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Data-driven machine-learning approaches are being increasingly applied to construct empirical ground-motion models (GMMs). It is a standard practice to divide observational records into learning and test datasets to correctly evaluate the predictive performance of a developed model. However, in this study, we show that division based on records or earthquakes is inappropriate for evaluating the generalization performance on recorded sites when GMMs include site-condition proxies as input variables. Complex models exhibit small residuals at sites used in the training process, but exhibit large residuals at new sites owing to overfitting to the trained sites. As a simple solution, we propose a neural network model that has monotonic dependence on some of the input variables. The model successfully obtains the generalization performance on recorded sites, although it lacks ability to represent oversaturation with input variables suggested in extreme ground-motion ranges. Therefore, alternative methods should be investigated to develop robust data-driven models under general conditions. Dividing the sites into learning and test data would play a fundamental role in developing such robust models.

A large-scale permanent ocean-bottom seismograph network, named S-net, has been established in the Japan Trench area and consists of 150 observatories equipped with seismometers and tsunamimeters. Most stations at water depths

Choosing the method for inputting site conditions is critical in reducing the uncertainty of empirical ground-motion models (GMMs). We apply a neural network (NN) to construct a GMM of peak ground acceleration that extracts site properties from ground-motion data instead of referring to ground condition variables given for each site. A key structure of the model is one-hot representations of the site ID, that is, specifying the collection site of each ground-motion record by preparing input variables corresponding to all observation sites. This representation makes the best use of the flexibility of NN to obtain site-specific properties while avoiding overfitting at sites where a small number of strong motions have been recorded. The proposed model exhibits accurate and robust estimations among several compared models in different aspects, including data-poor sites and strong motions from large earthquakes. This model is expected to derive a single-station sigma that evaluates the residual uncertainty under the specification of estimation sites. The proposed NN structure of one-hot representations would serve as a standard ingredient for constructing site-specific GMMs in general regions.

The 11 March 2011 Tohoku earthquake was the largest seismic event in the history of Japan. Potential mega‐earthquakes were not included in the National Seismic‐Hazard Maps for Japan (NSHMJ) because of the lack of information regarding very infrequent disastrous earthquakes that had occurred before no historical earthquakes were recorded. These earthquakes were not included in the conventional seismic activity model used to assess the probabilistic seismic‐hazard maps (PSHM); however, we recognize that it is essential for the probabilistic seismic‐hazard assessment to consider earthquakes that have a very low probability of occurrence. In order to improve the PSHM, we reconstructed the seismic activity model by (1) revising the long‐term evaluation of magnitude and occurrence probability for large earthquakes; (2) resetting the maximum magnitude of background earthquakes; (3) introducing large area sources to model the background seismicity model for crustal earthquakes; (4) modeling outer‐rise earthquakes; (5) revising the model for large earthquakes in the eastern margin of the Japan sea; and (6) developing new earthquake models for major active faults. Applying these improvements, the revised version of the NSHMJ was published in December 2014 by the Earthquake Research Committee of Japan.

The 3D wave propagation simulation is suitable for the long‐period ground‐motion hazard analysis, because the realistic seismic source and velocity structure models are applicable and ground motion at any point can be obtained. However, large‐scale simulations for various scenarios are needed to adopt uncertainty due to the source model of a large earthquake. Here we show our approach to overcome a problem of heavy computational expense. We improve computation performance of the 3D finite‐difference method by using discontinuous grids and by adapting to multigraphics processing units technique. Then, we simulate long‐period ground motion of many scenarios of a hypothetical megathrust earthquake in the Nankai trough. We use the characterized source models based on the “recipe” in the simulation. Finally, we apply the simulation results based on about 400 scenarios to a technical framework of the probabilistic seismic‐hazard analysis. The hazard maps of velocity response spectra for a given conditional exceedance probability show that the long‐period ground motion is more significant with respect to the underground structure than is the distance from the source area.

