Emission of electromagnetic radiation preceding the Ito seismic swarm of 1989

Fujinawa, Yukio; Takahashi, Kozo

doi:10.1038/347376a0

Cited by 82 publications

(35 citation statements)

References 14 publications

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“…The system is very sensitive to crustal activities such as earthquakes and volcanic eruptions and is highly robust to both meteorological and urban noises. The evaluation of the system was based on observations at different geological situations at 13 sites in central Japan and for more than 13 years (e.g., [11,25,33]). …”

Section: Observation Methodsmentioning

confidence: 99%

Remote Detection of the Electric Field Change Induced at the Seismic Wave Front from the Start of Fault Rupturing

Fujinawa¹,

Takahashi²,

Noda³

et al. 2011

International Journal of Geophysics

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Seismic waves are generally observed through the measurement of undulating elastic ground motion. We report the remote detection of the Earth's electric field variations almost simultaneously with the start of fault rupturing at about 100 km from the fault region using a special electric measurement. The rare but repeated detection indicates that the phenomenon is real. The characteristic time of diffusion is almost instantaneous, that is, less than 1 second to travel 100 km, more than ten times faster than ordinary seismic P wave propagation. We suggest that the measured electric field changes are produced by the electrokinetic effect through increased pore water pressure of the seismic pulse. It is also suggested that the long range propagation is due to the surface wave mode confined near the interface of the different conductivity. The length scale of the finite strength of the electric field is 16 km, 160 km for electric conductivity of 0.01, 0.001, Sm −1 , respectively. This phenomenon suggests a new seismic sensing method and a new earthquake early warning system providing more seconds of lead time.

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Section: Observation Methodsmentioning

confidence: 99%

Remote Detection of the Electric Field Change Induced at the Seismic Wave Front from the Start of Fault Rupturing

Fujinawa¹,

Takahashi²,

Noda³

et al. 2011

International Journal of Geophysics

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“…Each corona discharge is accompanied by a light blip (which have also been recorded) and by RF noise. On a larger scale in earthquake zones, these may be related to the "earthquake lights" (Derr, 1973) and strong RF (KHz to MHz) noise detected (Fujinawa, 1990) prior to large earthquakes. (Freund, 2007a, b, c) showing positive currents after stress is applied.…”

Section: Air Ionizationmentioning

confidence: 99%

“…There have been many papers from the 1960's to present which reported electromagnetic signals prior to large earthquakes, These signals span the electromagnetic spectrum from slow moving DC magnetic field changes (Yen, 2004), ultra low frequency (ULF) magnetic field energy bursts (Fraser Smith, 2002;Molchanov, 2003Molchanov, , 2004, radio frequency signals from kHz to MHz (Fujinawa, 1990), infra red (IR) signatures (Ouzounov, 2007), visible earthquake lights (Derr, 1973), ionospheric disturbances (Pulinets, 2004;Molchanov, 2003Molchanov, , 2004Liu, 2001Liu, , 2004, and others. Most of these phenomena are difficult to monitor in both space and Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

Investigation of ULF magnetic pulsations, air conductivity changes, and infra red signatures associated with the 30 October Alum Rock M5.4 earthquake

Bleier

Dunson

Maniscalco

et al. 2009

Nat. Hazards Earth Syst. Sci.

