NIOM Analysis of Earthquake Observation Records in a Rockfill Dam

ABSTRACT We applied the normalized input–output minimization method (a method developed for the analysis of propagation times in vertical array records) to long-term earthquake observation records from Aratozawa Dam (in Kurihara, Miyagi prefecture, Japan), spanning the period from July 1992 to December 2019 to determine the propagation velocity of seismic waves in the embankment, and investigated changes in soil properties. As a result, we showed that (1) the velocities of S and P waves in the upper section were 449 and 993 m/s, respectively, prior to the strong earthquake motions derived from earthquake records from January 1997 through October 2001, whereas 608 and 1538, respectively, in the lower section, (2) in the Iwate–Miyagi Nairiku earthquake, the S-wave velocity in the upper section decreased to 158 m/s in the principal shock, and (3) in subsequent minor earthquakes the propagation velocity increased more or less in proportion with the logarithm of the number of elapsed days, requiring three years or longer to return to the initial value, (4) although similar changes were observed in the Great East Japan earthquake of 2011, the reduction in propagation velocity that remained after the principal shock was smaller than in the case of the Iwate–Miyagi Nairiku earthquake, and it was judged that there were no large effects on the dam body such as those that occurred in the Iwate–Miyagi Nairiku earthquake, and furthermore (5) in the principal shock of the Iwate–Miyagi Nairiku earthquake, the shear modulus in the upper part of the dam body decreased from 400 to 50 MPa (with a maximum shear strain of 10−3), resulting in more pronounced changes than in the lower section, whereas the damping ratio increased by at least 10% in the lower section during the principal shock of the Iwate–Miyagi Nairiku earthquake, resulting in much greater changes than in the upper section.

The Impact of the COVID-19 Pandemic on Suicide Rate Trends in the Tsunami-Disaster-Affected Area Following the Great East Japan Earthquake

Background: People who experienced the Great East Japan Earthquake (GEJE) were expected to have additional levels of psychological burden resulting from the stressful conditions imposed during the coronavirus disease 2019 (COVID-19) pandemic; consequently, suicide rates may increase. Aim: We aimed to carry out continuous monitoring of suicide rates in the affected area following the GEJE under COVID-19 pandemic conditions. Method: This descriptive study monitored the suicide rates of the coastal area of Miyagi Prefecture, where disaster-related mental health activities have been continuing following severe damage caused by the tsunami disaster. An exponential smoothing time-series analysis that converted suicide rates into a smooth trend was conducted. Results: Although the suicide rate in the affected area was higher than the national average in February 2020, it showed a declining trend during the COVID-19 pandemic, while showing an increase trend in the national and non-affected areas. Limitations: Uncertainty about the direct reasons for suicide and the short time-scale observation are the limitations of this study. Conclusion: Although the national suicide rate increased, this was not the case for the affected area. Our findings may provide important lessons for suicide prevention during the COVID-19 pandemic, which needs careful regional monitoring of the state of suicide and of high-risk approaches such as disaster-related mental health activities.

Utility of a new notation to visualize flow cytometry analysis results: first preliminary comparison with immunohistochemistry to detect CD30 expression on T-cell lymphoma cells

Background It is important to confirm CD30 expression in T-cell lymphoma cases, but immunohistochemical staining for CD30 is not commonly performed and no comparison has been done between the results of flow cytometry (FCM) and immunohistochemical staining for CD30. Therefore, we devised a notation that we termed proportion of immunoreactivity/expression for FCM (PRIME-F notation), based on the cellular proportion showing different antigen-antibody reactivity. Methods We retrospectively compiled 211 cases of T-cell lymphoma, assessed via FCM, from major hospitals in Miyagi Prefecture from January 2012 to January 2019, and compared 52 of these cases with the immunohistochemical immunoreactive (IR) pattern of CD30 (PRIME-I notation). The PRIME-F notation was divided into five levels: notations starting with “-” followed by 3, 2, and 1 “>” correspond to level-I, level-II, or level-III; notations starting with “(dim)+” correspond to level-IV; and those starting with “+” or “(bright)+” correspond to level-V. Results The 52 cases of PRIME-F notation with “+” included 16 cases of peripheral T-cell lymphoma (PTCL/NOS), 3 of follicular T-cell lymphoma (FTL), 3 of angioimmunoblastic T-cell lymphoma (AITL), 6 of extranodal NK/T-cell lymphoma/nasal type (ENKL), 18 of adult T-cell lymphoma (ATL), and 6 cases of anaplastic large cell lymphoma (ALCL). Eight of the 52 cases were immunohistochemically CD30-negative. In the PRIME-F level-I to III group (excluding false-positive cases), 21.7% (5 out of 23 cases) were < 10% positive for CD30 upon immunohistochemistry (IHC). Contrarily, in the level-IV & -V group, no CD30 positivity rate of < 10% upon IHC was found (0%) (p = 0.0497). In level-IV, 42.9% of cases presented a CD30 negative rate > 1/3 upon IHC, while in level-V, only 7.1% (one out of 14 cases) did. The CD30 negative rate tended to be low (p = 0.0877) in level-V. Conclusions To our knowledge, this is the first report describing the correspondence between FCM and immunohistochemistry findings for CD30 through newly proposed notations. The PRIME-F and PRIME-I notations for CD30 showed a minor positive correlation. The PRIME notation is considered universally applicable to antibodies, and notations of both FCM and IHC show great potential for big data.