We analyzed strong-motion and broadband recordings of two moderate-magnitude earthquakes that occurred in the Nankai Trough. The first event was the 2004 Mw 6.5 southeast off-Kii peninsula earthquake, an aftershock event inside the Philippine Sea Plate near the Nankai Trough axis. The second event was the 2016 Mw 5.8 southeast off-Mie Prefecture earthquake, an independent event in the rupture area of the 1944 Mw ~ 8 Tonankai earthquake. The centroid depths were 11 and 14 km for the 2004 and 2016 events, respectively. Despite a large difference in the moment magnitude between the two events, the JMA magnitude (Mj) was 6.5 for both the events. We found that the short-period ground motions (e.g., response spectra at periods 20 s) for the 2016 event scaled generally well with the moment magnitude of the event. In contrast, the ground motions from the 2016 event were comparable to those for the larger-moment-magnitude 2004 event at equal distances at periods of about 2–20 s in wide areas and the observed acceleration response spectra at those periods were noticeably underestimated for the 2016 event by the ground motion prediction equation (GMPE) that employs Mw. An examination of the existing subsurface velocity model suggested that the difference in the relative location of the two events with respect to the thick accretionary prism of low seismic velocity most probably caused the comparable amplitude of the seismic waves at those periods. As a result, we posit that the values of Mj are equal for the two events because Mj is estimated using the displacement amplitude of ground motions at periods smaller than about 6 s. On the other hand, GMPE employing Mj generally described the observed data well. The results suggested that the plate boundary earthquakes in the Nankai Trough may excite strong long-period ground motions of engineering importance, and these ground motions appear to be better explained by Mj than by Mw in GMPEs for moderate-magnitude earthquakes in the Nankai Trough subduction zone.

The effects of the short-wavelength heterogeneity of the crustal structure on predicted ground motion at periods of 1 s and longer were investigated by conducting three-dimensional finite-difference simulations using a detailed realistic velocity model of the Kanto region of Japan. The short-wavelength heterogeneity of the media within the upper crust was randomly modeled using the exponential-type autocorrelation function where the velocity standard deviation was set to 5%. Combinations of heterogeneous media with various correlation lengths and point source models with various depths and durations were considered in order to investigate the variability of the predicted ground motion and the sensitivity to the parameters. The effects of random heterogeneity on the simulated ground motion appeared as a result of changes in the amplitude and phase of both the direct waves and later phases, as well as the spectral peaks of the response spectra. Ground-motion variability, in terms of peak ground velocity (PGV) and velocity response spectra (Sv), was evaluated using the residual, or the difference in logarithm of PGV and Sv between the ground motion computed with and without random heterogeneity. While the residual averaged over the surface of the computed area was almost negligible in the studied period range, the variability of the residual was found to increase with distance and to be larger for point sources with shorter durations.

We evaluated long-period ground motions for the anticipated Nankai Trough megathrust earthquake in southwest Japan. To understand a variation of longperiod ground motions caused by the uncertainty of the source model, we performed a finite difference simulation using 104 source models, assuming various possible source parameters, including rupture area, asperity configuration, and hypocenter location. For the variety of rupture areas, we included scenarios that have extremely huge rupture areas, as was proposed by the Japan Central Disaster Management Council of Cabinet Office after the 2011 Tohoku-Oki earthquake. We also included scenarios that have large slip areas near the trough following the lessons learned from the 2011 event. Simulated waveforms and response spectra show a large variation at a site. However, by grouping the simulation results with respect to the source area, we determined that scenarios with wider rupture areas have a larger peak ground velocity and velocity response than those with smaller rupture areas. The influence of the large slip near the trough causes later phases to be large and long. However, the later phases are decreased by using a boxcarlike slip velocity time function instead of a Kostrovlike function and by decreasing rupture velocity. The spatial distribution of the simulated peak ground velocity and velocity response show that the long-period ground motions are amplified particularly on sedimentary basins, where big cities have been established. It is important to consider how to account for the large variation of the simulation results in the seismic hazard assessment.

With the aim of better understanding and more effective utilization of probabilistic seismic hazard maps in Japan, exposure analysis has been carried out by combining hazard maps with population distribution maps. Approximately 80% of the population of Japan is exposed to a relatively high seismic hazard, i.e., a 3% probability of exceeding JMAseismic intensity 6 lower within 30 years. In highly populated areas, specifically in major metropolitan areas, seismic hazard tends to relatively high because of the site amplification effects of holocene deposits. In implementing earthquake disaster mitigation measures, it is important to consider the overlapping effect of seismic hazard and demographic distributions.

