Far-field crustal movements before and after the 2011 Ms9.0 Japan earthquake from GPS observations

The paper gives an analysis of the displacement time series before and after the March 11,2011 Ms9.0 east Japan earthquake and co-seismic displacements observed at continuous GPS stations in and around China. The results showed a broad-scaled related elastic-rebound process and some premonitory horizontal crustal movements to this earthquake over this vast area.

Anomalous variations in ionospheric TEC prior to the 2011 Japan Ms9.0 earthquake

The ionospheric total-electron-content （IGS） network and the VTEC data from the GPS （TEC） data provided by the International GNSS Service reference stations of Crustal Movement Observational Network of China（CMONC） were processed and statistically analyzed to search for earthquake-related TEC anomalies prior to the 2011 magnitude 9.0 earthquake in Japan. Preliminary results showed that anomalous variations oc- curred 6 - 11 days and 0 - 4 days prior to the earthquake. After considering solar activity, geomagnetic condi- tions, and proximity in space and time to the earthquake, we tentatively concluded that the anomalous increase on March 5 may be related to the earthquake.

Co-seismic displacements of 2011 Japan Mw9.0 earthquake recorded by far-field GPS stations

Co-seismic displacements of the 2011 Mw9.0 Japan earthquake recorded by GPS stations in China and surrounding areas showed a movement toward the epicenter. The horizontal displacements were up to 1 - 3 cm in northeastern China, 3 -8 mm in the North China, and 2 cm in the Korean peninsula. The vertical movements in China were small uplifts.

Numerical simulation of co-seismic deformation of 2011 Japan Mw9.0 earthquake

Co-seismic displacements associated with the Mw9.0 earthquake on March 11, 2011 in Japan are numerically simulated on the basis of a finite-fault dislocation model with PSGRN/PSCMP software. Compared with the inland GPS observation, 90% of the computed eastward, northward and vertical displacements have residuals less than 0.10 m, suggesting that the simulated results can be, to certain extent, used to demon- strate the co-seismic deformation in the near field. In this model, the maximum eastward displacement increa- ses from 6 m along the coast to 30 m near the epicenter, where the maximum southward displacement is 13 m. The three-dimensional display shows that the vertical displacement reaches a maximum uplift of 14.3 m, which is comparable to the tsunami height in the near-trench region. The maximum subsidence is 5.3 m.

Spatio-temporal characteristics of aftershocks and seismogenic structure of the 2011 Mw9.0 Tohoku earthquake,Japan

The Tohoku megathrust earthquake, which occurred on March 11, 2011 and had an epicenter that was 70 km east of Tohoku, Japan, resulted in an estimated ten′s of billions of dollars in damage and a death toll of more than 15 thousand lives, yet few studies have documented key spatio-temporal seismogenic characteristics. Specifically, the temporal decay of aftershock activity, the number of strong aftershocks (with magnitudes greater than or equal to 7.0), the magnitude of the greatest aftershock, and area of possible aftershocks. Forecasted results from this study are based on Gutenberg-Richter’s relation, Bath’s law, Omori’s law, and Well’s relation of rupture scale utilizing the magnitude and statistical parameters of earthquakes in USA and China (Landers, Northridge, Hector Mine, San Simeon and Wenchuan earthquakes). The number of strong aftershocks, the parameters of Gutenberg-Richter’s relation, and the modified form of Omori’s law are confirmed based on the aftershock sequence data from the Mw9.0 Tohoku earthquake. Moreover, for a large earthquake, the seismogenic structure could be a fault, a fault system, or an intersection of several faults. The seismogenic structure of the earthquake suggests that the event occurred on a thrust fault near the Japan trench within the overriding plate that subsequently triggered three or more active faults producing large aftershocks.

Co-seismic deformation of 2011 Mw9.0 Japan earthquake observed by InSAR technique

Co-seismic line-of-sight displacements of the 2011 Mw9.0 Japan earthquake derived from InSAR data of Envisat ASAR, ALOS PALSAR and TerraSAR-X show a maximum value of about - 245cm to -221cm near the epicenter. This result is in good agreement with the result of GPS measurement. The ob- served displacement pattern suggests an earthquake-rupture zone over 500km long, with a ground-motion pat- tern in the vicinity of the northern segment more complex than that of the southern segment, possibly due to immediate aftershocks that occurred between satellite passes.

