1. Geomagnetism

Magnetotelluric characterization of the Alhama de Murcia Fault (Eastern Betics, Spain) and study of magnetotelluric interstation impedance inversion

The Lorca earthquake (May 11th, 2011, Mw 5.2) stands as the most destructive one in Spain over the last 50 years, interpreted as having occurred in an intersegment zone of the strike–slip Alhama de Murcia Faul...

Authors: Anna Martí, Pilar Queralt, Alex Marcuello, Juanjo Ledo, Emilio Rodríguez-Escudero, José Jesús Martínez-Díaz, Joan Campanyà and Naser Meqbel

Validity of the dispersion relations in magnetotellurics: Part I—theory

Application of the dispersion relations (DR) in magnetotellurics (MT) is an efficient tool of post-processing and quality assessment of broadband field data. The main limitation of the approach is that it requ...

Authors: Nikita Zorin, Elena Aleksanova, Hisayoshi Shimizu and Denis Yakovlev

Evidence for terrane boundaries and suture zones across Southern Mongolia detected with a 2-dimensional magnetotelluric transect

Southern Mongolia is part of the Central Asian Orogenic Belt, the origin and evolution of which is not fully known and is often debated. It is composed of several east–west trending lithostratigraphic domains ...

Authors: Matthew J. Comeau, Michael Becken, Johannes S. Käufl, Alexander V. Grayver, Alexey V. Kuvshinov, Shoovdor Tserendug, Erdenechimeg Batmagnai and Sodnomsambuu Demberel

Seawater motion-induced electromagnetic noise reduction in marine magnetotelluric data using current meters

Seawater motion-induced electromagnetic (EM) noise along the seafloor has a large impact on marine magnetotelluric (MT) data quality. Although the mechanical stability of ocean bottom electromagnetic receivers...

Authors: Kai Chen, Qingxian Zhao, Ming Deng, Xianhu Luo and Jianen Jing

Quality over quantity: on workflow and model space exploration of 3D inversion of MT data

3D inversions of magnetotelluric data are now almost standard, with computational power now allowing an inversion to be performed in a matter of days (or hours) rather than weeks. However, when compared to 2D ...

Authors: K. Robertson, S. Thiel and N. Meqbel

Numerical simulations to explain the coseismic electromagnetic signals: a case study for a M5.4 aftershock of the 2016 Kumamoto earthquake

Coseismic electromagnetic (EM) signals that appear from the P arrival were observed in a volcanic area during the 2016 Kumamoto earthquake. In this study, we conduct numerical simulations to explain the coseis...

Authors: Yao-Chong Sun, Makoto Uyeshima, Hengxin Ren, Qinghua Huang, Koki Aizawa, Kaori Tsukamoto, Wataru Kanda, Kaori Seki, Takahiro Kishita, Takao Ohminato, Atsushi Watanabe, Jiangjun Ran and Xiaofei Chen

Uncertainty in hourly mean data from classical magnetometers

Hourly mean values obtained from analog magnetometers in what can be considered the “classical” period constitute the largest quantity of data we have on the evolution of the Earth’s magnetic field. They are u...

Authors: J. J. Curto

Effect of data error correlations on trans-dimensional MT Bayesian inversions

Real magnetotelluric (MT) data errors are commonly correlated, but MT inversions routinely neglect such correlations without an investigation on the impact of this simplification. This paper applies a hierarch...

Authors: Rongwen Guo, Liming Liu, Jianxin Liu, Ya Sun and Rong Liu

Magnetic dating of the Holocene monogenetic Tkarsheti volcano in the Kazbeki region (Great Caucasus)

The radiocarbon technique is widely used to date Late Pleistocene and Holocene lava flows. The significant difference with palaeomagnetic methods is that the ¹⁴C dating is performed on the organic matter carboniz...

