Scientists demystify stress changes before mainshocks and utilize the foreshocks as an indicator. We investigate changes in seismicity far from mainshocks by using tens of thousands of M ≥ 2 quakes for 10 years in Taiwan and Japan. The results show that wide areas exhibit increased seismicity occurring more than several times in areas of the fault rupture. The stressed crust triggers resonance at frequencies varying from ~ 5 × 10–4 to ~ 10–3 Hz that is supported by the resonant frequency model.

In this paper, we report on observations of frequency-banded wave emissions by ICE (Instrument Champ Électrique) on board DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions). We distinguish two components: positive and negative frequency drift rates and multiple spaced frequency bands near the magnetic equatorial plane. We show and discuss the non-free-space DEMETER frequency-banded emissions and the free-space terrestrial kilometric radiation.

Identifying ionospheric disturbances associated with an earthquake is a useful and challenging work. A new decomposition and nonlinear fitting method has been developed to analyze ionospheric total electron content (TEC) data, and to extract disturbances that are likely related to Mw7.2 Mexico earthquake occurred on April 4, 2010. We found a unique TEC depletion that occurred around the epicenter on March 25, which cannot be explained by lower atmosphere wave or geomagnetic activity forcing.

Raw output of spacecraft magnetometers has to be converted into meaningful units and coordinate systems before it is usable for scientific applications. This conversion is defined by 12 calibration parameters, 8 of which are more easily determined in flight if the spacecraft is spinning. We present theory and advanced algorithms to determine these eight parameters. They take into account the physical magnetometer and spacecraft behavior, making them superior to previously published algorithms.

This paper describes frequency and timing calibration, modeling and data processing and calibration for MMS magnetometers, resulting in a merged search choil and fluxgate data product.