Strain Energy Release from the 2011 9.0 Mw Tōhoku Earthquake, Japan

The purpose of this paper is to compare the strain energy released due to elastic rebound of the crust from the tragic 2011 9.0 MwTōhoku earthquake in Japan with the observed radiated seismic energy. The strain energy was calculated by analyzing coseismic displacements of 1024 GPS stations of the Japanese GEONET network. The value of energy released from the analysis is 1.75 × 1017J, which is of the same order of magnitude as the USGS-observed radiated seismic energy of 1.9 × 1017Nm (J). The strain energy method is independent of seismic methods for determining the energy released during a large earthquake. The analysis shows that although the energy release is concentrated in the epicentral region, about 12% of the total energy was released throughout the Japanese islands at distances greater than 500 km west of the epicenter. Our results also show that outside the epicentral region, the strainenergy was concentrated along known tectonic zones throughout Japan.

Coseismic gravity and displacement changes of Japan Tohoku earthquake(Mw 9.0)

The greatest earthquake in the modern history of Japan and probably the fourth greatest in the last 100 years in the world occurred on March 11, 2011 off the Pacific coast of Tohoku.Large tsunami and ground motions caused severe damage in wide areas, particularly many towns along the Pacific coast. So far, gravity change caused by such a great earthquake has been reported for the 1964 Alaska and the 2010 Maule events. However, the spatial-temporal resolution of the gravity data for these cases is insufficient to depict a co-seismic gravity field variation in a spatial scale of a plate subduction zone. Here, we report an unequivocal co-seismic gravity change over the Japanese Island, obtained from a hybrid gravity observation（combined absolute and relative gravity measurements）. The time interval of the observation before and after the earthquake is within 1 year at almost all the observed sites, including 13 absolute and 16 relative measurement sites, which deduced tectonic and environmental contributions to the gravity change. The observed gravity agrees well with the result calculated by a dislocation theory based on a self-gravitating and layered spherical earth model. In this computation, a co-seismic slip distribution is determined by an inversion of Global Positioning System（GPS） data. Of particular interest is that the observed gravity change in some area is negative where a remarkable subsidence is observed by GPS, which can not be explained by simple vertical movement of the crust. This indicated that the mass redistribution in the underground affects the gravity change. This result supports the result that Gravity Recovery and Climate Experiment（GRACE） satellites detected a crustal dilatation due to the 2004 Sumatra earthquake by the terrestrial observation with a higher spatial and temporal resolution.

Digitization characteristics of geothermal information and structural analysis of 2011 off the Pacific coast of Tohoku Ms9.0 earthquake

Earthquake is one of the difficult problems that can not be solved as of this writing since the time when mod- em science was initiated over 300 years ago, and irregular events cannot be dealt with by using quantities examples before and followed by a view of the number of analysis systems in modem science ; meanwhile, it covers the problem that how to use changeable information. Structural analysis method is developed particularly for the study of evolutionary transitional processes of the changing events by employing irregular information, and emphasizes the primitiveness of changes in events. Based on the data of sounding observation every 08 o＇ clock and 20 o＇ clock per day from China Meteorological Administration, in this paper, we employ the digital structural analysis method to analyze the process of the special, structural characteristics of 2011 off the Pacific coast of Tohoku Ms9.0 earthquake. The result shows that the method can reflect the process of geothermal structures before and after earthquake; it can reflect the congruity between geothermal ＂heat level＂ and the level of earthquake energy. When the structure before the earthquake is ＂the counter clockwise rolling current and the unstable structures＂ with ＂dry in lower levels and wet in upper levels＂, we should be worry about the problem of earthquake. In a word, geothermal information could reveal that earthquakes really would be ＂heralded＂.

Seismic Hazard Assessment for Japan after the 2011 Tohoku-Oki Mega-Thrust Earthquake （Mw9.0）

The Tohoku-Oki earthquake （Mw 9.0） of March 11,2011, was the largest event in the history of Japan. This magnitude 9.0 mega-thrust earthquake initiated approximately 100 km off-shore of Miyagi prefecture and the rupture extended 400-500 km along the Pacific plate. Due to the strong ground motions and tsunami associated by this event, approximately twenty thousand people were killed or missing and more than 220 thousands houses and buildings were totally or partially destroyed. This mega-thrust earthquake was not considered in the national seismic hazard maps for Japan that was published by the HERP （headquarters for earthquake research promotion） of Japan. By comparing the results of the seismic hazard assessment and observed strong ground motions, we understand that the results of assessment were underestimated in Fukushima prefecture and northern part of Ibaraki prefecture. Its cause primarily lies in that it failed to evaluate the Mw 9.0 mega-thrust earthquake in the long-term evaluation for seismic activities. On the other hand, another cause is that we could not make the functional framework which is prepared for treatment of uncertainty for probabilistic seismic hazard assessment work fully. Based on the lessons learned from this earthquake disaster and the experience that we have engaged in the seismic hazard mapping project of Japan, we consider problems and issues to be resolved for probabilistic seismic hazard assessment and make new proposals to improve probabilistic seismic hazard assessment for Japan.