Under the guidance of the Headquarters for Earthquake Research Promotion of Japan, we have been carrying out seismic hazard assessment for Japan since the 1995 Hyogo-ken Nanbu Earthquake and have made the National Seismic Hazard Maps for Japan to estimate strong motion caused by earthquakes that could occur in Japan in the future, and show estimated results on these maps. The Hazard Maps consist of two kinds of maps. One kind is a probabilistic seismic hazard map that shows the relation between seismic intensity value and its probability of exceedance within a certain period. The other kind is a scenario earthquake shaking map. In order to promote the use of the National Seismic Hazard Maps, we have developed an open Web system to provide information interactively, and have named this system the Japan Seismic Hazard Information Station (J-SHIS). The 2011 Tohoku Earthquake (Mw9.0) was the largest such event in the recorded history of Japan. This megathrust earthquake was not considered in the National Seismic Hazard Maps for Japan. Based on lessons learned from this earthquake disaster and on experience we have had in the seismic hazardmapping project of Japan, we consider problems and issues to be resolved for seismic hazard assessment and make proposals to improve seismic hazard assessment for Japan.

In this study we suggest a new ground motion prediction equation applicable up to the moment magnitude 9 using the strong motion records from the 2011 Tohoku-oki earthquake. We determined a base model with moment magnitude and the shortest distance from the source fault as parameters. In order to avoid overestimating amplitude atmagnitude larger than 8, we examined two models – a quadratic magnitude term and a linear magnitude term with a complete amplitude saturation term at someMw. We then adopt additional correction terms corresponding to amplification by deep sediments or shallow soft soils, and anomalous seismic intensity distribution in order to improve prediction.

Using the seismic activity model in the National Seismic Hazard Maps for Japan, risk curves were calculated for the exceedance probability in 30 years regarding building damage, i.e., the number of completely destroyed buildings, due to earthquake motion in municipalities throughout all of Japan. In calculation, building data were created using 250 m mesh, and loss functions of wooden and nonwooden buildings were set. Analysis was performed by constructing a methodology considering the spatial correlation of dispersion of earthquake hazards and dispersion based on the planer extension of municipalities. Furthermore, we show the usage of calculated risk curves, for selecting assumed earthquakes and quantitatively estimating aseismic effects of wooden buildings.

In this study, a method for simulating the ground motion of megathrust earthquakes at periods of approximately 2 s and longer was validated by using the characterized source model combined with multi-scale spatial heterogeneity. Source models for the M W 8.3, 2003 Tokachi-oki earthquake were constructed, and ground motion simulations were conducted to test their performance. First, a characterized source model was generated based on a source model obtained from waveform inversion analysis. Then, multi-scale heterogeneity was added to the spatial distribution of several source parameters to yield a heterogeneous source model. An investigation of the Fourier spectra and 5 % damped velocity response spectra of the simulated and observed ground motions demonstrated that adding multi-scale heterogeneity to the spatial distributions of the slip, rupture velocity, and rake angle of the characterized source model is an effective method for constructing a source model that explains the ground motion at periods of 2–20 s. It was also revealed how the complexity of the parameters affects the resulting ground motion. The complexity of the rupture velocity had the largest influence among the three parameters.

We compiled the stress drops on the asperities in inland earthquakes caused by strike-slip faults. Then, we applied the log-normal distribution to the data and obtained the medium of 10.7 MPa and the logarithmic standard deviation of 0.45. Also, we compiled the stress drops on the asperities in inland earthquakes caused by reverse faults and obtained the medium of 17.1 MPa and the logarithmic standard deviation of 0.39.

