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Limbah pangan terutama ampas tahu merupakan salah satu masalah yang perlu mendapat perlakuan serius di Indonesia karena menjadi penyebab berbagai macam masalah lingkungan. Upaya penanganan yang bisa dilakukan salah satunya adalah memanfaatkan limbah ampas tahu menjadi produk tepung. Uji organoleptik digunakan sebagai indikator untuk mengetahui kualitas tepung ampas tahu. Hasil uji organoleptik yang optimal dihasilkan saat dilakukan pengeringan selama 90 menit dengan hasil tidak berbau ampas dan tekstur halus dan tidak menggumpal.

Lombok Island is an active seismic area in Indonesia potentially hit by an earthquake due to located between two earthquake generators from the south and the North. Several large earthquakes rocked Lombok, an earthquake with a magnitude of 6.4 on July 29, 2018, and 7.0 on August 5, 2018. This study aims to determine the characteristics of the local site effect based on the dominant frequency value ( ), soil amplification ( ), sediment layer thickness (d), , dominant period (T 0 ), and seismic vulnerability index ( ) and to comprehend the soil class (site class) based on the thickness of the sediment layer (d), and in the North Lombok region. The data used is secondary data from microtremor signal recordings in North Lombok Regency in 2018. Data processing used Geopsy software, and microtremor data were analyzed using the HVSR method. From processing the HVSR data, the dominant frequency value about (0.8 - 18) Hz, amplification value (1.7 – 9.7), dominant period value (0.05 – 1.2) seconds, seismic vulnerability index value (0.4 – 71) , and the value of in the study area (20.05 – 287.04) m/s. Based on microtremor analysis, the local site effect indicates that alluvium rocks caused stronger earthquake vibrations and more damage. Whereas the Kalibabak and Lekopiko formations caused fewer earthquake vibrations and less wear. Based on the dominant period and , area study classify as Site Class IV class E and Site Class III class D Copyright © 2021 IPR . All rights reserved.

Penelitian pembuatan tepung ampas tahu bertujuan untuk mengurangi limbah pengolahan tahu sehingga menjadi bahan yang lebih berdaya guna Metode penelitian menggunakan Rancangan Acak Lengkap (RAL) yang terdiri 5 (lima) perlakuan 15, 30, 45, 60, 75, dan 90 menit dengan diulang sebanyak 3 (tiga) kali. Pengujian data penelitian meliputi uji organoleptik. Data hasil pengujian dianalisis menggunakan analasis sidik ragam atau ANOVA dan uji lanjut Duncan,s Multiple Range Test (DMRT). Hasil penelitian uji organoleptik warna menunjukkan berpengaruh nyata dengan P6 sebagai perlakuan ideal menghasilkan warna putih kekuningan. Hasil uji organoleptik bau berpengaruh nyata dan tepung yang dihasilkan tidak berbau dengan lama 90 menit proses pengeringan. Hasil uji organoleptik rasa berpengaruh nyata dan tepung yang dihasilkan memiliki rasa khas ampas tahu. Hasil uji organoleptik tekstur berpengaruh nyata dan tepung yang dihasilkan memiliki tekstur tidak menggumpal dan halus.

