Strain Accumulation Along the Eastern Java Back–Arc Thrust System Inferred from a Dense Global Navigation Satellite System Network

The back–arc thrust region in Eastern Java to Flores is significantly influenced by the arc–continent collision between the Australian Plate and the Eastern Sunda Arc, leading to a tectonic regime characterized by high seismic and volcanic hazards. This area has experienced several major earthquakes. However, back–arc thrust in Eastern Java remains absent from significant shallow earthquakes, which might indicate intense deformation. We conducted an analysis using recent and dense Global Navigation Satellite System (GNSS) observations from both continuous and campaign stations to develop a strain rate model and explore the detailed crustal behavior and strain accumulation within the Eastern Java back–arc thrust system. Our findings revealed varying values of compression and extension throughout the region, with compression values ranging from −2.24 to 0.086 μstrain/year. Additionally, we observed that the maximum shear strain rate and dilatation strain rate were within the ranges of 0.0013 to 1.12 μstrain/year and −2.24 to 0.698 μstrain/year, respectively. These findings could facilitate more informed strategies and improve preparedness for future seismic events.