The 2011 M 9.0 Tohoku-Oki earthquake is the largest earthquake that occurred in and around Japan since the beginning of the recorded history. This megathrust event initiated approximately 100km off-shore Miyagi prefecture, in northeast Japan, and its rupture extended 400-500km along the subducting Pacific plate. This is the first M 9-class earthquake that has been closely recorded by a dense seismograph network. Strong motions of this earthquake are characterized by large seismic intensities and peak ground accelerations (PGA), long durations, and wideness of the area that experienced intense shaking. The ground motions were recorded by 1223 K-NET and KiK-net stations. The PGA exceeded gravity at 20 sites; the largest PGA, of 2933 gals, was observed at the K-NET Tsukidate station (MYG004). The attenuation of the recorded peak values shows a possibility of saturating strong ground motion amplitude with the magnitude. The complex features of the accelerograms and velocity waveforms are discussed in connection with the source processes estimated using long and short period waveform data. Due to the large ground motions and tsunamis associated with this event, more than 16 thousand people were killed and more than 360 thousand houses and buildings were totally or partially destroyed. Although the tsunamis were the primary cause of damage, the strong shaking, liquefaction and landslides also brought serious destruction. However, it was reported that the damage ratios of houses and buildings directly due to shaking were not as high as for the former earthquakes having comparable seismic intensities and PGA. The recorded ground motions at most stations where the seismic intensities and PGA were large had dominant periods shorter than 0.5s and relatively poor power in the 1-2s period range which has strong influence on the damage of few-stories wooden houses. The main reason for the short-period predominance is the amplification due to the low-velocity superficial layer and can be roughly explained by empirical amplification factors for 0.1-0.5s periods. Long-period ground motions were also observed. The velocity response spectra (5% dumping) for periods of 4-20s reached around 100cm/s at many stations, mainly in the Tohoku and Kanto regions. This level may be considered not very large taking into account that the Tohoku-Oki earthquake was an M 9-class event. In the Kanto district, at epicentral distances of 300-400km, liquefaction widely occurred at the artificially reclaimed land in Tokyo and Chiba bay areas and the basin of major rivers, such as the Tone and Ara. The damage (e.g., cutoff of lifelines and differential settlement of house-basements) due to liquefaction was very severe. In this paper we summarize the strong motion characteristics associated with the M 9.0 Tohoku-Oki earthquake and review the latest results from the viewpoint of strong motions.

本論文では、時間軸の起点を1890 年から30 年ごとに変化させた確率論的地震動予測地図を作成し、同じ期間に実際に発生した地震によるハザードマップと対照させることで確率論的地震動予測地図の確からしさの検証を試みた。その結果、全国の地震ハザードの総量として確率論的地震動予測地図はおおむね実績と調和的であると評価された。また、最大影響カテゴリーがIとIIの地域では、事前の超過確率が高い地点ほど震度6 弱以上を経験した割合が多く、確率論手法の有用性を支持する結果を得た。一方、最大影響カテゴリーがIIIの地域はそもそも事前の超過確率が低い地点が多く、震度6 弱以上を受ける具体的な地域を事前の超過確率の高低から予測することは難しいことが明らかとなった。これらより、地域の地震環境に応じてリスクマネジメントの考え方を使い分ける必要性を指摘した。

This report describes a case of fetal mediastinal teratoma complicated by hydrops fetalis managed successfully by aspiration of the tumor cyst fluid. Fetal mediastinal teratomas are rare tumors that cause hydrops fetalis or fetal demise in the prenatal period and respiratory distress in the neonatal period. The patient presented with a large cystic mass in the thoracic cavity complicated by hydrops fetalis. The hydrops resolved after fetal aspiration of the tumor cyst fluid. The infant was born without respiratory distress, and tumor resection was performed at the age of 30 days. The postoperative course was uneventful, and the patient was in good health 6 months postoperatively.

To review the recent Japanese experience with prenatally diagnosed congenital diaphragmatic hernia (CDH) based on a multi-institutional survey. A multicenter, retrospective cohort study was conducted on 117 patients born between 2002 and 2007 with isolated prenatally diagnosed CDH. All patients were managed by maternal transport, planned delivery, immediate resuscitation and gentle ventilation. The primary outcome measurements were the 90-day survival and intact discharge. The examined prenatal factors included gestational age (GA) at diagnosis, lung-to-head ratio (LHR), lung-to-thorax transverse area ratio (L/T) and liver position. Physical growth and motor/speech development were evaluated at 1.5 and 3 years of age. Data were expressed as the median (range). The mean GA at diagnosis was 29 (17–40) weeks. The LHR and L/T were 1.56 (0.37–4.23) and 0.11 (0.04–0.25), respectively. There were 48 patients with liver up. The mean GA at birth was 38 (28–42) weeks. The 90-day survival rate and intact discharge rate were 79 and 63%, respectively. Twelve patients had major morbidity at discharge, and 71% of these patients had physical growth or developmental retardation at 3 years of age. This multicenter study demonstrated that the 90-day survival rate of isolated prenatally diagnosed CDH was 79%, and that subsequent morbidity remained high. A new treatment strategy is needed to reduce the mortality and morbidity of severe CDH.