Authors: Goga Vashakidze, Avto Goguitchaichvili, Natalia García-Redondo, Manuel Calvo-Rathert, Ángel Carrancho, Ruben Cejudo, Juan Morales, Vladimir A. Lebedev and Ketino Gabarashvili

Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity

Finding the statistical intensity signatures of the Earth’s magnetic field over geologic time has helped understanding of the evolution of the Earth’s interior and its interactions with other integral parts of...

Authors: Hyeon-Seon Ahn and Yuhji Yamamoto

First in-orbit results of the vector magnetic field measurement of the High Precision Magnetometer onboard the China Seismo-Electromagnetic Satellite

The High Precision Magnetometer (HPM) is one of the main payloads onboard the China Seismo-Electromagnetic Satellite (CSES). The HPM consists of two Fluxgate Magnetometers (FGM) and the Coupled Dark State Magn...

Authors: Bin Zhou, Bingjun Cheng, Xiaochen Gou, Lei Li, Yiteng Zhang, Jindong Wang, Werner Magnes, Roland Lammegger, Andreas Pollinger, Michaela Ellmeier, Qi Xiao, Xinghong Zhu, Shigeng Yuan, Yanyan Yang and Xuhui Shen

Electrical resistivity modeling around the Hidaka collision zone, northern Japan: regional structural background of the 2018 Hokkaido Eastern Iburi earthquake (M_w 6.6)

The Hidaka collision zone, the collision boundary between the NE Japan and Kurile arcs, is known to be an ideal region to study the evolution of island arcs. The hypocenter of the 2018 Hokkaido Eastern Iburi e...

Authors: Hiroshi Ichihara, Toru Mogi, Hideyuki Satoh and Yusuke Yamaya

Multi-order vector finite element modeling of 3D magnetotelluric data including complex geometry and anisotropy

We introduce MoVFEM, a computational algorithm for the modeling of three-dimensional magnetotelluric (MT) data using a vector finite element method of specific order from multiple elements’ orders. Our algorit...

Authors: Aixa M. Rivera-Rios, Bing Zhou, Graham Heinson and Lars Krieger

Wavelet-based verification of a relative paleointensity record from the North Pacific

We present a relative paleointensity (RPI) record for the last ~ 1.1 Myr estimated from a sediment core in the central North Pacific, with quality verification using wavelet analysis. Rock magnetic analysis re...

Authors: Ji Young Shin, Yongjae Yu and Wonnyon Kim

Studies on the relationships of the Curie surface with heat flow and crustal structures in Yunnan Province, China, and its adjacent areas

A Curie surface indicates the distribution of the thermal fields underground, providing a clear marker for the thermodynamic effect in the crust and mantle. In this paper, based on a geomagnetic field model (N...

Authors: Limin Wen, Guofa Kang, Chunhua Bai and Guoming Gao

The Iceland Palaeomagnetism Database (ICEPMAG)

The extensive lava piles of Iceland contain a unique record of geomagnetic field variations spanning the past ~ 16 Ma. Since the 1950s, palaeomagnetic data have been obtained from over 9400 Icelandic lavas. We...

Authors: Justin A. D. Tonti-Filippini and Maxwell C. Brown

A comprehensive paleomagnetic study from the last Plinian eruptions of Popocatepetl volcano: absolute chronology of lavas and estimation of emplacement temperatures of PDCs

Three lava flows (Buenavista, Xalitzintla and Nealtican) and pyroclastic density currents (Lorenzo and Pink Pumice) from two Popocatepetl Plinian eruptions were sampled for paleomagnetic dating. A detailed roc...

Authors: Nayeli Pérez-Rodríguez, Juan Morales, Avto Goguitchaichvili and Felipe García-Tenorio

3-D inversion of magnetic data based on the L1–L2 norm regularization

Magnetic inversion is one of the popular methods to obtain information about the subsurface structure. However, many of the conventional methods have a serious problem, that is, the linear equations to be solv...

Authors: Mitsuru Utsugi

Special issue “Recent advances in geo-, paleo- and rock-magnetism”

Authors: John A. Tarduno, Hirokuni Oda, Yuhji Yamamoto, Chuang Xuan, Ioan Lascu and Koji Fukuma

Modelling of electromagnetic signatures of global ocean circulation: physical approximations and numerical issues

The interactions of flowing electrically conductive seawater with Earth’s magnetic field generate electric currents within the oceans, as well as secondary electric currents induced in the resistive solid Eart...

