Anomalous ultra low frequency signals possibly linked with seismic activities in Sumatra, Indonesia

Takla, E. M.; Khashaba, A.; Zaher, M. A.; Yoshikawa, Akimasa; Уозуми, Т.

doi:10.1016/j.nrjag.2018.04.004

Cited by 7 publications

(7 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In all the seismic events, peaks were seen both in the H and Z components, as well as in the filtered variation, as shown on Table 2. , 2018;5 July, 2018;21 and 26 September, 2018;11 October, 2018;and 5 April, 2019. Difference between magnetic data from KEP and ORC observatories.…”

Section: Resultsmentioning

confidence: 98%

See 1 more Smart Citation

Wavelet-based Characterization of Seismicity and Geomagnetic Disturbances in the South Sandwich Microplate Area

Larocca

Arecco²,

Mora³

2021

GeofInt

View full text Add to dashboard Cite

This paper analyzes geomagnetic disturbances associated with seismic events in the northern transcurrent margin of the South Sandwich microplate and South American plate, with their epicenter at distances within 350 km from King Edward Point geomagnetic observatory on the archipelago of the Georgias del Sur islands. Geomagnetic field records measured over a one-year period in three observatories of the INTERMAGNET network near the area under study are examined. Anomalous variations in geomagnetic records can be detected within approximately 3 hours before the manifestation of seismic events with a magnitude above 4.4 Mw. Based on the analysis of the differences in horizontal field components among the observatories and the frequency spectrum of the geomagnetic field observations using the wavelet method, oscillations of several nT can be observed before an event, in addition to magnetic peaks with variable amplitude and duration. It is worth noting that, during the period of study, no severe ionospheric effects were recorded as this was a phase of low solar activity (solar cycle 24 minimum). The observation of these potential magnetic precursors suggests that there is a critical preparatory period in a region with geological faults related to the stress generated in the rocks before the built-up energy is released in the hypocenter area, within the lithosphere, which may predict the mechanical motion based on anomalous geomagnetic records.

show abstract

Section: Resultsmentioning

confidence: 98%

“…The geomagnetic field is no exception. It was repeatedly observed that geomagnetic field disturbances occurred during the preparation stage of an earthquake (Kushwah et al, 2009;Ruiz et al, 2011;Takla et al, 2018).…”

Section: Introductionmentioning

confidence: 98%

Wavelet-based Characterization of Seismicity and Geomagnetic Disturbances in the South Sandwich Microplate Area

Larocca

Arecco²,

Mora³

2021

GeofInt

View full text Add to dashboard Cite

show abstract

“…Arecco et al (2023) [11] recorded abnormal sea height levels along the Argentine coast and Antarctic bases during the Mw 8.1 earthquake of August 12, 2021 in the Sandwich Islands, recording heights above 1.3 m in the South Georgia Islands. There are numerous studies reporting associations between earthquakes and physical phenomena, such as electromagnetic field variations (Varotsos et al, 2013 [12] ; Hayakawa et al, 2010 [13] ; Takeuchi et al, 2012 [14] ; Gao et al, 2014 [15] ; Zhao et al, 2021 [16] ), anomalous Geomagnetic Field (GMF) records on the earth's surface (Ruiz et al, 2011 [17] ; Takla et al, 2018 [18] ; Arecco et al, 2020 [19] ; Larocca et al, 2021 [20] )…”

Section: Introductionmentioning

confidence: 99%

Magnetogravimetric study on the Scotia Plate, in the South Atlantic Ocean for the characterization of tsunamis

Alejandra

2024

EAR

View full text Add to dashboard Cite

The marine and coastal environments of the Scotia Sea regions in the Southern Atlantic Ocean and Antarctica are vulnerable to the potentially disastrous effects of seismic activity along the Scotia Arc. This paper presents a magnetogravimetric study of the Scotia Plate for tsunami characterization. The influence of earthquakes on the Geomagnetic Field (GMF) is investigated using data from INTERMAGNET network observatories. A tectonic model is evaluated using gravity data from NOAA and seismic refraction data from Lamont-Doherty Earth Observatory. The study also assesses the impact on water level (WL) measured at Intergovernmental Oceanographic Commission (IOC) tide gauge stations. Cross Wavelet Transform (XWT) is applied, and a frequency analysis of the GMF is conducted to identify specific frequencies during seismic events. A 2D tectonic model is constructed for the North Scotia Ridge using gravimetric and seismic data to characterize structural boundaries that may be activated during seismic events. Water level records collected from 6 tide gauge stations in the region are filtered and analyzed to identify tsunamis at each station. The results reveal anomalous frequencies in the frequency analysis of the horizontal component of the GMF during the November 25, 2013 earthquake, with high data correlation from different observatories in the study area for periods of 0.5 and 1 hour. Gravimetric modeling delineates faults activated during seismic activity and edges of structures potentially activated due to the transcurrent and compressional nature of the margin. WL anomalies up to 1.30 m are obtained following earthquakes with a magnitude greater than 8. The propagation speed in the study area averaged 460 km/h, consistent with the expected speed for those depths, except for Puerto Argentino, which exceeded them in 50%.

