Chemical explosions are ground truth events that provide data, which, in turn, can enhance the understanding of wave propagation, damage assessment, and yield estimation. On 4 August 2020, Beirut, Lebanon was shocked by a catastrophic explosion, which caused devastating damage to the Mediterranean city. A second strong chemical explosion took place at the Xiangshui, China chemical plant on 21 March 2019. Both events generated shock waves that transitioned to infrasound waves, seismic waves, as well as hydroacoustic signals with accompanying T-phases in the case of the Beirut event. In this work, the seismo-acoustic signatures, yields, and associated damage of the two events are investigated. The differentiainterferometry synthetic aperture radar analysis quantified the surface damage and the estimated yield range, equivalent to 2,4,6-trinitrotoluene [C7H5(NO2)3] (TNT), through a “boom” relation of the peak overpressure was evaluated. Infrasound propagation modeling identified a strong duct in the stratosphere with the propagation to the west in the case of the Beirut-Port explosion. In the case of the Xiangshui explosion, the modeling supports the tropospheric propagation toward the Kochi University of Technology (KUT) sensor network in Japan. Although the Beirut yield (202–270 ± 100 tons) was slightly larger than the Xiangshui yield (201 ± 83.5 tons), the near-source damage areas are almost the same based on the distribution of damaged buildings surrounding the explosions.

Kochi Prefecture is located in an active zone of Japan that is frequently subjected to landslides due to heavy precipitation in typhoon seasons. Slow-moving landslides have been reported by both the local prefectural authorities and the National Government of Japan. We observed landslide movements in Otoyo Town by using ground- and satellite-based tools. Despite the high cost of establishing a borehole inclinometer survey to obtain accurate ground-based measurements, no previous InSAR study has been conducted in Otoyo Town, and the capacity for regional discrimination between active and inactive slow-moving landslides when using these tools remains unclear. We found that the horizontal velocity component was dominant at a rate of 21.4 mm/year across the whole of Otoyo Town. Satellite-based monitoring of ground-anchor efficiency may be possible in combination with ground-based inclinometer surveys. Three types of land cover are present in the study area—urban, field, and forests—and we selected a random forest (RF) model to extract low-coherence pixels by using optical and radar satellite sensors to identify important features and precisely remove pixels causing decorrelation. Long-term monitoring results from ground-based surveys, including inclinometer (boreholes) and anchor tension distribution data, were compared with the results of synthetic radar by using coherence-based small baseline subset (CB-SBAS) measurements. Generally, landslide occurrence was investigated across the whole of Otoyo Town, and we specifically evaluated the reliability of InSAR measurements in the Kawai landslide as a study site scale. The activity of the Kawai landslide channel was evaluated with borehole inclinometer displacement measurements (15.46 mm) and an anchor pressure survey (736 kN) from 2016 to 2019, as well as the steady state of the area (1.7 mm for the borehole inclinometer and 175 kN for the anchor pressure measurements), although a high cumulative precipitation of 3520 mm was reached during 2020 due to the ground anchor efficiency, which showed a consistent tendency with respect to the InSAR displacement measurements (14 mm during 2018 and 2019 and 0.7 mm during 2020). This comparison showed a consistent time-series displacement correlation, which was strengthened after introducing the RF mask into the analysis procedure, as the RF model correction reduced the standard deviation from the line-of-sight (LoS) average velocity estimation by 1.9 mm/year. Our research will help mitigate landslide impacts in Otoyo Town and its surroundings.

Land deformation due to natural and anthropogenic impacts considered to be one of the challenging environmental problems in the Aswan area located in the southern part of Egypt. Specifically, we applied multi-sensor analysis in order to record the slow rate of subsidence with a high spatial resolution of COSMO-SkyMed (X-band) and Sentinel-1 TOPSAR (C-band) scenes. We proposed multi-temporal DInSAR data analysis by means of ascending and descending orbit tracks during the recent time period of 2012-2017. The stacked DInSAR results reported the occurrence of land subsidence of active urban areas. A strong correlation between the ground truth data, ground leveling, and the estimated Line of Sight (LOS) displacement time series values are reached, assuming the ground deformation controlled by seasonal surface water loading, lithological units, and subsurface water activity. The detection of short-term displacement highlights the priority of groundwater management plans in the affected urban areas.

In the last few years, ALOS/PALSAR (L-band) (HH, HV, VH and VV) images have been widely used due toits ability to penetrate the surface in certain conditions for example of low moisture or dry friable sandysoil. Images from ALOS-1 sensor have been applied to delineate subsurface structures. Optical imagessuch as Landsat-7 ETM+ data are used to discriminate between scatterings from earth surface andsubsurface materials. Thus, Farafra desert is an optimal environment for L-band microwave penetration.Therefore, this research involves mapping and interpretation of lineaments, surface and subsurfacestructures. The interested four spots at Farafara sand sheets display many structures that not have beentraced in the Egyptian official geological maps. Speckle noise is found in radar images due to many reasons, for example, when an object stronglyreflected between itself and the spacecraft causing noise. Refined LEE Filter (RLF) is applied for specklenoise reduction; speckle noise near strong edges is not strongly filtered, leaving the center of the pixelunfiltered, so, this procedure is an essential step in processing of polarimetric data to improve theaccuracy of the data and enhance resolution. ALOS/PALSAR data are processed into circular polarizationfor providing the best viewing of morphological and subsurface lineaments. The ellipse shape governed bytwo axes; semi-major axis ‘a’ and semi-minor axis ‘b’. Orientation angle(ψ) is measured frompositive horizontal axis X counter clockwise direction, orientation angle range from 0° to 180°. Ellipticity(χ) is a shape parameter defined by the degree of oval shape, defined by χ=arctanb/a and can takevalues between -45° to +45°. As, the circular polarization yielded best outputs of subsurface structure indifferent trends, full polarimetric ALOS/PALSAR images (PLR) are transformed into circular polarization, bychanging both angles into orientation angle ψ=0° and elliptical angle χ=45°. Full polarimetric images arerepresented in Pauli RGB. Landsat-7 ETM+ data are freely uploaded with the same date and location ofALOS/PALSAR images. Bands 1, 2, 3, 4, 5 and 7 are merged together, then bands (R:2, G:4, B:7) arechanged to obtain best spatial resolution. Landsat-7 images have some gap areas, which is essentially befilled with Landsat-7 data acquired at the same time of the year by histogram matching technique to fillthe missed pixels of the interested target scenes according to Landsat 7. The obtained rose diagramshows two trends of dominant and secondary; the most dominant direction is North West (NW 330°),while the secondary trend is North (North 10°). This result is confirmed by the field survey. The dominantdirection of lineaments extracted from ALOS/PALSAR images is well fitted with the secondary direction ofthe geological structure in the study area. This work represents a stage of achievement in detecting buried lineaments covered by sand sheets byusing ALOS/PALSAR and Landsat-7 ETM+. Surface and subsurface