High‐fidelity paleointensity determination from historic volcanoes in Japan

Providing high‐fidelity paleointensity estimates is pivotal to identify temporal fluctuation of ancient geomagnetic field. Despite abundance of available paleointensity data in Japan, only dozen of them satisfy modern standards with systematic alteration checks. High‐fidelity paleointensity estimates were obtained from historic andesitic lavas collected from Mt. Aso (Ojodake, ≈700 BC), Mt. Kirishima (Iwoyama, AD 1768; Ohachi, AD 1235), and Mt. Sakurajima (An‐ei, AD 1779; Nabeyama, AD 764–766). Variation of geomagnetic field intensity is distinctively different from the prediction of global models (ARCH3k.1, CALS3k.3, CALS3k.4, CALS7k.2, and CALS10k.1b) for the past 4000 years in Japan. The compilation of high‐fidelity Thellier data set in Japan showed two obvious high intensities at AD 590–765 and AD 1330–1435 and one low intensity at ≈700 BC. These time intervals with anomalous high/low intensities are nearly identical to three of the four potential archeomagnetic jerks recognized from the European archeomagnetic data, implying that the archeomagnetic jerks were global (or at least northern hemispheric) features. To improve the poor representation of regional geomagnetic field variation with respect to the global model prediction, more high‐fidelity paleointensity determinations are required in East Asia.