The Japan earthquake of March 11th, 2011 (Mw = 8.9R) as viewed in terms of local lithospheric oscillation due to M1 and K1 tidal components. A brief presentation

Thanassoulas1, C., Klentos2, V., Verveniotis, G.3, Zymaris, N.4

1. Retired from the Institute for Geology and Mineral Exploration (IGME), Geophysical Department, Athens, Greece. e-mail: thandin@otenet.gr - URL: www.earthquakeprediction.gr

2. Athens Water Supply & Sewerage Company (EYDAP), e-mail: klenvas@mycosmos.gr - URL: www.earthquakeprediction.gr

3. Ass. Director, Physics Teacher at 2 nd Senior High School of Pyrgos, Greece. e-mail: gver36@otenet.gr - URL: www.earthquakeprediction.gr

4. Retired, Electronic Engineer.

Abstract

The time of occurrence of the large EQ that occurred recently in Japan (March 11 th, 2011, Mw = 8.9) is compared to the time of peak amplitude occurrence of the M1 and K1 tidal components. It is shown that the specific EQ occurred on the peak of the M1 tidal component, and deviates for only 45 minutes from the corresponding K1 tidal peak. Therefore, the specific seismic event complies quite well with the earlier proposed physical mechanism (lithospheric oscillation) that causes triggering of large EQs.

Key words: Japan, large earthquakes, M1 tidal wave, K1 tidal wave, lithospheric oscillations, tidal oscillations short-term earthquake prediction.

1. Introduction.

The aim of this very brief presentation is to show that the M1 and K1 tidal components play an important role concerning the time of occurrence of a large EQ. Actually, they provide the last decisive bit of stress load required in order to trigger a large EQ at an already critically stress charged seismogenic area. The physical mechanism that holds for the EQ triggering by the tidal waves has been presented in detail by Thanassoulas (2007) while specific examples have been presented from the Greek seismogenic area by Thanassoulas (2007), Thanassoulas and Klentos (2010), Thanassoulas et al. (2011) and from New Zealand (Thanassoulas et al. 2011). In this brief presentation the time of occurrence of the very large EQ (Mw = 8.9) that occurred on 11 th of March, 2011 in Japan will be compared to the local seismogenic area tidal conditions within a time window of some days before and after the EQ occurrence time. The tidal data have been determined by the Rudman et al. (1977) method.

2. The large EQ (Mw = 8.9R) of Japan of the 11th of March, 2011.

The location of the large EQ is shown in the following figure (1) as presented by the EMSC.

Fig. 1. Location (red star) of the large EQ (Mw = 8.9) of the 11 th of March, 2011 in Japan.

2 The corresponding M1 (T = 14 days) component tidal data.

The M1 tidal oscillating component will be compared to the time of occurrence of the corresponding large EQ. The comparison is presented in the following figure (2).

Fig. 2. Comparison of the M1 tidal oscillation (black line, the lithosphere is forced to oscillate in the same mode) with the time of occurrence (red bar) of the EQ of 11th of March, 2011 (Mw = 8.9). Vertical scale is in mgals.

In this case the EQ occurred, compared to the lithospheric tidal oscillation, exactly on the peak day of the M1 tidal wave

The corresponding K1 (T = 24 hours) tidal data.

Next, the lithospheric oscillating K1 component will be compared to the time of occurrence of the corresponding large EQ. The comparison is presented in the following figure (3).

Fig. 3. Comparison of the K1 tidal oscillation (black line, the lithosphere is forced to oscillate in the same mode) with the time of occurrence (red bar) of the EQ of the 11th of March, 2011 (Mw = 8.9). Vertical scale is in mgals.

The specific EQ deviated for only forty five (45) minutes from the corresponding lithospheric oscillating tidal peak of the K1 component.

3. Conclusions.

The inspection of figures (2) and (3) shows that:

a) the recent large EQ (Mw = 8.9) of Japan occurred on the 11 th of March of 2011 when the tidal component of M1 achieves an oscillation amplitude peak (minimum) and consequently, the corresponding seismogenic area reaches a maximum of stress load on this specific day. Therefore the deviation (dt) of the time of the EQ occurrence from the M1 tidal peak time is null.
dt = 0 days in terms of M1 tidal component.

b) the recent large EQ (Mw = 8.9) of Japan occurred on the 11 th of March of 2011 and closely when the tidal component of K1 achieves a daily oscillation amplitude peak (maximum) and consequently the corresponding seismogenic area reaches a same day short-term maximum of stress load. The deviation (dt) of the time of the EQ occurrence from the tidal peak time is determined from figure (3) as dt = 45 minutes from the K1 tidal peak time.

dt = 45 minutes in terms of K1 tidal component.

Consequently, the large EQ of Japan that occurred on 11 th