Identifying Temporal Change of Merapi Identifying Temporal Change of - PowerPoint PPT Presentation

Identifying Temporal Change of Merapi Identifying Temporal Change of Merapi Eruption Type by Satellite SAR Data Eruption Type by Satellite SAR Data Analysis Analysis Asep SAEPULOH 1 , Katsuaki KOIKE 1 , Makoto OMURA 2 , Masato IGUCHI 3 1 Department of Life and Environmental Sciences, Kumamoto University 2 Department of Environmental Science, Kochi Women’s University 3 Disaster Prevention Research Institute, Kyoto University

Study site Study site Landsat ETM+ B:457 � Located in Central Java, Indonesia. INDONESIA � One of 129 the most active volcanoes. Mt. Merapi

Detection of Active Volcano Topographical Detection of Active Volcano Topographical Change of Mt. Merapi Change of Mt. Merapi G. MERAPI Photos: Undertoad, 2006 Data: Normal Active � Ten SAR data set � Five sets JERS-1 => Intensity Eruption Stage � Five sets Radarsat => Brightness Photos: Undertoad, 2006

DATA SELECTION DATA SELECTION JERS-1 Frequency 1.275 GHz Capability HH Polarization Right-looking (North) Range/Azimuth res. 18 m RADARSAT-1 SAR Frequency 5.3 GHz Capability HH Polarization Right-looking (North) Range/Azimuth res. 8-9 m

Problem Definition � How to detect the volcanic deposits due to the bad atmospheric condition such as clouds and ashes soon after eruption time? � How to understand the characteristics of volcanic product detected for each eruption period? Clouds and ashes cover the volcano make optical sensor prevent to obtain surface condition.

Intensity Images of RADARSAT SAR for Mt. Merapi Before eruption After eruption Range Range Azimuth Azimuth Merapi 2002/05/14 Merapi 2006/05/17 The data acquired on May 14, 2002 as an initial condition of Mt. Merapi and on May 17, 2006 as data after the eruption occurred.

Merapi 2006/05/17 Range Dark portion on the RADARSAT Azimuth SAR data was represented as uniformity flowing material such pyroclatic flow s as settling by gravitational energy Incident wave www.indahnesia.com & Bronto, 2006 Smooth Rough

Topographic Abrupt Change Detection Before eruption Square root of subtraction powered image After eruption Changed volcanic product, 2002 to 2006 data, shows some new features clearly.

Square root of subtraction Subtraction image Ratio image powered image Mt. Merapi Fault www.indahnesia.com & Bronto, 2006 Geological map of the Yogyakarta sheet. (Rahardjo et al., 1995)

β o Image Ratio Image Pyroclastics Temporal arithmetical calculation and low level feature extraction were used to discriminate volcanic product distribution Lava Lava flows differ from pyroclatic flows based on different peak histogram from bi-level threshold images

SAR Pair Temporal Detection SAR data SAR pair history Ten SAR data which are divided into 6 pairs were used to obtain the characteristics of Mt. Merapi volcanic distribution

Result Result � Temporal detection Geometry of pyroclastic deposit � Low level feature extraction -Binarization -Region descriptor � Vectorizing � Geometric calculation -Area -Travel distance -Azimuth Azimuth Pair of SAR data Area Distance Pair Sensor (yyyy.mm.dd) (km 2 ) (km) Modeling S … W I 1996.04.06 1996.11.12 0.8 2.3 F(x)=0.92x-123.76 47.0 ° JERS-1 II 1996.04.06 1997.02.08 1.0 3.3 F(x)=0.76x-108.8 53.0 ° JERS-1 III 1998.01.26 1998.07.21 2.0 4.7 F(x)=0.44x-80.38 66.0 ° JERS-1 IV 1998.08.15 2000.11.08 3.3 4.4 F(x)=0.22x-64.23 78.0 ° RADARSAT-1 V 2001.02.12 2002.05.14 2.3 3.9 F(x)=0.16x-59.75 81.0 ° RADARSAT-1 VI 2002.05.14 2006.07.04 1.8 2.2 F(x)=0.15x-58.8 81.3 ° RADARSAT-1

Temporal Change of Pyroclastic Temporal Change of Pyroclastic Deposits of Mt. Merapi Deposits of Mt. Merapi Characteristics of pyroclastic deposits over ten years observation Pyroclastic flows change of Mt. Merapi

Conclusions Conclusions 1. Using SAR amplitude data extraction, some geological and topographical features are easier to be obtained. 2. In ten years observation of SAR data, there are three characteristics found for pyroclastic flows deposits; coverage area, travel distances and azimuth of the flows. 3. The coverage areas and travel distances of volcanic deposit of Mt. Merapi is scattered by time eruption. 4. However, the azimuth of pyroclastic flow deposits which has changed constantly to one tendency. The products rotated clockwise from the south to the west.