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Abstract. Several electromagnetic signal types were observed prior to and immediately after 30 October 2007 (Local Time) M5.4 earthquake at Alum Rock, Ca with an epicenter ∼15 km NE of San Jose Ca. The area where this event occurred had been monitored since November 2005 by a QuakeFinder magnetometer site, unit 609, 2 km from the epicenter. This instrument is one of 53 stations of the QuakeFinder (QF) California Magnetometer NetworkCalMagNet. This station included an ultra low frequency (ULF) 3-axis induction magnetometer, a simple air conductivity sensor to measure relative airborne ion concentrations, and a geophone to identify the arrival of the P-wave from an earthquake. Similar in frequency content to the increased ULF activity reported two weeks prior to the Loma Prieta M7.0 quake in 1989 (Fraser-Smith, 1990, 1991, the QF station detected activity in the 0.01-12 Hz bands, but it consisted of an increasing number of short duration (1 to 30 s duration) pulsations. The pulsations peaked around 13 days prior to the event. The amplitudes of the pulses were strong, (3-20 nT), compared to the average ambient noise at the site, (10-250 pT), which included a component arising from the Bay Area Rapid Transit (BART) operations. The QF station also detected different pulse shapes, e.g. negative or positive only polarity, with some pulses including a combination of positive and negative. Typical pulse counts over the previous year ranged from 0-15 per day, while the count rose to 176 (east-west channel) on 17 October, 13 days prior to the quake. The air conductivity sensor saturated for over 14 h during the night and morning prior to the quake, which occurred at 20:29 LT. Anomalous IR signatures were also Correspondence to: T. Bleier (tbleier@quakefinder.com) observed in the general area, within 50 km of the epicenter, during the 2 weeks prior to the quake. These three simultaneous EM phenomena were compared with data collected over a 1-2-year period at the site. The data was also compared against accounts of air ionization reported to be associated with radon emission from the ground (Ouzounov, 2007), and a series of laboratory rock stressing experiments (Freund, 2006(Freund, , 2007a to determine if field data was consistent either of these accounts. We could not find a data set with preearthquake radon measurements taken near the Alum Rock epicenter to compare against our field data. However, based on the Alum Rock data set example and another data set at Parkfield, the field tests are at least consistent with the lab experiments showing currents, magnetic field disturbances, air conductivity changes, and IR signatures. This is encouraging, but more instrumented earthquake examples are needed to prove a repeating pattern for these types of pre-earthquake EM signatures.

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“…One is that the anomalous vertical electric field near the Earth's surface above the seismogenic zone will penetrate into the ionosphere, causing the irregularities of electron density by the ion drifting (Kelley 1989;Fujinawa and Takahashi 1990;Pulinets et al 2000). The other is that the atmospheric gravity waves (AGW) forced by earthquakes may propagate upward to perturb into the ionosphere (Weaver et al 1970;Hayakawa 1999;Liu et al 2008a).…”

Section: Discussionmentioning

confidence: 99%

Ionospheric Anomalies Observed by GPS TEC Prior to the Qinghai-Tibet Region Earthquakes

Xia¹,

Yang²,

Xu³

et al. 2011

Terr. Atmos. Ocean. Sci.

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The precursory processes detected from unambiguous and repeatable instrumental observations that precede an earthquake remain elusive despite the multiple types of pre-earthquake signals gained from observations of geo-electricity, geomagnetism, and electromagnetism. Recently, much attention has been paid to associate abnormal behaviors of TEC (total electron content) in ionosphere, with seismic forcing. In this paper, we examined ionospheric TEC variations 1 -2 weeks preceding 20 moderate to great earthquakes (M = 5 -8) in the Tibetan Plateau and its neighboring regions between 1999 to 2008, with the help of a nationwide continuously-tracking GPS network. The temporal and spatial TEC variations over the specific seismogenic zones were calculated, and the causal linkage between the identified TEC anomalies and these earthquakes was examined. We find that most of the earthquakes showed significant abnormalities with similar characteristics. The anomalies, either upper anomalies (85%, 17/20) or lower anomalies (65%, 13/20) occurred in the ionosphere with dimensions of 30° in latitude and 30° in longitude above the epicenters. It is noted that the ionospheric anomalies were more dependent on focal depths of earthquakes than their magnitudes. Our results suggest that these anomalies of TEC may be possible seismoionospheric signatures for the earthquakes in Tibet and its margins.

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Emission of electromagnetic radiation preceding the Ito seismic swarm of 1989

Cited by 82 publications

References 14 publications

Remote Detection of the Electric Field Change Induced at the Seismic Wave Front from the Start of Fault Rupturing

Remote Detection of the Electric Field Change Induced at the Seismic Wave Front from the Start of Fault Rupturing

Investigation of ULF magnetic pulsations, air conductivity changes, and infra red signatures associated with the 30 October Alum Rock M5.4 earthquake

Ionospheric Anomalies Observed by GPS TEC Prior to the Qinghai-Tibet Region Earthquakes

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