Located about 30 km North of the city of Yogyakarta on Java island, Merapi is considered one of the most dangerous dome building stratovolcanoes, as about 2 million people live less than 30 km away from the crater. Its recent eruptive activity consists in cyclic effusive growth of viscous lava domes, followed by partial or total destruction of domes. Dome destruction favors gravitational collapses (VEI 2) every 4-5 years, or bigger explosive eruptions (VEI 3-4) every 50-100 years resulting in pyroclastic density currents (PDCs) driven downhill at high velocities that are a major risk for surrounding population. Therefore, it is crucial to assess precisely the location, the shape, the thickness, and the volume of emplaced lava in order to prevent populations from sudden PDCs. The last major explosive eruption (VEI 3-4) occurred in November 2010, resulting in a horseshoe-shaped crater of 500 m wide and 250 m depth hosting a lava dome shaped like a plateau. Within the crater, a new dome appeared on 11 August 2018 and was partially destroyed as of late 2019. In this study, we take advantage of 2 high resolution remote-sensing datasets, Pléiades (optical acquisitions in tri-stereo mode, 1 m resolution) and TanDEM-X (radar acquisitions in StripMap mode, 2 m resolution), to produce 19 Digital Elevation Models (DEMs) between July 2018 and December 2019. We calculate the difference in elevation between each DEM and a reference DEM derived from Pléiades images acquired in 2013 in order to track the evolution of the dome in the crater between 2018 and 2019. Uncertainties are quantified for each dataset. We show that the DEMs derived from Pléiades (optical) and TanDEM-X (radar) data are consistent with each other and provide good spatio-temporal constraints on the evolution of the dome. Furthermore, the remote-sensing estimate of lava volume is consistent with local drone measurements carried on by BPPTKG at the time of dome growth. The time period covered by the TanDEM-X data is larger than that covered by the Pléiades acquisitions, allowing coverage of the growth and destruction of the dome. However, the Pléiades data allow us to evidence an accumulation zone below the crater that is not well imaged by TanDEM-X. We show the dome reached 40 meters (+-5 m) high and 0.5 Mm3 (+- 0.1Mm3 ) between August 2018 and February 2019, corresponding to an effusion rate of 3000 m3/day. Its shape was initially radial,then extended asymmetrically to the northwest and southeast from October 2018. From February 2019 onwards, the dome elevation remained constant, but lava was continuously emitted, as evidenced by TanDEM-X amplitude maps. Lava supply was balanced by destabilization southwards downhill in an accumulation zone of 400 meters long and 15 meters (+-5m) high maximum. In late 2019, several minor explosions partially destroyed the center of the dome. This study highlights the strong potential of the combination of TanDEM-X and Pléiades DEMs to quantitatively monitor domes at andesitic stratovolcanoes.

A significant increase in the number of volcano-tectonic (VT) and VB earthquakes preceded the 2007 and 2014 eruptions of Kelud volcano, Indonesia. The background seismicity rates at the volcano is generally

Bali Island is one of the main tourist destinations in Indonesia. However, Bali Island is also prone to earthquakes, as evidenced by several historical destructive earthquakes, especially in the eastern part of Bali. A probabilistic seismic hazard modeling is undertaken to analyse the earthquake hazard, as well as studying the contribution of local geological conditions to earthquake ground motion. We use seismic waveforms retrieved from 23 temporary seismic stations across the eastern part of Bali Island from December 2018 to June 2019 and 5 permanent seismic stations around Mount Agung and Batur. The recording data were processed using the Horizontal to Vertical Spectral Ratio (HVSR) method. Our preliminary result shows local geological conditions for each station, represented by the value of the average shear-wave velocity on rocks to a depth of 30 meters (Vs30) and the total thickness of sediments above the bedrock (basin depth). These initial results will then be developed as site parameter input for probabilistic seismic hazard analysis in the eastern part of Bali.

DOI: 10.17014/ijog.7.3.241-252 To find out the long term data of Sinabung magma discharge rate and how long a series of eruption will be ended, time series of the volume of magma discharge is required. The dominant eruption product is pyroclastic flow that begins with the growth of the lava dome, so it is important to determine the volume of the lava dome over time. The method of determining the volume of magma issued is carried out by using hotspot data to resolve the problem of prevented visual observations and ground measurements. The heat and volume flux data expressed within a long period for a better view of variations in the Sinabung volcanic activity are based on thermal satellite data. Related lava dome volume and seismic data are also displayed to be compared with the heat and volume flux data. The numbers of thermally anomalous pixels and sum of radiance for all detected pixels at Sinabung during an overpass in the period of 2014 to 2018 have a downward trend. The discharge rates in the period of January 2014 to April 2015, Mei 2015 to March 2016, April 2016 to March 2017, and June 2017 to February 2018 are 0.86 m3/sec, 0.59 m3/sec, 0.36 m3/sec, and 0.25 m3/sec, respectively. Assuming no new intrusion or deformation rate changes, the lava discharge will be in the lowest rate in the early 2020s.

