Journal of Geophysical Research: Space Physics
Supporting Information for
Are there new findings in the search for ULF magnetic precursors to
earthquakes?
F. Masci1, J. N. Thomas2, 3, 4
Nazionale di Geofisica e Vulcanologia, L’Aquila, Italy
Research Associates, Redmond, Washington, USA
3Department of Electrical and Computer Engineering, DigiPen Institute of Technology, Redmond, Washington, USA
4Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
1Istituto
2NorthWest
Contents of this file
Text S1.
Figures S1 to S3.
Tables T1 to T2.
Introduction
In Figures 3 and 4 we have compared the amplitude of the geomagnetic field components (HPc3,
DPc3, and ZPc3) and the ZPc3/HPc3 reported by Takla et al. [2012] at the time of the 2007-2008 Peru
earthquakes with the Kp index. The supporting information includes additional comparisons with
the Dst index (Figure S1) and the solar wind speed (Figure S2). In Text S1 we report a brief
comment on the recent report by Schekotov and Hayakawa [2015]. The Auxiliary Material also
includes two tables.
1
Figure S1. The amplitude of the Pc3 geomagnetic field components and the ZPc3/HPc3 ratio as
reported by Takla et al. [2012] at the time of the 2007-2008 Peru earthquakes compared with the
Dst index time-series.
2
Figure S2. The amplitude of the Pc3 geomagnetic field components and the ZPc3/HPc3 ratio as
reported by Takla et al. [2012] at the time of the 2007-2008 Peru earthquakes compared with the
solar wind speed time-series.
3
Text S1. The report by Currie and Waters [2014] motivated Schekotov and Hayakawa [2015] to
perform retrospective investigations of ULF magnetic data searching for possible precursors of the
11 March 2011 Mw9 Tohoku-Oki earthquake in polarization ratio time series. Schekotov and
Hayakawa [2015] analyzed nighttime (01:00-05:00 JST) magnetic records from the Japanese
observatories of Memambetsu, Kakioka, and Kanoya that are away from the earthquake epicenter
640 km, 300 km, and 1300 km respectively. See Figure 1 by Schekotov and Hayakawa [2015] for
the location of the magnetic observatories. They claim to have found reasonable results just in
magnetic records from Kanoya, the farthest station from the Tohoku-Oki earthquake epicenter. The
magnetic polarization ratio Pzz/Phh (or impendence ratio according to their new definition) at
Kanoya shows increases during the months before the earthquake that Schekotov and Hayakawa
[2015] suggest are seismogenic. Pzz and Phh are the integrated powers of the vertical and the
horizontal components of the geomagnetic field in the frequency range 10-150 mHz. In Figure S3
we show the ratio Pzz/Phh as reported by Schekotov and Hayakawa [2015].
We would like to point out that Schekotov and Hayakawa [2015] is yet another paper where
the authors refer to reports of invalid ULF precursors (see, e.g., Hayakawa et al. [1996]). They also
ignore recent papers where it is shown that many reported preearthquake magnetic polarization
ratio anomalies are not actual precursors.
Our major comments can be summarized as follow:
i. According to Schekotov and Hayakawa [2015] the increase of the ratio Pzz/Phh is due to a
prevailing increase of the amplitude of Pzz. They note that at Kanoya Pzz shows a seasonal
variation with winter maxima and a stronger increase during the winter just before the
earthquake. Since Pzz seems to be anti-correlated with the monthly mean of atmospheric
pressure, temperature, and humidity (see their Figures 9 and 10), they exclude that the behavior
of Pzz is related to electromagnetic disturbances from the Earth’s lithosphere suggesting
atmospheric discharges as possible sources for ULF signals. However, Schekotov and
Hayakawa [2015] claim that during the winter 2010-2011, just before the earthquake, Pzz and
Pzz/Phh show a stronger increase caused by air ionization due to an alleged injection of gas
(radon?) from the focal zone of the pending earthquake.
In our opinion, if gas injections actually occurred before the Tohoku-Oki earthquake, we
would have to observe their possible influence in magnetic records from Kakioka, which is the
closest station to the earthquake epicenter, and not just at Kanoya, which is more than 1000 km
from the epicenter. Figures 8 and 9 by Schekotov and Hayakawa [2015] show that at Kakioka
Pzz maxima occur during winter months (usually in January). The only difference is that Pzz
shows a higher maximum during the winter 2010-2011, but this does not necessarily mean that
it is of seismogenic origin.
