Abstract Magnetic surveys are used to identify and monitor hydrothermally altered regions on volcanoes. Commonly such magnetic data interpreted the premise that hydrothermal alteration consumes Fe‐Ti oxides in host rocks, reducing their total magnetization. Here, we report a contrasting observation from Whakaari (White Island) volcano New Zealand. We study properties of 42 conduit‐filling surfi...

We report on extensive Monte Carlo simulations of diluted Ising-type antiferromagnets in a uniform magnetic field in three dimensions. The analysis of the relaxation data of the domain state leads to a power-law decay of the remanent magnetization and internal energy. The corresponding exponents are proportional to the temperature. The power noise spectrum is investigated, showing roughly 1 / !...