Located about 30 km north of the city of Yogyakarta, Merapi is considered as one of the most dangerous volcano of Indonesia with 3000 to 5000 fatalities since 1672 and about two million people living at less than 30 km from the crater. The recent eruptive history of Merapi is characterized by two eruptive styles: 1) recurrent effusive growth of viscous lava domes, with gravitational collapses producing pyroclastic flows known as « Merapi-type nuées ardentes » (VEI 2); 2) more exceptional explosive eruptions of relatively large size (VEI 3-4), associated with column collapse pyroclastic flows reaching distances larger than 15 km from the summit. The eruptive periodicity is 4 to 5 years for the effusive events and 50 to 100 years for the explosive ones. The last explosive events (VEI 3-4) occurred in November 2010 and opened a 500m wide and 250m deep crater. After the 2010 eruption, the activity has been reduced. We used TerraSAR-X data to characterize eruptive deposits emplaced during the 2010 event as well as sudden destabilization of crater walls. The activity increased significantly during the spring of 2018 when several phreatic eruptions were recorded with ash emission reaching an elevation of more than 5 kilometers. The 11th of August 2018 a new dome was observed inside the summit crater, thus marking the start of a new phase of effusive activity. It is essential to be able to quantitatively follow the temporal evolution of the dome shape and volume through time as its potential destabilisation would produce pyroclastic flow on the volcano flank. A time series of five tri-stereo Pleiades optical images, acquired between February and September 2019, is used to produce High Resolution DEMs of Merapi summit area with a spatial resolution of 3 m and a vertical precision of 1 m. By using a DEM derived from Pleiades stereo images acquired in April 2013 as a reference, the dome volume evolution through time is estimated. We show that the dome had already reached a volume around 0.5 Mm3 (+- 0.02Mm3) end of February 2019 corresponding to a mean effusive rate of 3000 m3/day during 6 months and that its size remained constant after February 2019. These results are consistent with volume estimations derived from drone measurements. However DEMs derived from Pleiades images enable to monitor a larger area and reveal accumulation of eruptive deposits due to dome destabilization a few hundreds of meters below the dome. The magma effusive rate thus remained significant but was reduced to 250 m3/day from February to September 2019.

This research is aim at determining the effect of styles of leadership, organization climate, and motivation of working to head of state of primary school in Central Jakarta work productivity. The method used was survey with a causal study by involving 125 respondents. There were four instruments which measured styles of leadership, organization climate, l motivation of working, and work productivity. Data has been analyzed by path-analyses. Research results revealed that: (1) there is positive and significant effect of styles of leadership to work productivity, (2) there is positive and significant effect of organization climate to work productivity, (3) there is positive and significant effect of motivation of working to work productivity, (4) there is positive and significant effect of styles of leadership to motivation of working, (5) there is positive and significant effect of organization climate to motivation of working. Therefore, it could be concluded that if head of state of primary school work productivity would be improved, then the effect of styles of leadership, organization climate, and motivation of working should be taken into consideration.

