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A forward marine magnetic modeling program


Concepts in Magellan




What is Magellan?

Magellan is an open source marine magnetic modeling program. It is based on the forward method of modeling where the user tweaks parameters (spreading rates, jumps, magnetization, etc.) of the model until a good fit has been made to actual observations. It produces figures with the magnetic model and measurements, pseudofaults and failed rifts, along with bathymetry and arrangement of the magnetized blocks.

Magellan is developed and maintained by Ásdís Benediktsdóttir and Tryggvi Björgvinsson and released under the GNU General Public License.

Magellan is free to download and comes with a tutorial.

The Basics of Magellan

As new oceanic lithosphere is created, at spreading centers, it gets magnetized in the direction of Earth's current magnetic field. Earth's magnetic field reverses every now and then meaning that the magnetic poles change positions (north pole goes where south pole was and vice versa). This phenomenon produces a series of normal and reversed magnetized stripes parallel to the ridge. If the spreading of the ridge is symmetric, then these stripes are symmetric about the ridge.

Magnetic data are usually collected perpendicular to a ridge (in the direction of spreading). This is done using a magnetometer that is towed behind a ship or positioned in an airplane (aeromagnetic survey). After the Earth's magnetic field has been subtracted from the magnetic data we are left with data that are usually referred to as 'magnetic anomalies' and arise from the thermal magnetization of the sea floor. Magellan's purpose is to fit these anomalies so the kinematic characteristics of the ridge can be obtained.