Triggering of eruptions at Axial Seamount, Juan de Fuca Ridge

Area of Science:

• Geophysics
• Volcanology
• Tectonophysics

Background:

• Axial Seamount exhibits predictable inflation-eruption cycles, enabling successful eruption forecasting.
• The precise eruption triggering mechanism at Axial Seamount remains unclear.
• Existing models propose either magma reservoir overpressure or host rock critical stress as triggers.

Purpose of the Study:

• To test hypotheses regarding eruption triggering mechanisms at Axial Seamount.
• To investigate the role of host rock stress and magma reservoir pressure in eruption initiation.
• To assess the influence of rheology and external stresses on volcanic deformation and eruption timing.

Main Methods:

• Utilized 3-dimensional finite element models to simulate stress evolution and mechanical failure in the host rock.
• Tracked stress changes around the Axial magma reservoir.
• Assessed model sensitivity to temperature-dependent and independent rheologies and external tectonic stresses.

Main Results:

• Models consistently predict eruptions at a reservoir pressure threshold of 12-14 MPa.
• The timing of predicted eruptions was significantly impacted by the assumed model rheology.
• Despite rheological variations, the overpressure threshold remained consistent.

Conclusions:

• Findings support the interpretation that Axial Seamount eruptions are primarily triggered by reservoir overpressurization.
• Host rock stress conditions alone may not be the sole determinant of eruption timing.
• Understanding rheological properties is crucial for refining volcanic deformation and eruption forecasts.