We compare identification, delineation and recording of freshly erupted deposits around active volcanoes from very high resolution optical images with that done by traditional geologic mapping. Object-oriented classification (OOC) and normalized difference spectral indices of vegetation, moisture and soil redness (NDVI, NDWI and NDRSI) have been applied to sub-metric GeoEye-1 and Pleiades images to identify and map pyroclastic and lahar deposits and trace their spatio-temporal evolution over two years, following the 2010 eruption of Merapi Volcano, Indonesia. We could identify several categories of pyroclastic depositional areas, and also map the damaged forest and destroyed cultivated terraces and settlements in the Gendol and Opak River basins on the south flank of the volcano. More than 75% of erupted deposits were delineated semi-automatically unlike the ground geological map based on photo-interpretation of the 2010 GeoEye image and field observations. A temporal image analysis, using bivariate scatter diagrams of the three spectral indices between 2010 and 2012 and a combination of NDWI and NDVI, separated areas affected by surges from unscathed vegetation. Use of NDRSI and NDWI allowed us to differentiate overbank Pyroclastic Density Current deposits from wet lahar deposits. NDRSI values close to 0 refer to scoria-rich pyroclastic deposits. About 40% of the devastated upper catchment was recolonized by vegetation between 2010 and 2012. The recovery also took place in the forested valley margins affected by ash-cloud surges. The morphometric analysis of the initial drainage network, digitized from the 2011–2012 images, demonstrated (1) the resurfacing of pristine 2010 PDC deposits by runoff and (2) incision or remobilization by lahars. It took two years following the eruption in the rugged upper catchment devastated by high-energy surges to fully develop the hydrographic network. It is, however, still rudimentary on gently sloping fans created by overbank PDC deposits in the middle valley, thus suggesting the importance of slope gradient, grain size, permeability and thickness of deposits. As much as 35% of the 2010 PDC deposits, emplaced in the vicinity of the river channels, were remobilized by lahars over the two post-eruption rainy seasons and also by constant mining activities. Studies on the erosion of the pyroclastic deposits after 2012 need to concentrate on the upper reach of the catchment on the south flank.

The 26 October-23 November 2010, eruption is Merapi's largest event (VEI 4) over the past 140 years. We tracked and identified the 2010 Merapi's PDC deposits in the most impacted catchment (South) using high-resolution optical (from GeoEye and SPOT-5 satellites as well as low altitude photograph) imagery. We show that high-resolution imagery enables mapping with unprecedented detail the effects of the 2010 eruption in the summit area and across the most devastated catchment on Merapi. We investigated the relationships between the morphology of the river channel, and the apparent behavior of the PDCs and lahars, as deduced from over-banking processes. The 2010 pyroclastic deposits cover an area of ∼27 km2 in the Gendol-Opak catchment, i.e. 35% of the total deposit area. We analyze how unconfined PDCs with over-bank and veneer facies, as well as two types of surges have mantled widespread areas on both sides of the Gendol valley which contain the confined PDC deposits. Geometric and geomorphic characteristics that allow over bank and veneer deposits beyond the main valley are: limited cross-sectional areas under 1500 m2 and the decreasing longitudinal rate of channel confinement. Subsequent lahars six months after the eruption have devastated several villages along the Gendol River 20km from the summit on the ring plain. Small areas down-valley was affected by over-bank lahars once pyroclastic deposits were remobilized 3.8km farther than the PDC front. The over-bank and avulsed lahars can be attributed to the limited capacity (200-250 m2) of river channels and meandering river (sinuosity index of 1.25) across the lowest-angle (

Di era modern seperti saat ini, sepeda motor sudah menjadi kebutuhan pokok untuk keperluan transportasi bagi hampir semua kalangan. Selain karena harganya yang terjangkau, penggunaan dan perawatannya yang mudah menjadi alasan mengapa banyak orang yang menggunakannya. Tetapi bersamaan dengan itu, tindak kriminal pencurian sepeda motor pun semakin meningkat. Atas latar belakang itulah maka dirancang sebuah alat pengaman tambahan pada penelitian ini. Alat yang dibuat menggunakan 3 (tiga) buah sistem keamanan, yaitu RFID scanner, RF modul communication, dan GPS function. RFID scanner berfungsi sebagai kunci tambahan, di mana selain kartu (tag) yang didaftarkan tidak ada kartu lain yang bisa digunakan untuk menyalakan relay. RF module communication berfungsi agar apabila pengemudi dan sepeda motor terpisah sejauh n meter, maka mesin sepeda motor akan mati secara otomatis. GPS berfungsi untuk memonitor / melacak di mana lokasi sepeda motor berada. Hasil yang didapatkan pada perancangan alat ini adalah RFID scanner dapat men scan kartu pada jarak 0 – 4 cm dan pada sudut 0 - 60° & 120 - 180°. RF modul dapat berkomunikasi pada jarak 0 – 20 meter tanpa penghalang, dan GPS modul dapat merespon SMS dari pengguna dalam waktu 27 detik dengan tingkat akurasi 10 meter.

