BackgroundMothers of young children are at high-risk for developing adverse mental health effects following a nuclear accident. Using the Japanese pregnancy registration system, the prefecture of Fukushima launched a population-based survey of women who were pregnant at the time of the Fukushima nuclear accident in order to assess their and their newborns’ health. In this paper, we focus on the results of a screen for depressive symptoms among new mothers and its association with geographical region and interruption of obstetrical care after the Fukushima nuclear accident, which occurred after the Great East Japan Earthquake on March 11, 2011.MethodsThe survey targeted women who lived in Fukushima prefecture and who had registered their pregnancies between August 1, 2010 and July 31, 2011. Among the 16,001 women targeted, 9,321 returned the questionnaires (response proportion = 58.3%) and data from 8,196 women with singleton live births were analyzed. The main outcome measure was a standard two-item depression screen. Regional radiation levels were determined from the prefecture’s periodical reports, and interruption in obstetrical care after the Fukushima nuclear accident was determined from mothers’ individual responses to the questionnaire.ResultsAmong the 8,196 women, 2,262 (28%) screened positive for depressive symptoms. After adjusting for maternal and infant characteristics, both mothers in Soso, the region in which the nuclear power plant is located, and mothers that had changed obstetrical care facilities were significantly more likely to screen positive for depression. In contrast, mothers in Iwaki and Aizu, regions with relatively low radiation levels, were significantly less likely to screen positive for depression.ConclusionsOur findings suggest that improving mental health support for mothers with infants should be a high priority in the acute phase of nuclear disaster response. We further recommend that in the strategic provisioning of parental support, close attention should be paid to regional variations in negative mental health consequences, particularly to those who experienced an interruption in their obstetrical care.

We analyzed continuous GPS data from more than 20 sites in Asia, Australia and islands in Indian Ocean in order to detect crustal deformations associated with the Sumatra-Andaman earthquake of December 26, 2004. Coseismic steps can be recognized at sites about 3,000 km away from the epicenter such as Kunming in south China, Quezon in Philippines, and Diego Garcia Island in central Indian Ocean. The largest displacement of about 26 cm is found at Phuket in Thailand about 600 km away from the epicenter, about twice as large as that at Sampari, the nearest site in northern Sumatra. These observations suggest that as large slip as 14 m occurred beneath the Nicobar Islands. Large postseismic displacements are observed at Phuket and Sampari after the mainshock, but the former is three times larger than the latter. This suggests that the spatial distribution of afterslip is different from the coseismic slip distribution. The temporal variation of postseismic displacements can be explained by a logarithmic function derived from rate-state dependent friction law with short characteristic time. The area where coseismic displacements from the Nias earthquake of March 28, 2005 are detected is much smaller than that from the December mainshock, but displacement at Sampari is larger than that during the mainshock. These displacements suggest less than 4 m slip on a shallow dipping thrust fault and resultant moment release is smaller than that estimated from seismological data. Finally, total moment released by afterslip amounts to 3.83 × 10 22 Nm which is equivalent to Mw 8.99 for about five months, including the afterslip for the Nias earthquake.

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[1] Three boreholes with depths of 500, 800, and 1800 m were drilled near the Nojima fault, which is one of the 1995 HyogokenNanbu earthquake faults. In order to research the structure and its temporal change of the active fault, the water injection experiments were conducted from the 1800-m borehole in 1997 and 2000. Then, the discharge changes at the 800-m borehole were observed during the water injections. Considering the permeable zone near the fault as simple two-dimensional layer with an uniform thickness, we estimated the permeability of the permeable zone near the Nojima fault from the discharge changes associated with the water injections. It is found that the permeability of the permeable zone in 2000 became lower than that in 1997.

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