Over 12 years of continuous monitoring of Changbaishan volcano in the border region of China and North Korea by means of volcanic seismicity, ground deformation, and volcanic gas geochemistry yields new evidence for magmatic unrest of the volcano between 2002 and 2006. In this so‐called “active period,” the frequency of volcanic earthquakes increased by about 2 orders of magnitude compared to that of the background “inactive periods.” The active period was also accompanied by ground inflation, high values of CO2, He, H2, and high ratios of N2/O2 and 3He/4He in volcanic gases released from three hot springs near the caldera rim. The monitoring evidence implies pressurization of the magma chamber, possibly caused by incremental magma recharge. The ground deformation data from both GPS and precise leveling are modeled to suggest the corresponding deformation source is at 2–60 km depth beneath the volcano's summit, where earthquake swarms were detected in 2002 and 2003. Our findings suggest that the magma chamber beneath Changbaishan volcano has awakened and resumed activity after remaining dormant since AD 1903. There is an urgent need to keep close watch on this active and very hazardous volcano in northeast China.
Precise leveling data observed in the period of 1970-2014 around the Ordos block were collected and processed to estimate present-day crustal vertical movement. Vertical rates of 6 GPS sites were employed as a priori constraints to define the reference frame. The velocity field shows that the interior of the Ordos block moves upward at a rate of 3 mm/a as a stable block. With respect to the central Ordos, the grabens and rifts around the Ordos block are undergoing subsidence, while the northeastern and southwestern Ordos uplift at the average rates of 2 and 1 mm/a, respectively. To the southeastern margin of the Ordos block, the Weihe and southern Shanxi grabens are subsiding at the rates of 4-6 mm/ a. The subsidence of the Shanxi graben indicates that the graben is experiencing extensional movement on a long timescale. To the northwestern margin of the Ordos block, the Hetao and Yinchuan rifts are subsiding at the rates of 2-3 mm/a. A 2-D buried faulting model is used to infer the normal or reverse dip-slip rates. Our solution shows that most of the normal slip rates along the faults in the grabens and rifts are *2 mm/a.
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