Authors: Libor Šachl, Zdeněk Martinec, Jakub Velímský, Christopher Irrgang, Johannes Petereit, Jan Saynisch, David Einšpigel and Neesha Regmi Schnepf

Magnetotelluric transect of Unzen graben, Japan: conductors associated with normal faults

We conducted a broadband magnetotelluric (MT) survey along a north–south transect across Unzen graben, Japan. The MT survey line is located ~ 2 km west of the most recent lava dome and consisted of 27 stations...

Authors: Agnis Triahadini, Koki Aizawa, Yoshiko Teguri, Takao Koyama, Kaori Tsukamoto, Dan Muramatsu, Keita Chiba and Makoto Uyeshima

Investigation of regional variation in core flow models using spherical Slepian functions

By assuming that changes in the magnetic field in the Earth’s outer core are advection-dominated on short timescales, models of the core surface flow can be deduced from secular variation. Such models are know...

Authors: Hannah F. Rogers, Ciarán D. Beggan and Kathryn A. Whaler

Tippers at island geomagnetic observatories constrain electrical conductivity of oceanic lithosphere and upper mantle

Geomagnetic field variations as recorded at geomagnetic observatories are important for global electromagnetic studies. However, this data set is rarely used for studying the local electrical conductivity at d...

Authors: Achim Morschhauser, Alexander Grayver, Alexey Kuvshinov, Friedemann Samrock and Jürgen Matzka

Using TNT-NN to unlock the fast full spatial inversion of large magnetic microscopy data sets

Modern magnetic microscopy (MM) provides high-resolution, ultra-high-sensitivity moment magnetometry, with the ability to measure at spatial resolutions better than ...

Authors: Joseph M. Myre, Ioan Lascu, Eduardo A. Lima, Joshua M. Feinberg, Martin O. Saar and Benjamin P. Weiss

The effects of dislocations on crystallographic twins and domain wall motion in magnetite at the Verwey transition

Pure magnetite experiences a first-order phase transition (the Verwey transition) near 120–125 K wherein the mineral’s symmetry changes from cubic to monoclinic. This transformation results in the formation of...

Authors: Anna K. Lindquist, Joshua M. Feinberg, Richard J. Harrison, James C. Loudon and Andrew J. Newell

3-D inversion of MT impedances and inter-site tensors, individually and jointly. New lessons learnt

A conventional magnetotelluric (MT) survey layout implies measurements of horizontal electric and magnetic fields at every site with subsequent estimation and interpretation of impedance tensors

Authors: Mikhail Kruglyakov and Alexey Kuvshinov

Temporal resolution of internal magnetic field modes from satellite data

We aim to obtain a modal decomposition of the internal geomagnetic field. In order to do so, we perform a principal component analysis of two virtual observatory datasets, with 4-month sampling time, from the ...

Authors: João Domingos, Maria Alexandra Pais, Dominique Jault and Mioara Mandea

Constraining the magnetic properties of ultrafine- and fine-grained biogenic magnetite

Four samples containing ultrafine- and fine-grained magnetite of magnetoferritins and magnetotactic bacteria cells were magnetically characterized at both room and low temperatures. Transmission electron micro...

Authors: Tongwei Zhang and Yongxin Pan

Seafloor hydrothermal alteration affecting magnetic properties of abyssal basaltic rocks: insights from back-arc lavas of the Okinawa Trough

Seafloor hydrothermal systems in the back-arc region of the Okinawa Trough have been viewed as a modern analogue to the Kuroko-type volcanogenic massive sulfide deposits. Detection of magnetic signatures is wi...