Responses of the East Component of Beijing GNSS Continuous Observation Stations to the 2011 Japan M_W 9.0 Earthquake

Several new demands have been put forward for the application of the Beijing continuous GNSS observations due to some particular reasons, such as the limited coverage of the observation network, the different construction and management criterion executed by different units and the intense interference resulting from human activity. In this paper, necessary processing of data is carried out, including more accurate calculation, corrections to the replacement, outliers and relocation of equipment, and elimination of linear trends in the E-component for every station. The E-components of the 16 available stations showed a lower sawtooth wave anomaly （slowly westward propagating） before the 2011 Tohoku Mw9. 0 earthquake, a coseismic step rebound （rapid eastward propagating） and a post-seismic D-shaped recovery. These steps constituted a complete earthquake process which was rarely seen before in the GNSS observations and provides a good example for further study. Moreover, the rapid eastward propagating during the earthquake is not influenced by the size of the given normal values, which may play a significant role in earthquake forecasting and early warning.

Deformation caused by the 2011 eastern Japan great earthquake monitored using the GPS single-epoch precise point positioning technique

Crustal deformation can provide constraints for studying earthquake rupture and shock wave transmission for the Mw9.0 eastern Japan great earthquake. Using the single- epoch precise point positioning （PPP） method and the appropriate positioning flow, we process GPS data from six IGS （International GNSS Service） sites （e.g., MIZU, TSK2, USUD, MTKA, AIRA and KSMV） located in Japan and obtain the positioning results with centimeter scale precision. The displacement time series of the six sites are analyzed using the least squares spectral analysis method to estimate deformations caused by the Mw9.0 mainshock and the Mw7.9 aftershock, and the cumulative displacements after 1 day. Mainshock displacements at station MIZU, the nearest site to the mainshock in the North （N）, East （E）, and Up （U） directions, are -1.202 m, 2.180 m and -0.104 m, respectively, and the cumulative deformations after 1 day are -1.117 m, 2.071 m and -0.072 m, respectively. The displacements at station KSMV, the nearest site to the Mw7.9 aftershock in the N, E and U directions, are -0.032 m, 0.742 m and -0.345 m, respectively. The other sites obviously experienced eastern movements and subsidence. The deformation vectors indicate that the horizontal displacements caused by the earthquake point to the epicenter and rupture. Elastic bounds evidently took place at all sites. The results indicate that the crustal movements and earthquake were part of a megathrust caused by the Pacific Plate sinking under the North American Plate to the northeast of Japan island arc.

日本Ms9.0地震前的重力高频扰动

选取中国重力台网14台gPhone弹簧重力仪组成2个观测剖面,对日本本州东海岸附近海域Ms9.0特大地震前(3月1日至10日)的观测数据进行了分析。结果表明:沿海各台站统一出现了喇叭口状的"重力异常扰动"现象,且扰动异常随震中距的增加呈衰减趋势。

日本Ms9.0地震前的连续重力观测异常

日本Ms9.0地震后,检测了17台(套)gPhone重力仪和成都GS15连续重力观测仪震前3天的观测数据。发现:乌什、郑州台的gPhone重力仪和成都台的GS15重力仪分钟采样在震前3天出现了不明原因的高频异常现象。初步分析表明,成都、乌什在3月9日的日本Ms7.3地震前的16小时产生了纺锤状的隆起现象;郑州台在日本Ms7.3和Ms9.0地震震前出现了明显的柱状异常现象。其异常虽然可以排除热带气旋、人为干扰等因素的影响,但与日本地震的关系以及震前更长时间尺度的异常还有待进一步分析。

Where is English Majors' Future?-A Revelation from Japan Earthquake Dialogue and Michael Dell's Success Story

With an English program Dialogue about Japan earthquake, it is found that English major's future is pale and gloomy. It's just like Michael Dell's success story, when people found direct marketing is a better way, they would try to get dealers out of the way. English majors are facing the embarrass like dealers.

Pre-seismic and Co-seismic Crustal Movements of the M 7.3 Kyushu Earthquake on April 16,2016 in Japan

