Three‐dimensional density modeling of the EGM2008 gravity field over the Mount Paekdu volcanic area

Abstract

[1] Here we use the global gravity field data set EGM2008 for 3-D crustal density modeling of the Mount Paekdu stratovolcano and surrounding area located on the border between North Korea and China. Curvature analysis and Euler deconvolution are used to assist interpretation, and the 3-D model is constrained by multiple geological and geophysical data sets. Mount Paekdu is characterized by a low Bouguer anomaly of À110 × 10 À5 m/s 2 , which is caused by the combined gravity effects of (1) a depth to the Moho of about 40 km, (2) a zone with lower P wave velocity and density than the surrounding, (3) low density volcanic rocks on the surface, and (4) the presence of a magma chamber that has not previously been identified. The modeled magma chamber has a mean thickness of 5 km and a density of about 2350 kg/m 3 and is located <10 km from the surface. Magma chambers are also modeled beneath Mount Wangtian and Mount Nampotae. However, the results of the 3-D density modeling do not confirm the existence of a previously proposed midcrustal low-velocity zone in the area 70 km to the north of Mount Paekdu. Since the Pliocene, volcanic activity in the Mount Paekdu region has migrated from the east coast of North Korea to the northwest, following the path of NW-SE trending faults.

Investigation of Potential Volcanic Risk from Mt. Baekdu by DInSAR Time Series Analysis and Atmospheric Correction

“…Baekdu and to validate the effectiveness of our DInSAR observations, we conducted model inversion incorporating the DInSAR observations for a specific time period. According to [5], the Earth Gravitational Model (EGM) 2008 [68] was applied which approximates a magma chamber along with several faults. Hence in this study we combined the Mogi [69] and Okada [70] models to simulate a comprehensive underground source causing surface deformation.…”

“…Both models were optimized using the Levenberg-Marquardt algorithm (LMA) which was implemented using Gauss-Newton iteration and loops in order to obtain a convergence of the gradient descent [75]. Initial model values for geometrical parameters are set to ranges published in previous studies [5]. For the Mogi model they include depth, projected planar location, and volume; for the Okada model they include, length, width, depth, degree of dip and rake, distance of strike and slip.…”

“…Since only a few StaMPS/MTI results showed clear surface deformation and produced the source parameters in reasonable ranges, In the first scenario, a Mogi-type magma chamber of spherical shape in an elastic half-space [70] and four faults lines inferred from [5] were introduced. In this scenario the central magma chamber contributes to surface unrest by volume or pressure changes interacting with the faults lines as shown by, e.g., Feuillet et al [79].…”

“…Baekdu. Recently, Choi et al [5] conducted a gravity anomaly analysis using the Earth Gravitation Model (EGM) dataset covering Mt. Baekdu, and attempted to model the magma source.…”

“…. The faults lines and the estimated magma chambers from the gravity model in [5] and epicenters of earthquakes [2] are also represented. The Sentinel-2 space-borne image taken in October, 2010 is shown in (c).…”