Authors: Masakazu Fujii, Hiroshi Sato, Eri Togawa, Kazuhiko Shimada and Jun-ichiro Ishibashi

On the modelling of M₂ tidal magnetic signatures: effects of physical approximations and numerical resolution

Authors: Jakub Velímský, Alexander Grayver, Alexey Kuvshinov and Libor Šachl

Inflation and collapse of the Wai’anae volcano (Oahu, Hawaii, USA): implications from rock magnetic properties and magnetic fabric data of dikes

In order to investigate the role of dikes in the volcanic evolution and the triggering mechanisms of catastrophic mass wasting volcanoes, we have sampled for a pilot study, seven dikes within the Wai’anae volc...

Authors: Emilio Herrero-Bervera, Bernard Henry and Mário Moreira

Near-seafloor magnetic mapping of off-axis lava flows near the Kairei and Yokoniwa hydrothermal vent fields in the Central Indian Ridge

The Kairei (KHF) and Yokoniwa hydrothermal fields (YHF) are hosted in mafic as well as ultramafic rocks distributed at an off-axis volcanic knoll of the Central Indian Ridge. Despite intensive investigations, ...

Authors: Masakazu Fujii and Kyoko Okino

Reductive chemical demagnetization: a new approach to magnetic cleaning and a case study of reef limestones

Chemical demagnetization is not preferred as a demagnetizing method in paleomagnetism because strong acids are cumbersome to handle and require considerable time compared to alternating field and thermal demag...

Authors: Chisato Anai, Nobutatsu Mochizuki and Hidetoshi Shibuya

Sources of the lithosphere magnetic field based on magnetic data obtained at different heights

Our investigations are based on the property that the fields of sources, whose depths are numerically equal to survey heights, are most brightly presented in the data of magnetic survey. Therefore, the magneti...

Authors: Yury P. Tsvetkov, Konstantin V. Novikov, Andrey A. Ivanov and Oleg M. Brekhov

A 3D electrical resistivity model around the focal zone of the 2017 southern Nagano Prefecture earthquake (M_JMA 5.6): implications for relationship between seismicity and crustal heterogeneity

Seismic swarm areas below the southeast flank of Ontake volcano, central Japan, provide an important opportunity to study interactions between seismicity, volcanic processes and crustal fluid. On June 25, 2017...

Authors: Hiroshi Ichihara, Junna Kanehiro, Toru Mogi, Koshun Yamaoka, Noriko Tada, Edward Alan Bertrand and Mamoru Adachi

Possible correlation between the vertical component of lithospheric magnetic field and continental seismicity

Recent magnetic satellite missions facilitate new birth of large-scale geomagnetic field models and their applications to tectonics. Here, we directly compare the global geomagnetic field models NGDC-720 with ...

Authors: Yu Lei, Liguo Jiao and Huaran Chen

Paleomagnetic studies on single crystals separated from the middle Cretaceous Iritono granite

Investigations of superchrons are the key to understanding long-term changes of the geodynamo and the mantle’s controlling role. Granitic rocks could be good recorders of deep-time geomagnetic field behavior, ...

Authors: Chie Kato, Masahiko Sato, Yuhji Yamamoto, Hideo Tsunakawa and Joseph L. Kirschvink

Characterization of marine ferromanganese crust from the Pacific using residues of selective chemical leaching: identification of fossil magnetotactic bacteria with FE-SEM and rock magnetic methods

Hydrogenetic ferromanganese crusts (hereafter referred to as “crusts”) on Pacific seamounts are formed by the precipitation of iron–manganese oxides from seawater on volcanic and biogenic substrate rocks. As c...

Authors: Hirokuni Oda, Yoshio Nakasato and Akira Usui

Remanence cycling of 0.6–135 µm magnetites across the Verwey transition

We report zero-field low-temperature cycling of saturation remanence (SIRM) produced at 300 or 10 K for crushed natural magnetites in nine size fractions from 0.6 to 135 µm, one set annealed to reduce stress, ...

Authors: David J. Dunlop and Özden Özdemir

Crustal structure of a young collision zone: the Arabia–Eurasia collision in northeastern Turkey investigated by magnetotelluric data

The northeastern Turkey is located at the intensely deformed east Anatolian Collision Zone that is formed by the collision of the Arabian Plate with Eurasia. The region is one of the best examples of the conti...

