IEEE Transactions on Pattern Analysis and Machine Intelligence

Digital terrain representation. Data Acquisition Methodology. Terrain Surface Modeling (Reconstruction). Algorithms for Triangular Irregular Network Formation. Interpolation Methods. Data Quality Control. Mathematical Models for DTM Accuracy.Multi-Scale Representation of Digital Elevation Models. DTM Data Management. Contouring from DTM. DTM-Based Terrain Analysis (DTM Interpretation). Visualization of DTM Surface. Applications. Integration with GIS. Index.

Digital Terrain Modeling: Principles and Methodology

https://hal-insu.archives-ouvertes.fr/insu-00723412/document

The 2010 explosive eruption of Java's Merapi volcano—A ‘100-year’ event

This paper provides a review of ground-based SAR (GBSAR) interferometry for deformation measurement. In the first part of the paper the fundamentals of this technique are provided. Then the main data processing and analysis stages needed to estimate deformations starting from the GBSAR observations are described. This section introduces the two types of GBSAR acquisition modes, i.e., continuous and discontinuous GBSAR, and reviews the different GBSAR processing and analysis methods published in the literature. This is followed by a discussion of the specific technical aspects of GBSAR deformation measurement. A section then summarizes the pros and cons of GBSAR for deformation monitoring. The last part of the paper includes two reviews: one concerning the GBSAR systems described in the literature, including non-strictly SAR systems and a second one addresses the main GBSAR applications.

A review of ground-based SAR interferometry for deformation measurement

Paroxysmal dome explosion during the Merapi 2010 eruption: Processes and facies relationships of associated high-energy pyroclastic density currents

Abstract One fundamental component of early warning systems for natural hazards is displacement monitoring. Spaceborne SAR Interferometry has proven to be a powerful remote sensing tool for this task. Lately new ground-based SAR instruments are available. Their application field is wide and they combine high resolution and accuracy with the classical benefits of remote sensing techniques. Here, the principles of the microwave interferometer IBIS are presented, as well as its advantages and disadvantages compared to common monitoring techniques. IBIS can be operated in two modes: IBIS-S is a microwave interferometer capable of high frequency displacement monitoring of buildings and structures (up to 200 Hz); IBIS-L is a ground-based SAR for long-term displacement monitoring of buildings and natural phenomena as landslides, glaciers, etc. Exemplary three applications are presented: the use of IBIS-S for dynamic monitoring of a chimney; the use of IBIS-L for displacement monitoring in an active quarry and the long-term operation of IBIS-L as part of a “Volcano Fast Response System” (VFRS) on an active volcano.

Monitoring of displacements with ground-based microwave interferometry: IBIS-S and IBIS-L

[1] Merapi is a high-risk andesitic volcano in Central Java, Indonesia. Very little information is known about the detailed regional density structure around Merapi and its neighbor volcano Merbabu. We compute a subsurface three-dimensional (3-D) model of anomalous density for the volcanoes Merapi and Merbabu in Central Java, Indonesia, by inversion of the gravity field. As input for the inversion methodology, gravity observations from 443 points, whose 3-D coordinates are determined by GPS, are used. The inversion algorithm is based on an explorative approach to fit a least squares condition, including a balancing factor between the minimization of the residuals and the anomalous mass. A mean density about 2242 kg/m3 for the region of Merapi and Merbabu has been computed by least squares adjustment. Results of the inversion show major low-density contrasts up to −242 kg/m3 and positive structures about +264 kg/m3, referred to the determined mean density. A density anomaly (relative high) with densities up to +264 kg/m3 is connecting the volcanoes in a 152° course from NW to SE and might be built of older basaltic lava. Low-density contrasts about −242 kg/m could be found in agreement with magnetotelluric and electromagnetic results. Generally, the identified high- and low-density bodies are in agreement with the results of other geophysical methods such as electromagnetic and magnetotelluric prospecting or geological formations and structures. A porosity about 21% is derived for the largest negative density bodies about −242 kg/m3. Furthermore, the density model gives some new information about the controversial origin of a hill formation near Merapi and is also used to discuss the possible existence of a shallow magma chamber, which is also a controversial subject. Generally, the density model serves as basic information for the interpretation of geodetic and geophysical observations and confirms existing results from magnetotellurics, electromagnetics, and seismic data interpretation.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2005GC000986

Modeling the density at Merapi volcano area, Indonesia, via the inverse gravimetric problem

https://hal.archives-ouvertes.fr/hal-00615321/document

Digital elevation model with the ground-based SAR IBIS-L as basis for volcanic deformation monitoring

. The accuracy of 4 Digital Elevation Models (SRTM30, GTOPO30, SRTM3 and local DEM produced from aerial photogrammetric images) for the volcanoes Merapi and Merbabu in Java, Indonesia is investigated by comparison with 443 GPS ground control points. The study confirms the high accuracy of SRTM3 and SRTM30, even if the a priori defined 90% confidence level of 16 m for the SRTM3 is not always achieved in this mountainous region. Accuracy of SRTM30, GTOPO30 and SRTM3 is mainly dependent on the altitude itself and the slopes' inclinations, whereas the photogrammetric DEM exhibits constant accuracy over a wide range of altitudes and slopes. For SRTM3 and SRTM30 a statistically significant correlation between heights and aspects of the slopes is also found. Accuracy of DEMs which are generated by interpolation on a finer grid does not change significantly. Smoothing of DEMs on a coarser grid, however, decreases accuracy. The decrease in accuracy is again dependent on altitude and slope inclination. The comparison of SRTM30 with GTOPO30 exhibits a significant improvement of SRTM30 data.

/pdf/validation-of-digital-elevation-models-around-merapi-volcano-1yyf3nrwri.pdf

Validation of Digital Elevation Models around Merapi Volcano, Java, Indonesia

Temporal gravity changes provide information about mass and/or density variations within and below the volcano edifice. Three active volcanoes have been under investigation; each of them related to a plate boundary: Mayon/Luzon/Philippines, Merapi/Java/Indonesia, and Galeras/Colombia. The observed gravity changes are smaller than previously expected but significant. For the three volcanoes under investigation, and within the observation period, mainly the increase of gravity is observed, ranging from 1,000 nm−2to 1,600 nms−2. Unexpectedly, the gravity increase is confined to a rather small area with radii of 5 to 8 km around the summit.

Carl Gerstenecker

Papers

Monitoring of displacements with ground-based microwave interferometry: IBIS-S and IBIS-L

Modeling the density at Merapi volcano area, Indonesia, via the inverse gravimetric problem

Digital elevation model with the ground-based SAR IBIS-L as basis for volcanic deformation monitoring

Validation of Digital Elevation Models around Merapi Volcano, Java, Indonesia

Gravity Changes and Internal Processes: Some Results Obtained from Observations at Three Volcanoes