An accurate prenatal assessment of the patients' severity is essential for the optimal treatment of individuals with congenital diaphragmatic hernia (CDH). The purpose of this study was to clarify the reliability of the lung to thorax transverse area ratio (L/T) as a prenatal predictive parameter.A multicenter retrospective cohort study was conducted on 114 isolated CDH fetuses with a prenatal diagnosis during the period between 2002 and 2007 at five participating centers in Japan. The relationship between the gestational age and the L/T was analyzed. The most powerful measurement point and accurate cutoff value of the L/T was determined by an analysis of a receiver operating characteristic curve, which was verified by comparing the patients' severity.There was a negative correlation between the gestational age and the L/T in the non-survivors, and no correlation in the survivors. There were significant differences in the parameters which represented the patients' severity including the respiratory and circulatory status, the surgical findings, and the final outcomes between the groups divided at 0.080 in the minimum value of the L/T during gestation.The L/T was not strongly influenced by the gestational age, and it was found to be a reliable prenatal predictive parameter in fetuses with isolated CDH.

This study evaluates and compares seismic risks associated with inland crustal earthquakes in Japan on the basis of published data available on the Japan Seismic Hazard Information Station (J-SHIS). First, taking account of prediction uncertainty of the attenuation law of seismic intensity, the evaluation method for population exposure (PEX) to seismic intensity is presented. The method is applied to 333 seismic events potentially caused by main active faults (154 cases) and other active faults (179 cases). The relationship between population exposure and the probability of occurrence of seismic events (“P-PEX relation”) and the resultant seismic risk curves are obtained. Generalized risk index which incorporates the effects of focusing on urgency (probability) or significance (PEX) is defined, producing various risk rankings of active faults.

National seismic hazard maps for Japan with meshes of 1×1 km2 were published by the Earthquake Research Committee of Japan in March 2005. They are updated annually to reflect time passage of event recurrence (NIED 2005). Since the probabilistic seismic hazard maps focus on estimates for 30 and even 50 years, strict validation of the maps requires probabilistic and statistical approaches with future data. Nevertheless, in this study, as the first step in verifying the validity of the maps, we compared the Japan Meteorological Agency (JMA) instrumental intensities from strong-motion records for the 10-year period ending 31 December 2006 with the corresponding values on the probabilistic hazard maps. The JMA instrumental intensity is a cumulative strong motion indicator, which was adjusted to match the scale previously used to measure seismic intensity, which was based on human response and an index of damage. The JMA intensity scale has 10 grades from 0 to 7 (5 and 6 were divided in lower and higher) and is described at http://www.jma.go.jp/jma/kishou/know/shindo/shindokai.html. Explanations of individual intensities can be found at http://www.jma.go.jp/jma/kishou/know/shindo/explane.html. Although corresponding peak ground acceleration could not precisely be adapted to the intensity scale, relative peak ground acceleration is indicated in http://en.wikipedia.org/wiki/Japan\_Meteorological\_Agency\_seismic\_intensity_scale. JMA has promptly reported this intensity since April 1996 (http://www.jma.go.jp/en/quake/). Verification was done using all of K-NET's strong-motion records for the period 1 January 1997 through 31 December 2006. K-NET is an observation network that uniformly covers all of Japan with stations in polygonal configurations that cover areas about 25 kilometers in size. Network operations began in 1997 with 1,000 stations. New observation sites—many of them in the Kanto metropolitan area—have been added since then. The number of observation sites peaked at 1,035, but by the end of 2006 the number had dropped to 1,028 stations, including …

The 2007 Niigata-ken Chuetsu-oki earthquake generated strong ground motions in Kashiwazaki and Kariwa, where the world largest nuclear power plant was in operation. Due to the complexity of the aftershock distribution, activation of the northwest-dipping fault and/or the southeast-dipping fault is proposed. To explore the fault geometry and source process of the earthquake, we performed multi-time window linear waveform inversions for both the fault planes from near-fault strong motion data. A fault plane model of 30 km in length by 24 km in width was set to cover the region of aftershock distribution within 24 h of the mainshock. Both inverted slip models provided moment magnitudes of 6.7 with a small asperity near the rupture starting point, and a large asperity approximately 10 km southwest of the rupture initiation, which is located in the region of relatively sparse aftershock distribution. Both the small and large asperities are located near the intersection between the two conjugate fault plane models, and the asperities of both models have similar radiation patterns. Therefore, the difference of the residuals between the observed and synthetic waveforms for both models was not significant, indicating that it is difficult to conclude which fault is the rupture.

