Fig. 1 | Scientific Reports

Fig. 1

From: Waveform cross-correlation analysis and magnitude estimation for the 1887 Ligurian earthquake determined from magnetogram recordings

Fig. 1The alternative text for this image may have been generated using AI.

Horizontal-force (H) and declination (D) traces recorded by the magnetometer at the Greenwich observatory, capturing variations in the Earth’s magnetic field. Notably, the original annotations from 1887 highlight the disturbances caused by the Ligurian earthquake on 23 February. The enlarged section emphasizes the exact time at which the seismic waves, referred to as “disturbances,” were detected (5:38 a.m.). The red trace represents the part of the signal that was digitized (see “Magnetogram digitization” section for more details) and subsequently used for all further analyses. Reproduced with the permission of the BGS \(\copyright\) UKRI 2025 \(\copyright\) NERC 2025. All rights reserved..

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