Lactobacillus casei WSP-derived an aspartic protease was sequentially purified by using chromatography gel filtration sephadex G-50. It resulted in a 22.81-fold increase of specific activity (51.5 U/mg) with a final yield of 1.9%. The estimated molecular weight of the purified enzyme was 37 kDa and showed gelatinolytic activity in zymogram assay. The enzyme exhibited optimum activity at 40ºC and pH 6 with casein as the substrate. Enzyme activity was significantly inhibited by pepstatin A (0.5 mM and 1 mM), confirming that this enzyme is a group of aspartic proteases, while other inhibitors such as EDTA, PMSF and iodoacetic acid showed no inhibition effect on the activity of enzyme. The addition of metal ion to the enzyme decreased enzyme activity, indicating the proteolytic enzyme was metal ion- dependent. Denaturant such as DDT tended to increase caseinolytic activity. Furthermore, this enzyme was capable of generating the new peptides from skimmed milk with the size 8 kDa, 10 kDa and 15 kDa. These peptides have potential as antibacterial and antioxidant agents.

Data citra satelit sering digunakan untuk klasifikasi lahan, akan tetapi masih terdapat kelemahan terutama mengenai ukuran resolusi spasialnya karena daerahnya yang relatif sangat luas dan terkendala dengan awan/kabut. Dengan menggunakan data foto udara kajian klasifikasi tutupan lahan tersebut dapat diklasifikasi secara detail karena resolusinya lebih tinggi. Dalam optimalisasi pemanfaatan data UAV ini, diperlukan proses klasifikasi berdasarkan obyek sebab data dalam penginderaan jauh resolusi tinggi obyek terlihat cukup jelas dan jika menggunakan klasifikasi berdasarkan piksel maka hasil klasifikasi menjadi kurang akurat terutama saat proses ekstraksi obyek tertentu. Dalam kegiatan penelitian ini bertujuan untuk mengetahui hasil klasifikasi OBIA dalam menganalisis tutupan lahan di Desa Pagak, Kabupaten Purworejo Jawa Tengah. Dari hasil tutupan lahan menggunakan OBIA terdapat tujuh kelas klasifikasi tutupan lahan yaitu sawah, ladang, tanaman campuran, permukiman, rawa, tambak dan jalan. Uji akurasi hasil klasifikasi berbasis obyek untuk tutupan lahan dari data foto udara menunjukan hasil yang akurat yakni 90%.Kata kunci: OBIA, foto udara, tutupan lahan

This paper presents a method for analyzing Synthetic Aperture Radar (SAR) and polarimetric SAR (PolSAR) image time series based on change detection matrices (CDM) containing information on changed and unchanged pixels. These matrices are constructed for each spatial position over the time series by implementing similarity cross tests. The proposed matrix is then exploited for adaptive temporal filtering, analysis of change dynamics and multitemporal change detection. The proposed approach is illustrated on the three following data sets: 25 ascending TerraSAR-X images and 7 descending RADARSAT 2 full polarization images over Chamonix-MontBlanc, France, where the seasonal evolution of glaciers and mountains can be observed, and a time series of 11 ascending ALOS-PALSAR dual polarization images over Merapi volcano, Indonesia during a period including the 2010 eruption. Published by Elsevier B.V. on behalf of International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS).