The variation of ground motions at specific stations from events in six narrow areas was inspected by using K-NET and KiK-net records. A source-area factor for individual observation stations was calculated by averaging ratios between observed values for horizontal peak acceleration and velocity, as well as acceleration response spectra for 5% damping, and predicted values using a ground-motion model (usually known as an attenuation relation) by Kanno et al. (Bull Seismol Soc Am, 96:879–897, 2006). Standard deviations between observed and predicted amplitudes after the correction factor are less than 0.2 on the logarithmic scale and decrease down to around 0.15 in the short-period range. Intra-event standard deviation clearly increases with decreasing distance due to differing paths around near source area. Standard deviations may increase with amplitude or decrease with magnitude; however, both amplitude and magnitude of the data are strongly correlated with distance. The standard deviation calculated in this study is obviously much smaller than that of the original ground-motion model, as epistemic uncertainties are minimized by grouping ground motions at specific stations. This result indicates that the accuracy of strong ground motion prediction could be improved if ground-motion models for specified region are determined individually. For this to be possible, it is necessary to have dense strong-motion networks in high-seismicity regions, such as K-NET and KiK-net.

Purpose The purpose of the paper was to study the potential risk and management of adult biliary atresia (BA) patients. Materials and Methods Clinical courses and biochemical data were retrospectively analyzed in 52 BA patients who were operated in our department and are now older than 15 years, with special emphasis on 47 patients who survived beyond the age of 20 years. Results Of these 47 patients, 45 (95.7%) are employed, receiving higher education, and/or married. Thirty-three patients showed favorable liver function at the age of 20 years with their native liver. Thereafter, 6 (18.2%) developed liver dysfunction after working hard or pregnancy. In these 6 patients, cholinesterase levels were significantly lower at the age of 20 years than those in the 27 stable patients (239.5 ± 42.6 vs 285.8 ± 47.5, P = .0216), whereas no significant difference was found in alanine aminotransferase, aspartate aminotransferase, or total protein levels at the age of 20 years or in any biochemical parameters at the age of 15 years. Of the 14 transplanted patients, 5 who underwent transplantation after the age of 20 years had relatively uneventful courses until the age of 20 years; however, their biochemical data already showed significant deterioration at puberty. Conclusion Social activities and pregnancy should be managed individually according to the risk assessment for potential hepatic failure even in stable adult BA patients. A falling cholinesterase level after the age of 20 years may predict the risk for the late hepatic dysfunction.

Following the 1995 Hyogo-ken Nanbu Kobe. Earthquake, the Japanese government, in an effort to prevent future earthquake disasters, installed networks consisting of a large number of strong-motion observation stations. Further, national seismic hazard maps were made available to the public on an Internet website in March 2005 by the Headquarters for Earthquake Research Promotion. However, these maps indicate only the local seismic intensity for Japan, as empirically con- verted from predicted peak velocity in consolidated soils. For various applications, other strong-motion indexes such as the response spectral acceleration are required. In this study, a database of whole Japanese strong ground motion records between 1963 and 2003 is established in order to identify a new standard attenuation relation for Japan, for response acceleration as well as peak value. It is usually very difficult to determine a suitable model form due to the large variability of strong-motion data and correlation among the model variables, because the strong coupling of variables in an attenuation model, and the statistical power of the data is often not large enough to determine the necessity of these parameters. Therefore, in this study, our model has only three variables: earthquake magnitude, shortest distance to the seismic fault plane, and focal depth. To improve predictions given by the model, site correction terms are adopted and additional terms for correcting regional anomalous seismic intensity with respect to the base model are determined. The good fit between the model and observed strong-motion records suggests that the new model is reasonably robust.