show abstract

“…Since the 1990s, multiple observations indicated that ULF magnetic anomalies ( f < 1 Hz) could be observed prior to large earthquakes (EQs) with magnitude greater than 5.5 or so (Akinaga et al., 2001; Fraser‐Smith et al., 1990; Han et al., 2011, 2015; Hattori, 2004; Hayakawa et al., 1996, 2000, 2015; Hirano & Hattori, 2011; Ida et al., 2008; Kopytenko et al., 1993; Molchanov et al., 1992; Schekotov et al., 2015; Takla et al., 2018; Xu et al., 2013). Especially, it was also indicated by practical measurements that the vertical component of ULF magnetic signals tends to be disturbed locally prior to the main shocks of large EQs (Han et al., 2011, 2015; Hattori et al., 2004; Hayakawa et al., 1996; Xu et al., 2013).…”

Section: Introductionmentioning

confidence: 99%

“…The pre‐seismic anomalies are generally too weak to be recognized by simple examination of the raw data, so some elaborate data processing methods appear. The polarization analysis, in which three orthogonal geomagnetic field components were required to be simultaneously recorded, was brought up for this purpose and was proved to be quite useful for monitoring the crustal activities (Akinaga et al., 2001; Hattori et al., 2004; Hayakawa et al., 1996, 2000, 2015; Hirano & Hattori, 2011; Ida et al., 2008; Takla et al., 2018). In the method of polarization analysis, a parameter of the spectral density ratio S Z / S H called polarization ratio therein, played an important role in discriminating the seismic magnetic anomalies from other signals.…”

Section: Introductionmentioning

confidence: 99%

Study on the ULF Magnetic Field Generated by Earth Currents Relating to Large EQs

et al. 2021

View full text Add to dashboard Cite

ULF magnetic anomalies (f < 1 Hz) have been observed prior to multiple large earthquakes (EQs) during the last three decades. A polarization analysis method was produced and applied in many EQ cases in order to discriminate the weak ULF crustal signals from other signals. Although many publications considered the parameter of polarization ratio (amplitude or power ratio of vertical magnetic field component to horizontal components), a key parameter in the polarization analysis method, useful to detect the possible magnetic signals associated with EQs, there were also many doubts on its reliability. The aim of this work is to evaluate the possibilities of the polarization ratio increases prior to large EQs based on the prevail assumption of Earth currents as the source of ULF emissions during the early stage of EQ preparation independent of the mechanism involved in producing the currents, and the parallel 3‐D finite‐difference time‐domain technique is applied to calculate the electromagnetic responses in the whole inhomogeneous Earth‐ionosphere waveguide. The contributions of the lightning discharges on ULF power are also evaluated based on the gridded flash counts included in the Lightning Imaging Sensor climatology data. The results reveal that the surface vertical magnetic field and polarization ratio are possible to increase locally around the epicenters as long as the intensity of the surface seismic magnetic fields are large enough compared with those produced by other sources. Unfortunately, the actual increases are usually difficult to be distinguished obviously mostly due to the weak seismic increases.

show abstract

Anomalous ultra low frequency signals possibly linked with seismic activities in Sumatra, Indonesia

Cited by 7 publications

References 18 publications

Wavelet-based Characterization of Seismicity and Geomagnetic Disturbances in the South Sandwich Microplate Area

Wavelet-based Characterization of Seismicity and Geomagnetic Disturbances in the South Sandwich Microplate Area

Magnetogravimetric study on the Scotia Plate, in the South Atlantic Ocean for the characterization of tsunamis

Study on the ULF Magnetic Field Generated by Earth Currents Relating to Large EQs

Contact Info

Product

Resources

About