Authors: Özlem Hacıoğlu, Ahmet Tuğrul Başokur and Elif Tolak Çiftçi

An initial case study to deconvolve natural remanent magnetization of a continuous paleomagnetic sample using the software UDECON

Previous studies have compiled relative paleointensity data for the last 2–3 Ma from individual paleomagnetic records obtained from marine sediment cores. These records have mostly been obtained by pass-throug...

Authors: Yuhji Yamamoto, Toshitsugu Yamazaki and Toshiya Kanamatsu

Rock magnetism of quartz and feldspars chemically separated from pelagic red clay: a new approach to provenance study

Magnetic mineral inclusions in silicates are widespread in sediments as well as in igneous rocks. Because they are isolated from surrounding environment, they have potential to preserve original magnetic signa...

Authors: Yoichi Usui, Takaya Shimono and Toshitsugu Yamazaki

A generating process of geomagnetic drifting field

The geomagnetic field is comprised of drifting and standing fields. The drifting field has two remarkable features. One is predominance of sectorial harmonics when the field is expressed in a spherical harmoni...

Authors: Takesi Yukutake and Hisayoshi Shimizu

Online plotting applications for paleomagnetic and rock magnetic data

This paper describes the development and release of a series of web-based services to generate plots of paleomagnetic and rock magnetic data. All plotting services require a World Wide Web browser as the user ...

Authors: Tadahiro Hatakeyama

Invariant TE and TM magnetotelluric impedances: application to the BC87 dataset

Invariants under rotation of the magnetotelluric impedance tensor relax the directional requirements when fitting data using two-dimensional (2D) models. This happens, for instance, when using the familiar imp...

Authors: Enrique Gómez-Treviño, Yunuhen Muñiz, Mayra Cuellar and Armando Calderón-Moctezuma

A comprehensive model of Earth’s magnetic field determined from 4 years of Swarm satellite observations

The European Space Agency’s three-satellite constellation Swarm, launched in November 2013, has provided unprecedented monitoring of Earth’s magnetic field via a unique set of gradiometric and multi-satellite mea...

Authors: Terence J. Sabaka, Lars Tøffner-Clausen, Nils Olsen and Christopher C. Finlay

A new miniaturized magnetometer system for long-term distributed observation on the seafloor

We have developed a new magnetometer system specialized to multipoint and long-term observations on the seafloor to promote marine or ocean-bottom experiments mainly for the electromagnetic sounding of the Ear...

Authors: Kazunori Ogawa, Tetsuo Matsuno, Hiroshi Ichihara, Kazuo Nakahigashi and Nobukazu Seama

Hybrid finite difference–finite element method to incorporate topography and bathymetry for two-dimensional magnetotelluric modeling

In this research, a new numerical method, called the hybrid finite difference–finite element (hybrid FD–FE) method, is developed to solve 2-D magnetotelluric modeling by taking advantage of both the finite dif...

Authors: Weerachai Sarakorn and Chatchai Vachiratienchai

Comparison of global geomagnetic field models and evaluation using marine datasets in the north-eastern Atlantic Ocean and western Mediterranean Sea

Many models describing the Earth’s magnetic field exist and are maintained by international research organizations. However, no clear general overview of the cross-compared quality of these models is available...

Authors: Jean-François Oehler, Didier Rouxel and Marie-Françoise Lequentrec-Lalancette

Preliminary paleomagnetic and rock magnetic results from 17 to 22 ka sediment of Jeju Island, Korea: Geomagnetic excursional behavior or rock magnetic anomalies?

Paleomagnetic and rock magnetic investigations were performed on a 64-cm-thick section of nonmarine unconsolidated muddy sediment from the Gosan Formation on Jeju Island, Korea. This sediment was recently date...

Authors: Hyeon-Seon Ahn, Young Kwan Sohn, Jin-Young Lee and Jin Cheul Kim