Generosity Betrayed

Between 1941 and 1945, Americans expressed outrage over Japan’s attack on Pearl Harbor and subsequent military aggression. Numerous commentators, citizens, and opinion-makers looked beyond wartime atrocities and regularly vilified Japanese for the crime of “ingratitude.” Japan, they argued, had not merely attacked the country that had opened it to the outside world a century earlier, but had also declared war on the people who had saved its citizens in 1923. This article explores why, amidst the great whirlwind of wartime inhumanity, Americans harkened back to their 1923 humanitarian engagement with Japan following the Great Kantō Earthquake. Many did so, I suggest, to assist wartime mobilization, to lionize America’s righteous global stature, and to forge and reinforce constructions of their enemy’s sub-human character. Only humans, many angry Americans argued, understood or could express feelings of gratitude. Highlighting Japan’s supposed “ingratitude,” and their “betrayal” of America’s humanitarian generosity served as an emotive way to dehumanize all Japanese beyond the well-documented discussions of wartime aggression, treachery, or “innate racial characteristics.” Elites employed these constructions drawn from their enemy’s supposed ingratitude to help legitimate a brutal war waged without mercy against soldiers and civilians alike.

Distribution of Holocene Marine Mud and Its Relation to Damage from the 1923 Earthquake Disaster in the Tokyo Metropolitan Area, Japan

Tokyo, which is located near the boundary between the North American and Philippine Sea plates, has been frequently struck by large earthquakes throughout the Holocene. The 1923 Taisho Kanto Earthquake is a rare historical earthquake that can be reconstructed in detail because abundant datasets were collected by investigations performed just after the earthquake. We examined 13,000 borehole logs from the Tokyo and Nakagawa lowlands to clarify the distribution and thickness of incised-valley fills and soft marine mud that had accumulated since the Last Glacial Maximum (LGM) on a grid with a resolution of 150 m × 150 m. We compared these datasets with the distribution of wooden house damage ratios caused by the Taisho Kanto Earthquake. Our results showed that the thickness of the soft mud, but not that of the incised-valley fills, was strongly correlated with the wooden house damage ratio. The mud content was >60%, water content was >30%, and S-wave velocity was ca. 100 m/s in the soft Holocene marine mud. The wooden house damage ratio was highest where the soft mud thickness was 20 m, because in those areas, both the soft mud and the wooden houses resonated with a natural period of ca. 1 s.

Pre- and Post-Tsunami Depth Changes of Submarine Topography for the Analysis of Submarine Landslide-Induced Tsunami: Proposal of Digitization Method and Application to the Case of the 1923 Great Kanto Earthquake Tsunamis

We first propose and examine a method for digitizing analog data of submarine topography by focusing on the seafloor survey records available in the literature to facilitate a detailed analysis of submarine landslides and landslide-induced tsunamis. Second, we apply this digitization method to the seafloor topographic changes recorded before and after the 1923 Great Kanto earthquake tsunami event and evaluate its effectiveness. Third, we discuss the coseismic large-scale seafloor deformation at the Sagami Bay and the mouth of the Tokyo Bay, Japan. The results confirmed that the latitude / longitude and water depth values recorded by the lead sounding measurement method can be approximately extracted from the sea depth coordinates by triangulation survey through the overlaying of the currently available GIS map data without geometric correction such as affine transformation. Further, this proposed method allows us to obtain mesh data of depth changes in the sea area by using the interpolation method based on the IDW (Inverse Distance Weighted) average method through its application to the case of the 1923 Great Kanto Earthquake. Finally, we analyzed and compared the submarine topography before and after the 1923 tsunami event and the current seabed topography. Consequently, we found that these large-scale depth changes correspond to the valley lines that flow down as the topography of the Sagami Bay and the Tokyo Bay mouth.

Multiple-channel Singular Spectrum Analysis-based noise reduction for MT data observed in Boso Peninsula, Japan

<p>Off the coast of the Boso Peninsula, there is a triple junction of the Pacific Plate, the Philippine Sea Plate, and the North American Plate and the Boso Peninsula is one of the seismically active areas in Japan. There are also epicenter areas such as the 1703 Genroku Kanto Earthquake (M8.2), the 1923 Taisho Kanto Earthquake (M7.9), and the Boso Slow Slip which occurs every 6 years, which are geologically interesting places. To estimate the subsurface resistivity structure of the whole Boso area, Magnetotelluric (MT) survey with 41 sites (inter-sites distance of 7 km) has been conducted in 2014-2016, using U43 (12 sites, 1 Hz sampling ; Tierra Technica) and MTU-5, 5A, net (41 sites, 15, 150, and 2400 Hz sampling; Phoenix Geophysics). However, the Boso area is greatly affected by leak current from DC-driven trains, factories, and power lines, so the observed data are contaminated by artificial noises. When we tried to apply the conventional noise reduction method (e.g., remote reference (Gamble et al., 1979) and BIRRP (Chave and Thomson, 2004)) in frequency domain, the obtained MT sounding curve was not ideal. In particular, the phase between the periods of 20 and 400 sec was close to 0 degrees. It suggests that the method used is insufficient to reduce the near-field effect for the Boso data. Thus, we developed a new noise reduction method using MSSA (Multi-channel Singular Spectrum Analysis) as a pre-processing method in time domain.</p><p>The procedure is as follows;</p><p>(1) Decompose 6 component data (Hx, Hy, Ex, Ey, Hxr and Hyr: H and E means magnetic and electric field, respectively, x and y indicates NS and EW component, and r denotes the reference field observed at a quiet station) using MSSA into 6×M principal components (PCs).  Here, M shows the window length of MSSA.</p><p>(2) Check contribution and periods of each PC and eliminate the PCs which are corresponding to the longer periods of variation. That is “detrend” of the original data.</p><p>(3) Apply the second MSSA to the detrended time series data to separate signals and noises shorter than 400 sec.</p><p>(4) Calculating correlation coefficients between H and Hr and between E and Hr for each PC and select the PCs with higher correlation to reconstruct time series data to make MT analysis.</p><p>Then, we perform MT analysis by BIRRP to estimate apparent resistivity,</p><p>As a result, the coherences of H-Hr, and E-Hr were improved and the MT sounding curve became smoother than those results by the conventional noise reduction methods. This indicated that the effectiveness of the proposed noise reduction. However, further investigation in different periods and sites will be required.</p>

Disaster Museums in Japan: Telling the Stories of Disasters Before and After 3.11

Japan has an established tradition of museums commemorating its long history of disasters, which memorialize lives lost and convey the scientific mechanisms of natural hazards, disaster history, and people’s experiences during and after disasters. The first part of this paper provides an overview of seven modern disaster museums in Japan established before 3.11, starting from the museum of the 1923 Great Kanto Earthquake. These seven museums commemorate disasters of different types, time, and scales of damages. Considering their shared commonalities and individual characteristics, it describes the components and approaches of exhibits that these museums use to convey experiences and stories of disasters, passing on local knowledge toward future disaster risk reduction. The second part of the paper provides an overview of new museums and exhibit facilities established to commemorate the 3.11 Great East Japan Earthquake, tsunami, and nuclear disaster of March 11, 2011. The scale of the devastation of 3.11, as well as an explosion of interest and support for activities of memorialization, documentation, and exhibition, has resulted in a variety and decentralization of new museums and exhibit spaces throughout the area affected by the 3.11 disaster. Spanning various combinations and types of exhibit facilities, this paper concludes by considering emergent trends compared to pre-3.11 disaster museums and potential future developments.