## 3 Datasets  
The basis of the developed change analyses for the detection of volcanic hazards is PlanetScope data. PlanetScope is a satellite constellation of over 150 CubeSats (Doves) (\(10\text{ cm}\times 10\text{ cm}\times 30\text{ cm}\)) capable of recording the entire Earth's landmass (approx. 1.49 \(\times\) 108 km\({}^{2}\)) on a daily basis [43; 44]. The constellation has been continuously recording data since June 2016 and has been extended by additional Dove generations in subsequent years. In total, three different generations exist, all of which have slightly different sensor systems (1 st generation: PS2, 2 nd generation: PS2.SD, 3 rd generation: PSB.SD). Depending on the generation, PlanetScope satellites are equipped with three (blue, wavelength \(\lambda\) = 455-515 nm; green \(\lambda\) = 500-590 nm; red \(\lambda\) = 590-670 nm) or four bands (additional near infrared (NIR) \(\lambda\) = 780-860 nm) [44]. PlanetScope has a geometric resolution of 3.7 m, which is resampled to 3 m within the provided data products [44]. Depending on the different Dove generations, the swath width thereby varies between 25-30 km \(\times\) 8-10 km [18; 44]. Furthermore, almost all satellites fly at an altitude of 475 km in a near-polar orbit with inclinations of 8\({}^{\circ}\) and 98\({}^{\circ}\)[43]. In addition to daily coverage of the entire Earth's landmass, overlap areas occur with successive Doves, which are recorded multiple times with a time offset of a few minutes and can thus be used to observe short-term, dynamic processes at the Earth's surface [45]. Complementary to the PlanetScope imagery, Sentinel-2 Multispectral Instrument (MSI) and Landsat-8 Operational Land Imager (OLI) data were included in the change analysis. First, these datasets were used to create multispectral false-color representations during eruption periods at the analyzed volcanoes. These were used for visual analysis and validation of the lava area derived from the PlanetScope. Second, thermal anomalies (so-called hotspot), detected by the Normalized Hotspot Indices (NHI) [46], were derived from the Sentinel-2 and Landsat-8 imagery during an eruption period and used as an input dataset for object-oriented lava flow mapping (Section 4.3). The Sentinel-2 satellites (2A and 2B) fly in a near-polar sun-synchronous orbit at an altitude of 786 km and have a temporal resolution of 5 days. The MSI sensor on board of the Sentinel-2 satellites has thirteen spectral bands in the wavelength range between visible light (VIS) (\(\lambda\) = 443 nm) and shortwave infrared (SWIR) (\(\lambda\) = 2190 nm) in three different geometric resolutions (10 m, 20 m, 60 m) [47]. Landsat-8 flies in a near-polar sun-synchronous orbit at an altitude of 705 km and has a repetition rate of 16 days. The OLI sensor has nine spectral bands with a geometric resolution of 15 m (panchromatic) or 30 m (VIS-SWIR) in the wavelength range from VIS (\(\lambda\) = 443 nm) to SWIR (\(\lambda\) = 2290 nm) [48]. In addition, Landsat-8 has the Thermal Infrared Sensor (TIRS), which acquires two bands in the thermal wavelength range (\(\lambda\) = 10.6-12.51 um) with a geometric resolution of 100 m [48]. For the generation of false-color representations for monitoring thermal anomalies (Section 6.1), Sentinel-2 and Landsat-8 data were obtained via Google Earth Engine (GEE) for the Karangetang I, Karangetang II, and Krakatau I eruption events. Furthermore, two additional Sentinel-2 L2A scenes were downloaded for eruption phase Karangetang II. These were used to test the application and functionality of the developed object-oriented change detection method (Section 4.3) with data having a lower geometric resolution than PlanetScope (Section 6.3). For this purpose, a pre- (9 May 2019) and post- (4 December 2020) eruption scene were selected. Due to the good geometric resolution and the availability of SWIR bands, Sentinel-2 and Landsat-8 are well suited for monitoring thermal activities at active volcanoes [15; 49].