Inflation at Ol Doinyo Lengai driven by shallow magma intrusion during the 2022–2023 uplift episode in an early-phase continental rift

The active stratovolcano Ol Doinyo Lengai is located in the magma-rich, early-phase continental Natron Rift, which is part of the larger East African Rift System. Since 2016, a geodetic network comprising 7 Global Navigation Satellite Navigation (GNSS) and 2 seismic stations has been deployed to monitor inflation and deflation around this volcano. Between March 2022 and August 2023, millimeter-precision GNSS data detected a non-eruptive uplift episode at Ol Doinyo Lengai. In this work, we explore potential drivers of the uplift event by inverting GNSS data using the open-source software package dMODELS developed by the US Geological Survey. We assess four mathematical models (spherical, sill-like, spheroid, dislocation/dike) and find the best-fit solution is consistent with an intrusion of magma from a shallow, sill-like source at approximately 3.1 ± 2.2 km depth below the summit with a volume change of 0.99 ± 0.22 × 10⁶ m³. Although continuous GNSS observations of surface motions at Ol Doinyo Lengai are relatively short, having only begun in 2016, this work contributes to our understanding of the ongoing magmatic processes and its long-term deformation cycle, allowing for improved volcanic hazards assessment and comparisons with global volcanic systems.