International audience; L-band ALOS-PALSAR images acquired before, during and after the 2010 Merapi eruption have been used to classify and map the pyroclastic deposits emplaced during this VEI-4 event. We characterize the deposits using direct-polarized and cross-polarized L-band SAR data and by combining the information of amplitude evolution with temporal decorrelation. Changes in amplitude of the radar signal enable us to map the pyroclastic density currents (PDCs) and tephra-fall deposits. Radar amplitudes in direct (HH) and cross (HV) polarizations decrease where the valley-confined and overbank block-and-ash flow (BAF) deposits (D1) are emplaced. Rainfall- and runoff-reworked PDC deposits (D2) are characterized by an increase in ground backscattering for HH polarization and a decrease for HV polarization. Ground backscattering transiently increases in both polarizations after pyroclastic surge (D3) and tephra fall (D4) deposition. We use a supervised classification method based on maximum likelihood to map the deposits D1–D4. The temporal decorrelation of the radar signal and the amplitude evolution improve the quality of classification results. Classification derived from ALOS-PALSAR images using the maximum likelihood classification provides a result with 70% classification accuracy for deposits overall. The estimated areas of valley-confined and overbank PDC deposits (either primary or reworked by rainfall and runoff) are consistent with the areas measured by other studies, while the large discrepancy in area estimated for pyroclastic-surge deposits can be partly explained by the strong erosion due to intense rainfall that removed a large part of these thin deposits.

Pengukuran mikrotremor di Kota Banda Aceh telah dilakukan untuk mengetahui periode dominan dan nilai faktoramplifikasi guncangan gempa bumi. Pengukuran dilakukan pada 92 titik ukur memakai seismometer 3 komponenmodel Lennartz LE-3D berperiode natural 5 detik dan perekam digital model SARA SL-06 24 bit. Peta mikrotremorKota Banda Aceh terdiri atas periode dominan dan H/V amplifikasi. Periode dominan Kota Banda Aceh menunjukkanterdapat tiga kelas situs tanah yaitu : kelas situs C (tanah keras) dengan nilai periode dominan 0,2 detik < T ≤ 0,4detik, kelas D (tanah kaku) dengan nilai periode dominan antara 0,4 detik hingga 0,6 detik, dan kelas E (tanah lunak)dengan nilai periode dominan di atas 0,6 detik. Kelas situs D dan E menyebar hampir ke semua kecamatan sementarakelas situs C hanya terdapat di Kutaraja. Nilai H/V amplifikasi Kota Banda Aceh bervariasi antara 1,98 hingga 5,88.Kata kunci : periode dominan, ampilifikasi, kelas situs tanah.ABSTRACTMicrotremor measurement was conducted to obtain dominant period and site amplification factor of Banda AcehCity. The measurements were carried out in 92 sites in the city using 3-component-seismometer Lennartz LE-3D withnatural period 5 s and data logger model SARA SL-06 24 bit. The microtremor map of Banda Aceh City consists ofdominant period and H/V amplification factor maps. The dominant period of Banda Aceh City consisting of three siteclasses are C (hard soil) with dominant period 0.2 s < T ≤ 0.4 s, D (stiff soil) with dominant period between 0.4 sto 0.6 s, and E (soft soil) with dominant period greater than 0.6 s. Site class D and E areas stretch out almost in allsubdistricts, while C class is only in Kutaraja. The H/V amplification value of Banda Aceh city varies between 1.98and 5.88.Keywords : dominant period, amplification, site class.

Dans ce travail nous étudions le flanc sud du volcan Merapi (Indonésie) dévasté par la grande éruption de 2010 (IEV 4). Nous poursuivons trois objectifs : (1) Identifier les dépôts pyroclastiques et de lahars grâce à la classification «orientée-objet» appliquée à trois images GeoEye-1 (1,64 m ; 15/10/2010 et 29/07/2011) et Pléiades (0,5 m ; 29/10/2012). Ces dépôts pyroclastiques comprennent les écoulements denses canalisés, ceux qui ont débordé des vallées et les déferlantes diluées à l'amont du bassin et sur les marges des vallées. (2) Suivre l'évolution temporelle de ces dépôts grâce aux indices spectraux calculés pour chaque image. Nous avons appliqué la classification orientée-objet aux indices spectraux, NDWI, NDVI et NDRSI (Indice Normalisée du Sol Rouge). Les résultats ont permis d'identifier 15 classes de dépôts pyroclastiques, de lahars et les zones affectés dans la vallée de Gendol-Opak ( Ì´80 km²), qui représentent 75% de classes obtenues par photo-interprétation de l'image et appuyées par des observations de terrain. Les indices NDWI et NDVI ont mis en évidence les zones affectées par les déferlantes (NDWI 0,3 et NDWI

