensity and coherent images to eliminate the layover areas. The fused SAR intensity and coherent images were used to map the volcanic deposits on entire mountain. Since all the SAR intensity and coherent images were acquired after 1993 eruption, a SPOT NDVI image of 1992 was used to extract preemption information. To identify the changed area due to 1993 eruption RGB composite of coherent, NDVI and SAR intensity images were developed and interpreted with field information. To estimate the height of the volcanic deposits, the DEM of 1982 derived from topographic map was subtracted from the DEM of 1996 generated from interferogram. To improve the height accuracy of the volcanic deposits, systematic and random error correction models were developed. Then the height of the volcanic deposits was validated using the elevation difference of 1982 and 1999 DEMs derived from topographic maps. The result of this study shows that coherent images generated from the SAR SLC data are valuable sources of information to map volcanic deposits. By using ascending and descending pass data fusion technique, deposits on every side of the mountain can be mapped. Changes due to 1993 eruption can be identified using the RGB composite of coherent, NDVI and SAR intensity images. Though a DEM was successfully generated from the tandem dataset of ERS-1/2 with 94 m baseline, the accuracy of the elevation difference is not sufficient to estimate the height of the volcanic deposits. By applying systematic and random error correction, 5 to 10 m accuracy, which is practically acceptable level for estimating the volume of volcanic deposits, could be achieved. The methodology developed in this study to detect volcanic deposits using SAR interferomehy provides a new alternative for monitoring the effect of volcanic activity. |
| Year | 2002 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation; no. SR-03-01 |
| Type | Dissertation |
| School | School of Advanced Technologies (SAT) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Space Technology Application and Research (SR) |
| Chairperson(s) | Honda, Kiyoshi;Tokunaga, Mitsuharu; |
| Examination Committee(s) | Murai, Shunji; Tawatchai Tingsanchali; Apisit Eiumnoh; |
| Scholarship Donor(s) | -; |
| Degree | Thesis (Ph. D.) - Asian Institute of Technology, 2002 |