Issues in Tsunami Countermeasures from the Viewpoint of Geotechnical Engineering

The 2011 off the Pacific coast of Tohoku Earthquake, with its epicenter off the Sanriku coast, measured the moment magnitude of 9.0, had a maximum seismic intensity of 7 in the northern part of Miyagi Prefecture, and impacted an area of 450 km. Consequently, a variety of unprecedented problems were made apparent. In particular, the human and property damage wrecked by the ensuing tsunami triggered our response for earthquake and tsunami resistance. In addition to conventional issues, such as earthquake resistance of buildings, disruption of lifelines, liquefaction of residential land and soil structures, and tsunami damage in coastal areas, there were new challenges, such as prolongation of earthquake disaster waste treatment. During the 10 years since the 2011 earthquake, tsunami countermeasures have been reexamined, and based on the concept of multiple protections, both tangible and intangible countermeasures have been advanced. This article addresses technical problems related to complex disasters, and includes the example of actual damage to a river levee in the Iwate Prefecture and the case of a building overturned by tsunami in Onagawa City, Miyagi Prefecture. It also discusses liquefaction caused by earthquakes and lists the points to be considered when selecting tsunami evacuation buildings to tackle future tsunami disasters.

Changes in the b value in and around the focal areas of the M6.9 and M6.8 earthquakes off the coast of Miyagi prefecture, Japan, in 2021

We investigated changes in the b value of the Gutenberg–Richter’s law in and around the focal areas of earthquakes on March 20 and on May 1, 2021, with magnitude (M) 6.9 and 6.8, respectively, which occurred off the Pacific coast of Miyagi prefecture, northeastern Japan. We showed that the b value in these focal areas had been noticeably small, especially within a few years before the occurrence of the M6.9 earthquake in its vicinity, indicating that differential stress had been high in the focal areas. The coseismic slip of the 2011 Tohoku earthquake seems to have stopped just short of the east side of the focus of the M6.9 earthquake. Furthermore, the afterslip of the 2011 Tohoku earthquake was relatively small in the focal areas of the M6.9 and M6.8 earthquakes, compared to the surrounding regions. In addition, the focus of the M6.9 earthquake was situated close to the border point where the interplate slip in the period from 2012 through 2021 has been considerably larger on the northern side than on the southern side. The high-stress state inferred by the b-value analysis is concordant with those characteristics of interplate slip events. We found that the M6.8 earthquake on May 1 occurred near an area where the b value remained small, even after the M6.9 quake. The ruptured areas by the two earthquakes now seem to almost coincide with the small-b-value region that had existed before their occurrence. The b value on the east side of the focal areas of the M6.9 and M6.8 earthquakes which corresponds to the eastern part of the source region of the 1978 off-Miyagi prefecture earthquake was consistently large, while the seismicity enhanced by the two earthquakes also shows a large b value, implying that stress in the region has not been very high.

809Sodium/potassium ratio change was associated with blood pressure change: finding from health check-up data

Background The sodium (Na)/potassium (K) ratio was reported to be associated with blood pressure (BP). Recently, the Na/K ratio self-monitoring device using spot urine was established. We assessed whether the urinary Na/K ratio change measured using the Na/K device was positively associated with BP change in a health check-up setting. Methods We targeted 12,890 participants who attended the annually health check-up in Tome City, Miyagi Prefecture, Japan between 2017 and 2018. Tome city introduced urinary Na/K ratio measurement during health check-up since 2017. We assessed the relationship between change in urinary Na/K ratio and BP change using multiple regression analyses adjusted for age, sex, and change in body mass index (BMI) and alcohol intake. For each year, we compared the baseline characteristics according to the urinary Na/K ratio and BP level. Results The change in systolic BP and diastolic BP was positively associated with the change in urinary Na/K ratio. The average urinary Na/K ratio was significantly lower in 2018 than in 2017 (5.4±3.0 to 4.9±2.2, p &lt; 0.01). Moreover, their systolic BP in 2018 (130.9±17.4 mmHg) was lower than that in 2017 (132.1±17.9 mmHg) (p &lt; 0.01). Conclusions The positive association of change in urinary Na/K ratio with hypertension and change in systolic and diastolic BP can be explained by a change in alcohol intake, BMI, and urinary Na/K ratio. Key messages Measuring the urinary Na/K ratio in community settings is a potential population approach for counteracting hypertension.

Coastal exposure and residents’ mental health in the affected areas by the 2011 Great East Japan Earthquake and Tsunami

No previous study has ever explored the association between coastal exposure and the mental health of residents in a post-disaster context. Therefore, we aimed to confirm whether there was an association between sea visibility and coastal proximity and the mental health of coastal residents a devastating tsunami. We targeted 15 coastal municipalities located in the Miyagi Prefecture, and obtained data from a community-based cohort study. The baseline survey was initiated 2 years after the 2011 Great East Japan Earthquake and Tsunami and the secondary survey was initiated 6 years after the disaster. We applied multilevel mixed-effects models to the longitudinal data. Our outcome measure was the Kessler Psychological Distress Scale (K6) score. We assessed the data collected from 2,327 respondents on both surveys as of April 2018 for this ongoing cohort study. We found that neither sea visibility nor coastal proximity was significantly associated with the recovery of mental health after the disaster. However, we found a distinctive trend of mental health recovery in people who lived alone with a sea view, indicating that visibility of the sea had a negative effect on their mental health immediately after the GEJET, but that the negative effect was subsequently eliminated.