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On 19 December 2009, the eastern part of Taiwan at approximate depth of 45 km was struck by a strong earthquake (Mw = 6.4). The epicenter was located about 20 km away from the Hualien (HLN) station in Taiwan. By analyzing data from the HLN station and Amami Oshima (AMA) in Japan as a remote reference, the geomagnetic east-west (D) and vertical (Z) components recorded at the HLN station are showing no correlation with those at the AMA station in December 2009. Anomalous variations of ∼10-15 nT started about one week before the occurrence of the earthquake and lasted for about two weeks. Also, an enhanced ULF signal in the range of Pc 3 (10-40 s) was observed a few days before the onset of the earthquake. Moreover, the polarization ratio (Z/H (north-south component)) of the Pc 3 amplitude at the HLN station decreased a few days preceding the earthquake. The mechanism behind these anomalous variations is not fully understood. However, we expect that crustal stress perturbations and underground conductivity changes associated with the earthquake played an important role for generating such observed geomagnetic variations. [ABSTRACT FROM AUTHOR]

The physical destruction and fatalities caused by earthquake events has compelled scientists to develop a method for predicting Earthquakes. It is almost impossible to detect earthquake events due to limited seismometer sensitivity; therefore, a non-seismological predictor was established by using the Ultra-Low Frequency (ULF) magnetic field as a potential earthquake precursor. ULF waves respond to magnetic activity that are transferred to Earth by solar winds, and become ultimately linked to earthquake events. The statistical correlation analysis is used between ULF Pc4 and Pc5 pulsation, solar wind parameters; IMF- component (Bz), solar wind speed (Vsw), solar wind pressure (Psw), solar wind input energy (IEsw), and near-equator geomagnetic storm (SYM/H). Through a multiple regression modelled approach, the relationship between solar wind (SW) parameters (IMF-Bz, Vsw, Psw, IEsw) and near-equator geomagnetic index (SYM/H) with ULF wave pulsations (Pc4 - Pc5) prior to an earthquake (EQ) event (magnitude, M = 3.0–6.0, depth, d < 100 km, epicentre distance from magnetometer station, r < 100 km) was determined. The solar wind and geomagnetic index parameters were obtained from OMNIWeb, where ULF pulsations (Pc4 - Pc5) were computed from the magnetometer Davao station (Philippines) (7.00 o N, 125.40 o E) located in a low latitude region. The ULF Pc5 band demonstrated the best fit for the ULF earthquake precursor model in relation to solar wind parameters (Vsw, Psw) and geomagnetic index (SYM/H) with R 2 and R 2-adjusted values of (R 2 =0.5011, R 2-adj = 0.4940). The Vsw, Psw and SYM/H are major factors that contribute to the emission of ULF Pc5 prior to an earthquake, as determined by the stepwise regression method. This ULF earthquake precursor model is intended to address the problem seismologists face when predicting seismic events by assisting non-seismologists in locating the most effective EM-ULF wave bands in solar-terrestrial activities for detecting seismic events. [ABSTRACT FROM AUTHOR]

Abstract: On 15 August 2007, Pisco earthquake (magnitude 8.0) hit the central coast of Peru near the MAGDAS Ancon (ANC) station. Geomagnetic data from ANC and other reference stations have been analyzed to detect any signature related to this great earthquake. Results indicate the presence of annual geomagnetic variations in the vertical component at ANC and Huancayo (HUA) stations (in the vicinity of the epicenter of Pisco earthquake). These variations have a quasi-sinusoidal waveform with amplitudes of about 10 and 5nT for ANC and HUA stations respectively. They appeared clearly during the period preceding the onset of the Pisco earthquake especially at ANC station. By using HUA, Eusebio (EUS) and Kourou (KOU) as reference stations in the vicinity and away from the epicenter of Pisco earthquake, a clear disappearance of the diurnal variation of the vertical component was observed at ANC station during the day of earthquake. Moreover, the Pisco earthquake and another earthquake (on 29 March 2008) near ANC station were found to occur concurrently with the depressions in the polarization ratio (Z/H) of Pc 3 (10–45s) amplitude. Such anomalous variations appear to be a result of changes in the crustal stress field and the lithospheric conductivity in the studied region. [Copyright &y& Elsevier]