International audience; Erosion processes on active volcanoes in humid climates result in some of the highest sediment yields on Earth. Episodic sediment yields after large eruptions have been evaluated, but not the long-term and continuous patterns on persistently active volcanoes. We have used high-spatial resolution satellite imagery and DEMs/DSMs along with field-based geologic mapping to assess accurately sediment budgets for the active Semeru Volcano in Java, Indonesia. Patterns of aggradation and degradation on Semeru differ from that of other active volcanoes because (1) both episodic pyroclastic density currents (PDC) and continuous supplies of tephra generate pulses of sediment, (2) sediment is transferred via cycles of aggradation and degradation that continue for >15 years in river channels after each PDC-producing eruption, and (3) rain-triggered lahars remove much greater material than fluvial transport during long, intense rainfall events. The geomorphic response of two of Semeru’s rivers to volcanic sediment migration indicates that (1) each river experiences alternating aggradation and degradation cycles following PDC-producing eruptions and (2) spatial patterns of sediment transfer are governed by geomorphic characteristics of the river reaches. Usually high degradation in the steep source reach is followed by a long bypassing middle reach. Aggradation predominates in the depositional reaches further down valley on the ring plain. Average sediment yields (103–105 t/km2/year) at persistently active volcanoes are two to three orders of magnitude lower than sediment yields after large and infrequent eruptions, but the continuous and steady sediment transfer in rivers removes more sediment on a mid-term (10 years) to long-term (30 years) basis. In contrast to the trend observed on composite cones after large and infrequent eruptions, decay of sediment yields is not exponential and river channels do not fully recover at steadily active volcanoes as episodic inputs from BAF eruptions, superimposed on the background remobilization of daily tephra, have a greater cumulative effect.

International audience; The present work explores the object-oriented classification (OOC) of high-spatial resolution (HSR) satellite panchromatic imagery for mapping the geology of the persistently active Semeru volcano and its ring plain, east Java, Indonesia. A panchromatic SPOT5 image and a digital elevation model (DEM) have been used to identify geologic units, structures, landforms and deposits. The panchromatic image was georeferenced and enhanced using histogram equalization. The enhanced image was segmented into polygons using the EnviFx (©Exelis) Software. The polygons were delineated and classified on the basis of spectral (panchromatic hues and textures), topographic (slope, elevation) information and geologic/geomorphic processes. The validity of classification was evaluated by interpreting Google Earth images, aerial photographs and limited field observations. The classification consists of three hierarchical levels across the volcanic area of about 745 km2. The first operational spatial level includes seven large volcano domains based on the spectral content of the volcanic, tectonic and lithological structures, and principal catchments. The second operational level, based on contextual relationships (topography, drainage network, vegetation cover type, stratigraphy and slope dynamics), encompasses 20 geological units that range between 30 and 80 km2 in area. Among the units, the third operational level distinguishes as many as 47 geomorphological sub-units (0.25–25 km2) according to slope gradient, deposit type, mass-wasting process and weathering. The resulting map provides a detailed pattern of geologic and geomorphic features unlike previous geologic maps that identified only 11 stratigraphic units. We show that the high-spatial resolution panchromatic SPOT5 scene can help to safely map the geology and landforms of persistently active volcanoes such as Semeru. We have applied the OOC technique on one HSR GeoEye panchromatic image to map another active volcano, Merapi in Central Java, after considerable geomorphic changes due to the large eruption in 2010.

