Aubreya N. Adams | Geology Reports

USGS2026

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 × 10 6 m 3 . 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.

Ol Doinyo Lengai↗

USGS2020

The Alaska Amphibious Community Seismic Experiment

The Alaska Amphibious Community Seismic Experiment (AACSE) is a shoreline‐crossing passive‐ and active‐source seismic experiment that took place from May 2018 through August 2019 along an ∼ 700    km "> ∼ 700 km ∼700 km long section of the Aleutian subduction zone spanning Kodiak Island and the Alaska Peninsula. The experiment featured 105 broadband seismometers; 30 were deployed onshore, and 75 were deployed offshore in Ocean Bottom Seismometer (OBS) packages. Additional strong‐motion instruments were also deployed at six onshore seismic sites. Offshore OBS stretched from the outer rise across the trench to the shelf. OBSs in shallow water ( ⁠ < 262    m "> < 262 m <262 m depth) were deployed with a trawl‐resistant shield, and deeper OBSs were unshielded. Additionally, a number of OBS‐mounted strong‐motion instruments, differential and absolute pressure gauges, hydrophones, and temperature and salinity sensors were deployed. OBSs were deployed on two cruises of the R/V Sikuliaq in May and July 2018 and retrieved on two cruises aboard the R/V Sikuliaq and R/V Langseth in August–September 2019. A complementary 398‐instrument nodal seismometer array was deployed on Kodiak Island for four weeks in May–June 2019, and an active‐source seismic survey on the R/V Langseth was arranged in June 2019 to shoot into the AACSE broadband network and the nodes. Additional underway data from cruises include seafloor bathymetry and sub‐bottom profiles, with extra data collected near the rupture zone of the 2018 M w "> M w Mw 7.9 offshore‐Kodiak earthquake. The AACSE network was deployed simultaneously with the EarthScope Transportable Array (TA) in Alaska, effectively densifying and extending the TA offshore in the region of the Alaska Peninsula. AACSE is a community experiment, and all data were made available publicly as soon as feasible in appropriate repositories.

Alaska↗