This Rapid Response Research Grant (RAPID) award is for the collection of ephemeral data from the March 11, 2011 Japanese earthquake and tsunami. Data will be collected from locations in Japan and the US Commonwealth of the Northern Mariana Islands. The PI and colleagues had visited the area following the 11 March 2011 Tohoku tsunami and recorded runup and tsunami currents. They also took soil and water samples for determination of concentrations of radioactive isotopes of Iodine and Cesium. A few of these samples suggested concentrations one order of magnitude higher than reported by others. In this project, additional data on tsunami runup will be obtained from Saipan, Tinian and Rota. Eyewitnesses to the tsunami will be contacted for additional information. Topsoil samples will be also obtained from the same sites previously sampled in Japan to validate the original findings.
The data collected on tsunami runup will help to complete existing databases on runup measurements from the Tohoku tsunami. These data can be used to validate tsunami inundation maps produced by NOAA for the Northern Mariana Islands. The data on concentrations of radioactive Cesium will help determine the magnitude and areal dispersion of radioactive elements released from the damaged nuclear power plants in Japan.
This RAPID was triggered by measurements made on a handful of soil samples collected in another NSF project surveying the impact of the 2011 Japan tsunami. These few samples showed activity concentrations over two orders of magnitude in some locations, than those widely believed from the fallout of the Fukushima accident. In this research grant, surface sediment (topsoil) from Miyagi and Iwate prefecture were collected by means of a scoop (0-5cm depth) and a few water samples as well. One criterion for first sample collection was the locales where the dose rate was at least three times higher than ambient radiation, measured with a hand-held radiation monitor (Geiger-Muller). The soil samples were analyzed by the radiology laboratory of the Hellenic Commission of Nuclear Energy (HCNR) and by the Technical University of Crete using gamma spectroscopiy with high purity (HP) Germanium (Ge) detectors of 70% relative efficiency placed into a lead shielding of 10cm thickness. The first sampling campaign led to another two campaigns, and a total of about 200 samples were analyzed for actitivty concentrations of radionucleides. The highest activity concentrations were for I131 was 1755Bq/kg, for Cs134 38430Bq/kg, for Cs135 1450Bq/kg and, for Cs137, the highest concentration was 43730Bq/kg. For comparison, in Japan, the highest activities in the soil "prescribed" under the Food Sanitation Law is 5000Bq/kg for Cs134 and for Cs137. The 2011 Fukushima accident will likely change the culture of the nuclear industry worldwide. By underscoring the unpredictability of the fallout, we demonstrated that it is not always easy to assess the effects of a nuclear accident, even post facto, adding impetus to the enhanced awareness of regulatory bodies and the industry in enforcing safety standards, particularly for tsunami attack.
