Rapid Inversion of Fault Slip Distribution for Strong Earthquakes Along the Anninghe Fault Based on High-Rate GNSS

Objectives Infrequent strong earthquakes which occur on subduction and intraplate faults worldwide can be extremely destructive. The exploration on the reliability and timeliness of high-rate global navigation satellite system(GNSS) continuous stations can help rapid inversion of slip distribution and rapid estimation of earthquake magnitude. Especially for the Anninghe fault with high potential for strong earthquakes, this research has important practical significance for early warning of strong earthquakes in this region.

Methods We adopt a kinematic simulation method to synthesize stochastic rupture scenarios by incorporating the geodetic fault coupling model as prior constraints. For the Anninghe fault, we synthesize 1 100 earthquake events from Mw 6.5 to 7.5 and rupture scenarios, and simulate displacement waveforms by using random noise signals from the existing and newly built GNSS stations. These waveforms are analyzed the reliability of fault slip distribution along the Anninghe fault in combination with the steepest descent method.

Results For these events along the Anninghe fault, the initial inversion magnitude of Mw 6.2 can be determined in about 8 s after the earthquake using the existing GNSS continuous stations. And the magnitude and slip distributions can be obtained within a short time or before the rupture completes. The GNSS continuous stations of the China earthquake science experimental field, which is about to be built, can not only effectively obtain the magnitudes and slip distributions, but also determine the dominant directions of fault rupture.

Conclusions The feasibility and usefulness of the high-rate GNSS data are confirmed in magnitude estimation and finite-fault slip inversion of strong earthquakes along the Anninghe fault. It can provide theoretical basis and technical support for earthquake early warning in this region.