ii. The authors, by means of the Dst index, perform an insufficiently rigorous check of the
geomagnetic conditions at the time of the Tohoku-Oki earthquake. In Figure S3 we have
superimposed the global geomagnetic ΣKp index onto the Pzz/Phh time series. As expected
there is a close correspondence between the ratio Pzz/Phh and Kp both before and after the
earthquake (refer also to section 3.1). This demonstrates that at Kakioka the seasonal variation
of Pzz/Phh is driven by global geomagnetic activity changes.
iii. Utada et al. [2011] investigated magnetic data from 14 Japanese magnetic stations (which
include Memambetsu, Kakioka, and Kanoya) at the time of the Tohoku-Oki earthquake. Even
if they have observed coseismic and postseismic geomagnetic disturbances in response to the
earthquake and the generated tsunami, they did not found any actual precursors. Note that the
analysis of Schekotov and Hayakawa [2015] does not show any coseismic effect.
4
In summary, it is evident that the increase of the ratio Pzz/Phh reported by Schekotov and
Hayakawa [2015] during the first months of 2011 is not of seismogenic origin, but, indeed, is part
of global magnetic-field changes (see Figure S3). By renaming the polarization ratio impendence
ratio, Schekotov and Hayakawa [2015] failed to increase its reliability as an indicator of precursory
effects in ULF magnetic data.
Figure S3. A partial reproduction of Figure 8 by Schekotov and Hayakawa [2015]. (a)
Geomagnetic Dst index and seismicity Kls index. According to the authors, Kls is an index of local
seismicity as function of the distance from the earthquake epicenter and the earthquake magnitude.
See Schekotov and Hayakawa [2015] for details. (b) 10-day average of Pzz/Phh at Kanoya
observatory. The 10-day average of the global geomagnetic ΣKp index during 2010-2012 is
superposed onto the original view.
References:
Currie, J. L., and C. L. Waters (2014), On the use of geomagnetic indices and ULF waves for
earthquake precursor signatures, Geophys. Res. Space Physics, 119, 992–1003, doi:
10.1002/2013JA01953.
Schekotov, A., and M. Hayakawa (2015), Seismo-meteo-electromagnetic phenomena observed
during a 5-year interval around the 2011 Tohoku earthquake, J. Phys. Chem. Earth, in press,
http://dx.doi.org/10.1016/j.pce.2015.01.010.
Takla, E.M., K. Yumoto, J. Ishitsuka, D. Rosales, S. Dutra, T. Uozumi, and T. Abe (2012),
Geomagnetic variations possibly associated with the Pisco earthquake on 15 August 2007, Peru,
Tectonophysics, 524–525, 29–36. doi:10.1016/j.tecto.2011.12.008.
Utada, H., H. Shimizu, T. Ogawa, T. Maeda, T. Furumura, T. Yamamoto, N. Yamazaki, Y.
Yoshitake, and S. Nagamachi (2011), Geomagnetic field changes in response to the 2011 off the
Pacific Coast of Tohoku earthquake and tsunami, Earth Planet. Sci. Lett., 311, 11–27,
doi:10.1016/j.epsl.2011.09.036.
5
Table S1. Papers where the alleged ULF precursors highlighted in Figure 1 by red dots have been denied.
Earthquake
Reviews
Loma Prieta EQ 17-10-1989
Campbell, W. H. (2009), Natural magnetic disturbance fields, not precursors, preceding the Loma Prieta earthquake, J. Geophys. Res., 114, A05307,
doi:10.1029/2008JA013932.*
Thomas, J. N., Love, J. J, Johnston, M. J. S.: On the reported magnetic precursor of the 1989 Loma Prieta earthquakes, Phys. Earth Planet. Int., 173, 207-215,
doi:10.1016/j.pepi.2008.11.014, 2009.
Guam EQ 08-08-1993
Thomas, J. N., Love, J. J, Johnston, M. J. S., Yumoto, K.: On the reported magnetic precursor of the 1993 Guam earthquake, Geophys. Res. Lett., 36, L16301,
doi:10.1029/2009GL039020, 2009.
Masci, F.: On claimed ULF seismogenic fractal signatures in the geomagnetic field, J. Geophys. Res., A10236,115, doi:10.1029/2010JA015311, 2010.
Masci, F.: On the seismogenic increase of the ratio of the ULF geomagnetic field components. Phys. Earth Planet. Int., 187, 19-32, doi:10.1016/j.pepi.2011.05.001, 2011.
Masci, F.: Brief communication “On the recent reaffirmation of ULF magnetic earthquakes precursors”, Nat. Hazards Earth Syst. Sci., 11, 2193–2198, doi:10.5194/nhess-112193-2011, 2011.
Masci, F.: On the multi-fractal characteristics of the ULF geomagnetic field before the 1993 Guam earthquake, Nat. Hazards Earth Syst. Sci., 13, 187–191, doi:10.5194/nhess-13187-2013, 2013.
