1. Geomagnetism

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

Archeointensity estimates of a tenth-century kiln: first application of the Tsunakawa–Shaw paleointensity method to archeological relics

Paleomagnetic information reconstructed from archeological materials can be utilized to estimate the archeological age of excavated relics, in addition to revealing the geomagnetic secular variation and core d...

Authors: Yu Kitahara, Yuhji Yamamoto, Masao Ohno, Yoshihiro Kuwahara, Shuichi Kameda and Tadahiro Hatakeyama

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

Cross-validation of independent ultra-low-frequency magnetic recording systems for active fault studies

When working with ultra-low-frequency (ULF) magnetic datasets, as with most geophysical time-series data, it is important to be able to distinguish between cultural signals, internal instrument noise, and natu...

Authors: Can Wang, Chen Bin, Lilianna E. Christman, Jonathan M. G. Glen, Simon L. Klemperer, Darcy K. McPhee, Karl N. Kappler, Tom E. Bleier and J. Clark Dunson

Special issue “Studies on electromagnetic induction in the earth: recent advances”

Authors: Weerachai Siripunvaraporn, Paul A. Bedrosian, Yuguo Li, Prasanta K. Patro, Klaus Spitzer and Hiroaki Toh

Electrical resistivity structure at the North-Central Turkey inferred from three-dimensional magnetotellurics

Magnetotelluric data analyses and three-dimensional modeling techniques were implemented to investigate the crustal electrical structure in the North-Central Turkey, along a 190-km-long profile crossing Çankır...

Authors: Sinan Özaydın, Sabri Bülent Tank and Mustafa Karaş

A paleomagnetic record in loess–paleosol sequences since late Pleistocene in the arid Central Asia

Geomagnetic excursions during Brunhes epoch have been brought to the forefront topic in paleomagnetic study, as they provide key information about Earth’s interior dynamics and could serve as another tool for ...

Authors: Guanhua Li, Dunsheng Xia, Erwin Appel, Youjun Wang, Jia Jia and Xiaoqiang Yang

Geoelectric hazard assessment: the differences of geoelectric responses during magnetic storms within common physiographic zones

Geomagnetic field data obtained through the INTERMAGNET program are convolved with with magnetotelluric surface impedance from four EarthScope USArray sites to estimate the geoelectric variations throughout th...

Authors: Stephen W. Cuttler, Jeffrey J. Love and Andrei Swidinsky

A harmonic spline magnetic main field model for Southern Africa combining ground and satellite data to describe the evolution of the South Atlantic Anomaly in this region between 2005 and 2010

CHAMP satellite and relatively densely spaced ground-based data measured over southern Africa between 2005 and 2010 are combined in a new regional, harmonic spline based, core field model. This new SACFM-2 mod...

Authors: Emmanuel Nahayo, Pieter B. Kotzé, Monika Korte and Susan J. Webb

Time-lapse inversion of one-dimensional magnetotelluric data

We present a new tool for modelling time-lapse magnetotelluric (MT) data, an emerging technique for monitoring changes in subsurface electrical resistivity. Time-lapse MT data have been acquired in various set...

Authors: Dennis Conway, Graham Heinson, Nigel Rees and Joseph Rugari

On the feasibility of routine baseline improvement in processing of geomagnetic observatory data

We propose a new approach to the calculation of regular baselines at magnetic observatories. The proposed approach is based on the simultaneous analysis of the irregular absolute observations and the continuou...

Authors: Anatoly Soloviev, Vincent Lesur and Dmitry Kudin

Source biases in midlatitude magnetotelluric transfer functions due to Pc3-4 geomagnetic pulsations

The magnetotelluric (MT) method for imaging the electrical conductivity structure of the Earth is based on the assumption that source magnetic fields can be considered quasi-uniform, such that the spatial scal...

Authors: Benjamin S. Murphy and Gary D. Egbert

Do ocean tidal signals influence recovery of solar quiet variations?

The solar quiet (Sq) source morphology changes on a daily basis and becomes disturbed during periods of increased magnetic activity. Therefore, it may be preferable to use single-day magnetic field recordings ...

Authors: Martina Guzavina, Alexander Grayver and Alexey Kuvshinov

Monitoring hydraulic stimulation using telluric sounding

The telluric sounding (TS) method is introduced as a potential tool for monitoring hydraulic fracturing at depth. The advantage of this technique is that it requires only the measurement of electric fields, wh...

Authors: Nigel Rees, Graham Heinson and Dennis Conway

Regularized magnetotelluric inversion based on a minimum support gradient stabilizing functional

Regularization is used to solve the ill-posed problem of magnetotelluric inversion usually by adding a stabilizing functional to the objective functional that allows us to obtain a stable solution. Among a num...

Authors: Yang Xiang, Peng Yu, Luolei Zhang, Shaokong Feng and Hisashi Utada

Electrical conductivity of the global ocean

The electrical conductivity of the ocean is a fundamental parameter in the electrodynamics of the Earth System. This parameter is involved in a number of applications ranging from the calibration of in situ oc...

Authors: Robert H. Tyler, Tim P. Boyer, Takuto Minami, Melissa M. Zweng and James R. Reagan

Core surface sub-centennial magnetic flux patches: characteristics and evolution

Short-term constituents of the secular variation, at inter-decadal (20–30 years) and sub-centennial (60–90 years) time scales, present in observatory data and main field models, are also found in the radial fi...

Authors: C. Stefan, V. Dobrica and C. Demetrescu

Varying Indian crustal front in the southern Tibetan Plateau as revealed by magnetotelluric data

In the southern Tibetan plateau, which is considered to be the ongoing India–Eurasia continental collision zone, tracing of the Indian crustal front beneath Tibet is still controversial. We conducted deep subs...

Authors: Chengliang Xie, Sheng Jin, Wenbo Wei, Gaofeng Ye, Letian Zhang, Hao Dong and Yaotian Yin