Surface deformation of 0206 Hualien earthquake revealed by the integrated network of RTK GPS

Abstract

At 23:50 (local time, UTC+8) on 6 February 2018, a shallow earthquake of magnitude 6.2 on Richter scale occurred at the coastal area of Hualien, inducing significant fault activities on the Milun and Lingding Faults, and caused ruptured surface, damaged infrastructures and collapsed buildings. To understand the influence of the earthquake, this paper investigates the affected areas after the earthquake by using the network RTK to measure more than one hundred benchmarks set up by various government agencies for surface deformation measurement. The results of the investigation showed that the Milun Terrace moved along the Milun Fault in a left lateral motion with a reverse component in the northern part of the terrace for about 70 cm relative to the west side of the fault. Most of the reported damage occurred near the fault. Around the Lingding Fault, most reported surface ruptures and landslides occurred at the northern section of the Coastal Range, which moved northward for about 50 cm relative to the west side of the fault. Surface rupture of the Lingding Fault was observed from the northern tip of the Coastal Range to near Yuemei Bridge. In between two faults, the area showed significant subsidence regardless of their directions of horizontal coseismic motion. The subsidence can be as high as 50 cm near the southern end of the Milun Fault.