The provinces of Bangkok, Samut Prakan, Samut Sakhon, and Nakhon Pathom in Thailand are experiencing subsidence caused by land subsidence, tectonic activity, and sea-level rise. INSAR result from 2015-2022 show that Bangkok and nearby provinces subsided up to 3 cm/yr in the past 20 years. GNSS results show absolute subsidence rates (below 20 m) up to 5 mm/yr in the past 25 years. According to satellite altimetry data, Bangkok is currently experiencing a sea-level rise of up to 5 mm per year in the Gulf of Thailand. Ground water pumping also play an important role on land subsidence. ... Read more

In August 2021 Askja caldera in Iceland started to show uplift after decades of subsidence. The uplift signal is centered at the northwestern edge of lake Ӧskjuvatn and an order of magnitude larger than the subsidence in the last decade. In September 2021 a geodesy campaign was carried out at Askja, including relative microgravity measurements acquired with the use of two Scintrex CG-5 instruments. Relative microgravity campaigns at Askja are not straightforward due to the long walking distances between sites, which makes a “double loop” procedure impossible. We revisit existing Scintrex relative microgravity data sets (2015 onward) and analyse data using the same joint weighted least squares inversion routine. We define recommendations for future relative microgravity campaigns at Askja which will be important to establish the cause of the ongoing uplift. The density of subsurface magma is only identifiable with microgravity data. Knowledge of the type of magma accumulating under Askja is vital to assess possible hazard implications. ... Read more

Using a combination of multi-directional SAR and TIR measurements, the Harmony Earth Explorer 10 mission candidate will provide high resolution simultaneous measurements of surface stress, surface currents SST and wave spectra over oceans, 3-D deformation vectors over solid Earth, and time-series of surface elevation changes over volcanic areas and land ice masses. This will serve a series of science objectives aimed at better understating multi-scale processed and feedbacks in the Earth System. ... Read more

This paper provides a compact overview of Harmony, an Earth Explorer 10 mission candidate dedicated to the observation of dynamic deformations of ice, solid earth and ocean surfaces. Harmony consists of two receive-only small Synthetic Aperture Radar (SAR) satellites using Sentinel-1 as illuminator, which will alternate close formation phases, dedicated to single-pass cross-track interferometry, with StereoSAR phases dedicated to the study of ocean surface motion and 3-D land surface deformations. In addition the payload includes a compact Thermal Infrared (TIR) camera. ... Read more

The Black Sea coast of the Great Caucasus has always been a region of high landslide risk due to widely spread clays and marls seasonally saturated by abundant rainfalls. In recent years landslide risk assessment has become vital because of strongly increased human-induced impact dealt with construction of the Sochi-2014 Olympic Games facilities which triggered landsliding. Thus, identification and monitoring of slowly moving landslides is of particular interest. Our investigations demonstrated efficiency of INSAR application to locate and monitor activity of slowly moving landslides there. We studied the landslide activity in the area of the Bolshoy Sochi (Big Sochi) using the StaMPS software. We incorporated radar images from the satellites with different wavelengths from ascending and descending orbits: 13 Envisat images (track 35D, descending orbit, 14.08.2003-09.02.2006), 12 Envisat images (track 35D, descending orbit, 2007.11.01-08.07.2010), 13 Envisat images (track 35D, descending orbit, 29.11.2010-23.03.2012), 11 Envisat images (track 85A, ascending orbit, 01.08.2004-01.02.2009), 17 ALOS images (track 588A, ascending orbit, 22.01.2007-17.09.2010), 17 TerraSAR-X images (track 54A, ascending orbit, 24.12.2011-13.09.2012).

We present results of processing of all these data sets for the Moldovka landslide which is a typical representative of slowly moving landslides on the Black Sea coast of the Northern Caucasus being of particular interest as it is situated nearby theSochi airport. The Moldovka landslide is an ancient landslide in the Chvizhepse folded area. Displacements of this landslide became visible and were fixed by ground methods after heavy rainfalls in winter-spring 2012. The boundaries of the Moldovka landslide were clearly determined applying the Stamps technique to the above mentioned data sets. Analyzing the time series it was found out that displacements of the landslide took place starting at least in 2004. Analyzing all the deformation maps and time series we determined the LOS displacement rates in 2004-2013 being about 20-30 mm/Y with several accelerations induced by rainfalls. Maximum estimates of displacement rates in the down the slope direction were revealed in the first months of 2012 being about 150 mm/Y .

For atmospheric corrections we used the TRAIN software which appeared to be the most effective for the TSX data. Using the TRAIN software improved the results of the processing of the TSX data - boundaries of the landslide on the deformation map became more clearly seen and several new slowly moving zones became visible. ... Read more

Torfajökull is the largest silicic volcanic centre in Iceland lying at the intersection of the rift zone (MidAtlantic Ridge) and the transform zone that connects to Reykjanes peninsula. It erupts infrequently,with only two eruptions in the last 1200 years, the latest of which was over 5 centuries ago. Yet, itsactive tectonic setting, persistent high and low frequency seismicity, deformation and geothermalactivity within its large caldera (18x12 km diameter) indicate the continued presence of a long-lasting magma chamber. Here we speculate on possible geometry, size and depth of the Torfajökullmagma chamber by using radar interferometry (InSAR) and seismic interferometry (SI).Using InSAR time series analysis we detect a surface subsidence pattern at rates of up to ~13 mm yr-1in the SW region of Torfajökull ́s caldera, on-going since at least 1993. The subsidence rate isconstant in time, and perhaps due to a cooling magma chamber. The data can be fit reasonably wellusing a model of a NE-SW oriented spheroidal body at ~5 km depth. As the deflating area correlatesspatially with the area of geothermal activity, deflation may also be the surface response due to anactive hydrothermal circulation.To gain more insight into the geometry of Torfajökull’s magmatic system and rock properties of thesubsurface, we apply ambient noise seismic interferometry (SI) by cross-correlation of ambient noise.With this technique we can detect velocity variations, which can correspond to the edges of dikes ormolten magma bodies. Our tomographic results give reliable results of velocity variations within adepth range of 2 km to 7.5 km. We find high velocity zones that we interpret as old dike intrusions.Low velocity anomalies (>5%), which usually indicate the presence of warmer material, are locatedon the southeast and southwest part of the volcano, outside the volcano caldera.Finally we compare both InSAR and SI results. The hypothesis of a magma chamber under thesubsidence area detected by InSAR does not seem to fit the tomographic results, as the expectededges of a magma body modelled by InSAR are not clearly identified by the SI results. If there is anestablished magma chamber within Torfajökull caldera this is likely to be bellow 7km depth. ... Read more