The paper illustrates the application of high-spatial resolution satellite images in interpreting volcanic structures and eruption impacts in the Tengger–Semeru massif in east Java, Indonesia. We use high-spatial resolution images (IKONOS and SPOT 5) and aerial photos in order to analyze the structures of Semeru volcano and map the deposits. Geological and tectonic mapping is based on two DEMs and on the interpretation of aerial photos and four SPOT and IKONOS optical satellite images acquired between 1996 and 2002. We also compared two thermal Surface Kinetic Temperature ASTER images before and after the 2002–2003 eruption in order to delineate and evaluate the impacts of the pyroclastic density currents. Semeru's principal structural features are probably due to the tectonic setting of the volcano. A structural map of the Tengger–Semeru massif shows four groups of faults orientated N40, N160, N75, and N105 to N140. Conspicuous structures, such as the SE-trending horseshoe-shaped scar on Semeru's summit cone, coincide with the N160-trending faults. The direction of minor scars on the east flank parallels the first and second groups of faults. The Semeru composite cone hosts the currently active Jonggring-Seloko vent. This is located on, and buttressed against, the Mahameru edifice at the head of a large scar that may reflect a failure plane at shallow depth. Dipping 35° towards the SE, this failure plane may correspond to a weak basal layer of weathered volcaniclastic rocks of Tertiary age. We suggest that the deformation pattern of Semeru and its large scar may be induced by flank spreading over the weak basal layer of the volcano. It is therefore necessary to consider the potential for flank and summit collapse in the future. The last major eruption took place in December 2002–January 2003, and involved emplacement of block-and-ash flows. We have used the 2003 ASTER Surface Kinetic Temperature image to map the 2002–2003 pyroclastic density current deposits. We have also compared two 10 m-pixel images acquired before and after the event to describe the extent and impact of an estimated volume of 5.45 × 106 m3 of block-and-ash flow deposits. An ash-rich pyroclastic surge escaped from one of the valley-confined block-and ash flows at 5 to 8 km distance from the crater and swept across the forest and tilled land on the SW side of the Bang River Valley. Downvalley, the temperature of the pyroclastic surge decreased and a mud-rich deposit coated the banks of the Bang River Valley. Thus, hazard mitigation at Semeru should combine: (1) continuous monitoring of the eruptive activity through an early-warning system, and (2) continuous remote sensing of the morphological changes in the drainage system due to the impact of frequent pyroclastic density currents and lahars.

DOI: 10.17014/ijog.v5i4.106Rinjani is the second highest volcano in Indonesia with an elevation of 3726 m above sea level. The steep and highest cone of Rinjani consists mainly of loose pyroclastic ejecta and contains a crater with a few solfataras. The West of this cone is Segara Anak caldera. The western side of the caldera is occupied by a 230 m deep lake, covering an area of 11 km² and its volume was (before the 2009 eruption) estimated 1.02 km3. This is probably the largest hot volcanic lake in the world.The lake water is neutral (pH: 7-8) and its chemistry dominated by chlorides and sulfates with a relatively high TDS (Total Dissolved Solids: 2640 mg/l). This unusual TDS as well as the lake surface temperatures (20 - 22°C) well above ambient temperatures (14 - 15°C) for this altitude, reflect a strong input of hydrothermal fluids. Numerous hot springs are located along the shore at the foot of Barujari volcanic cone. Bathymetric profiles show also several areas with columns of gas bubbles escaping from the lake floor indicating a significant discharge of CO gas into the lake. The mass and energy balance model of Rinjani Crater Lake produce total heat lost value on the average of 1700 MW. Most of the heating periods of the lake occurred when the heat released by the surface of the lake to the atmosphere was lower than the heat supplied from the hydrothermal system. Peaks of heat losses correspond to period of strong winds. Crater lake monitoring can provide a basic information about deep magmatic activity and surface processes that occur in the volcano. The monitoring also contributes to predict the next eruption in order to improve mitigation of volcanic eruption. Precursory signals of the May 2009 eruption can be seen from significant changes in the temperature and chemistry of some of the hot springs, the increase of Fe concentrations in spring #54, chemical plume of low pH and dissolved oxygen, acidification of Segara Anak Lake, and increasing of lake surface temperatures. The new lava flow from May - August 2009 eruption covers an area of 650,000 m2. The shoreline was significantly modified by the entry of lava into Segara Anak Lake. The area of the lake is reduced by 460,000 m2.