This study deals with the advancement process of neuroblastoma through clinical observations and circulating tumor cell exploration. Clinical feature, tumor biology, and circulating tumor cell detected by the previously described polymerase chain reaction (PCR) method were analyzed in 31 patients with advanced neuroblastoma treated in our department since 1991 through 2004. Treatment was completed in 28 patients, of whom 17 are alive without the disease and 11 died. The primary lesion was not confirmed in 2 patients with disseminated metastasis, both of whom showed positive circulating tumor cell. Circulating tumor cell was positive in 6 of 9 examined at their first appearance at the hospital, all had stage 4 disease, and 4 of the 6 (66.7%) died of systemic spread of the disease. N-myc was amplified in 15 patients, of whom only 2 (13.3%) died of systemic metastasis. N-myc amplification did not correlate with positive circulating tumor cell. A certain population of neuroblastoma may provide circulating tumor cells from the early period of the disease to form metastatic lesions independently of the primary lesion, which must be regulated by factors other than N-myc. Circulating tumor cells may suggest higher risk for systemic dissemination and poor prognosis.

Gastric rupture is extremely rare in childhood beyond the neonatal period. We describe a previously healthy 6-year-old girl with a large laceration along the greater curvature on the posterior wall of the stomach. The patient was admitted to a neighboring hospital because of vertigo with 1-day history of intractable vomiting and epigastric pain. Although abdominal distension was noticed during the physical examination, muscular rigidity was not detected on palpation. Laboratory data showed severe hypotonic dehydration and moderate metabolic acidosis with hyperkalemia. She suddenly developed cardiac arrest within an hour after admission. After resuscitation, surgical consultation was obtained. Abdominal X-ray and ultrasound revealed abdominal free air and massive cloudy ascites. At laparotomy, there was a large laceration on the greater curvature of the stomach. Pathology of the gastric wall showed mucosal necrosis while the musculature remained intact consistent with an acute gastric ulcer. Since clinical condition of gastric rupture deteriorates rapidly, early diagnosis and appropriate treatment is essential for good prognosis. One should consider that ulcer formation might cause gastric rupture in childhood.

The 2004 Mid Niigata Prefecture earthquake (37.289°N, 138.870°E, 13.1 km, MJMA 6.8; JMA), also known as the 2004 Niigata Prefecture Chuetsu earthquake, was a thrust type earthquake that occurred on October 23, 2004 at 17:56 (JST). Strong ground motions of PGA 800-1700 cm/s2 and PGV 60-130 cm/s were observed at stations located immediately above the source region. We deduced the rupture process of this earthquake with a multi-time-window linear waveform inversion procedure. We used near-fault strong ground motion data observed at nine K-NET and KiK-net stations within 50 km from the epicenter. In order to obtain appropriate Green’s functions for the waveform inversion, we constructed two velocity structure models for stations on the hanging wall and one structure model for stations on the footwall. The estimated total slip distribution contains three asperities: (a) around the hypocenter, (b) in the upper-middle section of the fault plane, and (c) southwest of the hypocenter. The maximum slip is 3.8 m at the hypocenter and the total seismic moment is 1.2 × 1019 Nm, which corresponds to Mw=6.7. The moment rate functions in asperities (a) and (c) have a short rise time, while those in asperity (b) have a longer rise time.

A great earthquake, named the 2003 Tokachi-oki earthquake, occurred in the southern Kuril subduction zone on 26th September 2003,4:50 JST (41.7797°N, 144.0795°E, 42 km depth; Japan Meteorological Agency). Its ground motion was recoreded at 655 stations of the nationwide strong motion networks, K-NET and KiK-net. A maximum peak ground acceleration of 988 cm/s2 (gal) was observed at station HKD100 and amplitudes greater than 200 cm/s2 were observed over a wide area of eastern Hokkaido. We used a multi-line linear waveform inversion method to estimate the rupture process from the strong motion data of supplied by 15 stations. We assumed a fault plane model of 140 km × 160 km with strike and dip angles of our fault model are N246°E and 18°, respectively, placed on the estimated upper boundary of the subducting Pacific Plate. The estimated total slip distribution consisted of three major slip areas; (a) around the hypocenter, (b) the northwest part of the fault with the maximum slip of 5.9 m, and (c) the northeast edge of the fault plane. The major asperity (b) was composed of two large slip areas with different slip rate functions: the duration of moment release in the sourtheast part is longer than 15 sec, but in contrast most of the seismic moment of the northwest part was released in a short period of less than 10 sec. Our estimation of the total seismic moment was 2.9 × 1021 N·m which corresponded to Mw = 8.2.