The time series of coordinates of a large number of GPS stations in the world,processed by Prof. Geoffrey Blewitt with GIPSY software are available at http://geodesy. unr. edu.Based on the time series of coordinates in the global reference frame of IGS08 at more than250 stations of continuous GPS observations,downloaded from the website,the co-seismic displacements of the M7. 3 Kyushu earthquake on April 16,2016 in Japan and the preseismic strain accumulations and displacements in the regional reference frame were obtained. The station of continuous GPS observation at BJFS near Beijing has been quite stable in displacement in the eastern part of China for more than 17 years since the beginning of its operation,and this station is used as the core station in the regional reference frame for the pre-seismic displacement of the Kyushu earthquake of M7. 3. The main feature of the pre-seismic displacements of the Kyushu earthquake is characterized by locking in the crust at and near the epicenter. The anomalous pre-seismic strain accumulation developed in an area of anomalous accumulation of the shear strain component of γ1 on the northeast side of the epicenter,with increasing size of the area and increasing magnitude in γ1. The largest area covered by the anomalous γ1 is about 2000 km2. The change in the E component at BJFS since November 26,2015 was caused by the replacement of the receiver and the antenna at the station. In order to study the shortterm change in displacements at stations at and near the epicenter,the time series at 3 stations with continuous GPS observations,2 at SUWN and DAEJ in south Korea and 1 at BJSH near Beijing were analyzed. The analysis shows that the displacements at the 3 stations have been quite stable in the same manner in east Asia. Thus,BJSH is used as the core station in the regional reference frame of displacement and the displacement time series show that there were no significant short term anomalies before the earthquake.

Temporal variation of gravity-field in North China before and after the 2011 Japan Mw9. 0 earthquake

By using absolute and relative-gravity data recorded by the gravity network in North China, we obtained some large-scale and high-spatial-resolution images of gravity variation in this area for the first time. By analyzing these images, we found that the gravity in Liaodong peninsula area showed an obvious increase of 80 × 10^-8ms^-2 during about one- and-half year before the 2011 Japan Mwg. 0 earthquake, and a rapid decrease after the earthquake. This gravity variation is similar to that observed previously for the 1976 Tangshan 1147.8 earthquake.

Hemorrhagic gastric and duodenal ulcers after the Great East Japan Earthquake Disaster

AIM:To elucidate the characteristics of hemorrhagic gastric/duodenal ulcers in a post-earthquake period within one medical district.METHODS:Hemorrhagic gastric/duodenal ulcers in the Iwate Prefectural Kamaishi Hospital during the 6-mo period after the Great East Japan Earthquake Disaster were reviewed retrospectively.The subjects were 27patients who visited our hospital with a chief complaint of hematemesis or hemorrhagic stool and were diagnosed as having hemorrhagic gastric/duodenal ulcers by upper gastrointestinal endoscopy during a 6-mo period starting on March 11,2011.This period was divided into two phases:the acute stress phase,comprising the first month after the earthquake disaster,and the chronic stress phase,from the second through the sixth month.The following items were analyzed according to these phases:age,sex,sites and number of ulcers,peptic ulcer history,status of Helicobacter pylori(H.pylori)infection,intake of non-steroidal anti-inflammatory drugs,and degree of impact of the earthquake disaster.RESULTS:In the acute stress phase from 10 d to 1mo after the disaster,the number of patients increased rapidly,with a nearly equal male-to-female ratio,and the rate of multiple ulcers was significantly higher than in the previous year(88.9%vs 25%,P<0.005).In the chronic stress phase starting 1 mo after the earthquake disaster,the number of patients decreased to a level similar to that of the previous year.There were more male patients during this period,and many patients tended to have a solitary ulcer.All patients with duodenal ulcers found in the acute stress phase were negative for serum H.pylori antibodies,and this was significantly different from the previous year’s positive rate of 75%(P<0.05).CONCLUSION:Severe stress caused by an earthquake disaster may have affected the characteristics of hemorrhagic gastric/duodenal ulcers.

Influence of the 2011 Mw9. 0 Japan earthquake on groundwater levels in Chinese mainland

This paper gives a description of the co-seismic and post-seismic groundwater level changes induced in Chinese mainland by the 2011 Mw9.0 Japan earthquake, and the corresponding stress changes calculated on the assumption of linear elasticity. The result shows that the main types of changes were oscillations and step increases. The North-South Seismic Belt and the Shanxi Seismic Belt were the main areas affected by the earthquake.

Response of tilt and strain meters in Hubei province to the 2011 Mw9. 0 Japan earthquake

Tih and strain meters of the deformation-observation network in Hubei Province all responded to the Mw9.0 Japan earthquake on March 11,2011. By analyzing the co-seismic responses,we found that firstly there was essentially a linear correlation between response time and epicentral distance. Secondly, there was some correlation between maximum response amplitude and earthquake magnitude as well as between the duration and earthquake magnitude. Thirdly, the response amplitudes and decay rates were different for different types of instruments. Due to less data-sampling frequency, the deformation instruments, could not display the first motion of P and S waves, but responded mainly to far-field surface waves. Before the earthquake, the NS earthtide component recorded by the cave stainmeter at Yichang was distorted for nearly eight hours. While digital deformation observation did not show complete information about the earthquake source, it still reflected some key features of seismic-wave propagation.