## 1 Introduction  
Antarctic glaciers flow from the inland to the shore, forming an ice shelf or glacier tongue, and are eventually discharged into the ocean. As the motion of the glacier is closely related to the seaward ice flux, ice flow velocity is an important indicator of global climate change and sea level rise [1, 2, 3]. The flow velocity of a glacier changes due to mass balance variations caused by snowfall accumulation or sublimation on the surface of the glacier, changes in physical properties occurring inside and at the bed of the glacier, and basal sliding [4, 5, 6]. Apart from the surface mass balance, a number of studies have been conducted on the observation of glacial flow rates due to the action of the ice bed influenced by the basal water. The presence of melt water at the ice bed is an important factor in the change in ice velocity because it causes lubrication, reducing friction between ice and the bedrock, and accelerating the flow velocity of the ice [6; 7; 8]. The melt water generated on the ice bottom moves along the bedrock topography to form a water channel, and is stored in the hollow to form a subglacial lake. Subglacial lakes and water channels also affect the behavior of the glacier flow [9; 10; 11]. Lubrication occurs at the boundary between ice and the bedrock to accelerate the flow velocity of the glacier by reducing the frictional force. The sediments saturated with water also reduces the basal shear stress to easily cause basal sliding to accelerate the flow velocity of the glacier [12]. Satellite Synthetic Aperture Radar (SAR) is a very effective instrument in Antarctic glacial research because it can provide high-quality images regardless of the sun altitudes and weather conditions. Differential interferometric SAR (DInSAR) can be applied to measure the displacement of the glacier with centimeter accuracy. [PERSON] and [PERSON] [13; 14] calculated the precise flow velocity and strain rates of Campbell Glacier Tongue, a seaward extension of the Campbell Glacier in East Antarctica, through the DInSAR technique with tidal phase correction. The DInSAR phase of inland glacier can include vertical displacement due to the surface elevation change or the activity of subglacial lakes as well as horizontal ice flow. [PERSON] et al. [15] used DInSAR to observe the changes in the surface elevation of the West Antarctic Ice Sheet due to the movement of water level of subglacial lakes. In the study conducted by [PERSON] et al. [16], the displacement of Greenland Ice Sheet observed from DInSAR was interpreted as the depression of glacier surface due to the drainage of the subglacial lakes in the radar line-of-sight (LOS) direction. Double-differential interferometric SAR (DDInSAR) removes the constant displacement at two different times and shows only the temporally variable displacement. The DDInSAR technique has been mainly used to study the deformation of ice shelves and glacier tongues to detect the vertical displacement caused by tide by removing horizontal ice flow from the DInSAR signals and thus to define grounding line and hinge zone of glaciers [17; 18; 19; 20]. As the displacement derived from the DDInSAR technique is the remainder of removing constant displacement from the DInSAR at two different times, it is possible to observe the velocity anomaly by applying the technique to the inland glaciers. Glacier velocity anomalies can affect not only changes in seaward ice flux, but also the formation of surface crevasses. Therefore, it is very important to detect the velocity anomalies of glacier and analyze their occurrence mechanism. It is difficult to identify the mechanism of the velocity anomalies with the DDInSAR technique alone. The velocity anomalies can be influenced by the bedrock topography and the presence of basal water. In order to clearly explain the mechanism of velocity anomalies, geophysical exploration data on the glacier should be acquired and analyzed.