Biak EQ 17-02-1996
Masci, F.: On claimed ULF seismogenic fractal signatures in the geomagnetic field, J. Geophys. Res., A10236,115, doi:10.1029/2010JA015311, 2010.
Masci, F.: 2011, On the seismogenic increase of the ratio of the ULF geomagnetic field components. Phys. Earth Planet. Int., 187, 19-32, doi:10.1016/j.pepi.2011.05.001, 2011.
Kagoshima EQs
03-26-1997, 05-13-1997
Masci, F.: 2011, On the seismogenic increase of the ratio of the ULF geomagnetic field components. Phys. Earth Planet. Int., 187, 19-32, doi:10.1016/j.pepi.2011.05.001, 2011.
Iwate EQ 03-09-1998
Masci, F.: 2011, On the seismogenic increase of the ratio of the ULF geomagnetic field components. Phys. Earth Planet. Int., 187, 19-32, doi:10.1016/j.pepi.2011.05.001, 2011.
Izu Swarm April-May 1998
Masci, F.: 2011, On the seismogenic increase of the ratio of the ULF geomagnetic field components. Phys. Earth Planet. Int., 187, 19-32, doi:10.1016/j.pepi.2011.05.001, 2011.
Chi-Chi EQ 21-09-1999
Masci, F.: 2011, On the seismogenic increase of the ratio of the ULF geomagnetic field components. Phys. Earth Planet. Int., 187, 19-32, doi:10.1016/j.pepi.2011.05.001, 2011.
Izu Swarm June-August 2000
Masci, F.: 2011, On the seismogenic increase of the ratio of the ULF geomagnetic field components. Phys. Earth Planet. Int., 187, 19-32, doi:10.1016/j.pepi.2011.05.001, 2011.
Masci, F., and J.N., Thomas: On the relation between the seismic activity and the Hurst exponent of the geomagnetic field at the time of the 2000 Izu swarm, Nat. Hazards Earth
Syst. Sci., doi:10.5194/nhess-13-2189-2013, 2013.
Miyagi EQ 13-06-2008
Masci, F: On the ULF magnetic ratio increase before the 2008 Iwate–Miyagi Nairiku earthquake by Hirano and Hattori (2011), J. Asian Earth Sci., 56, 258–262,
doi:10.1016/j.jseaes.2012.06.009, 2012.
Tasikmalaya EQ 02-09-2009
Masci, F. , Thomas J.N.: Comment on “Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet
transform and detrended fluctuation analysis”, by Febriani et al. (2014), under review, Nat. Hazards Earth Syst. Sci., 2015.
* Reply: Fraser‐Smith et al., (2011), Comment on “Natural magnetic disturbance fields, not precursors, preceding the Loma Prieta earthquake” by Wallace H. Campbell, J. Geophys. Res., 116, A08228,
doi:10.1029/2010JA016379.
6
Table S2. Papers cited by Han et al. [2014] that have reported invalid ULF magnetic precursors.
References in Han et al. [2014]
Earthquake
Reviews
Fraser-Smith et al., 1990, doi:10.1029/GL017i009p01465
1989 Loma Prieta
Campbell, 2009, doi:10.1029/2008JA013932 *
Thomas et al., 2009a, doi:10.1016/j.pepi.2008.11.014
Hattori, 2004.
1998 Iwateken Nairiku Hokubu
1997 Kagoshimaken-Hokuseibu
Masci, 2011a, doi:10.1016/j.pepi.2011.05.001
Hattori et al., 2004, doi: 10.1016/j.pce.2003.09.019.
1998 Iwateken Nairiku Hokubu
Masci, 2011a, doi:10.1016/j.pepi.2011.05.001
Hayakawa et al., 1996, doi:10.1029/95GL02863.
1993 Guam
Masci, 2011a, doi:10.1016/j.pepi.2011.05.001
Thomas et al . 2009b, doi:1029/2009GL039020
Hirano and Hattori, 2011, d oi:10.1016/j.jseaes.2010.04.038.
2008 Iwate–Miyagi Nairiku
Masci, 2012c, doi:10.1016/j.jseaes.2012.06.009.
Kon et al., 2011, doi:10.1016/j.jseaes.2010.10.005.
1998-2010 Japan M>6 EQs
Masci, 2012d, doi:10.1016/j.jseaes.2012.06.009
* Reply: Fraser‐Smith et al., (2011), Comment on “Natural magnetic disturbance fields, not precursors, preceding the Loma Prieta earthquake” by Wallace H.
Campbell, J. Geophys. Res., 116, A08228, doi:10.1029/2010JA016379.
7