Atellite Ba Ed T Unami And Earthquake Early Warningy Tem PdfBy Zara W. In and pdf 19.05.2021 at 06:04 9 min read
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Metrics details. Most of the AIS data showed notable deviation of the ship heading from the course over ground during the tsunami passage. An equation of motion due to wave drag and inertia forces was examined for an offshore movable floating body.
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- Deep-ocean Assessment and Reporting of Tsunamis
- Earthquake Monitoring and Early Warning Systems
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Metrics details. Most of the AIS data showed notable deviation of the ship heading from the course over ground during the tsunami passage. An equation of motion due to wave drag and inertia forces was examined for an offshore movable floating body. We explain that the ship movement in the direction normal to the heading immediately responds to the tsunami current, and relative velocity between the ship and the tsunami current asymptotically become zero.
This indicates the movement velocity of navigating ships in the direction normal to the heading derived from AIS data will work as an offshore tsunami current meter.
We examined the AIS data during the Tohoku tsunami and showed these data could be useful for tsunami source estimation and forecast. The AIS data in the current framework will possibly be a crowd-sourced tool for monitoring offshore tsunami current and tsunami forecast. Great earthquakes and tsunamis have caused significant loss of life and property in coastal communities ITIC In the Sumatra-Andaman, Indonesia, earthquake and the Tohoku, Japan, earthquake, most casualties , for the disaster and 20, for the disaster were caused by the flooding due to the tsunamis Satake Coastal mega cities have to prepare to reduce these losses especially from the tsunamis.
In addition to constructing proper embankments in advance of earthquake and tsunami occurrences Tomita et al. Real-time forecasting of great earthquakes and tsunamis can be utilized for suitable decision-making for disaster mitigation. Real-time forecast systems should be robust and reliable. Current systems are based on real-time Earth monitoring that uses onshore and offshore observations. These observations include seismic waves Allen et al.
Rapid earthquake-source estimation systems using seismic-wave observations are popular. However, these methods estimate a point source that may be indirectly related to tsunamis, and are somehow difficult to accurately constrain the tsunami source dimension particularly for great earthquakes Katsumata et al. It is better to use direct observations of offshore sea level to estimate the resultant tsunami size. Real-time forecasting of great tsunamis based on offshore tsunami observations has been popular.
These forecast systems will be enhanced using real-time geodetic monitoring as well Tsushima et al. Forecast methods using very dense seafloor observation networks have been also proposed independently Maeda et al. These forecast systems using offshore tsunami observations will be robust and reliable. The observatories have to be maintained and sustained at least until the next devastating tsunami. Such an event may occur once typically during tens to hundreds of years at a certain place McCaffrey ; Rong et al.
In general, offshore observatories require higher maintenance costs than onshore observatories, and replacements will be necessary after endurance periods, typically several decades after installation Hirata et al. Tsunami forecast methods especially measurement systems need sustainability as well as reliability NRC ; Bernard and Titov It is desirable to propose and develop other sustainable methods of monitoring and forecasting of great tsunamis. Tsunami as sea-level change could be detected by shipborne GPS.
This indicates that navigating ship networks will serve as offshore tsunami observation networks Inazu et al. However, this requires high-precision GPS facilities on most of the vessels to precisely measure their positions as well as GPS buoys Terada et al. The ship positions in the AIS data do not include vertical position, and they are mostly measured by ordinary GPS with meter-order precision which is employed in ordinary car navigation.
During the Tohoku tsunami, a number of vessels in ports drifted significantly and collisions occurred due to strong tsunami currents Suga et al. The behaviors of the ship horizontal drifts with collision in a port were examined using AIS data with tsunami simulation Matsuda et al.
The ship drifts should be affected by tsunami currents; however, the relationship between them still seems unclear due to a complicated situation in the port. On the other hand, AIS data were also available in offshore regions during the tsunami. It was reported that movement directions of several offshore ships deviated during the tsunami Makino ; Liu et al. However, these reports merely showed the facts and hardly described any quantitative relationship between the deviations and the tsunami.
There is still much room to be clarified regarding the expected relationship between ship drifts and tsunamis. In the present study, we examine the AIS records of multiple ships navigating near the source region of the Tohoku tsunami. The relationship is investigated quantitatively between the ship horizontal movement or drift and the tsunami current.
We describe the usefulness of the AIS data to measure offshore tsunami currents and to be applied to tsunami forecast. The AIS data include dynamic and static information. The number of ships recognized with AIS data is increasing year by year with increasing seaborne trade and number of satellites Tournadre ; Willick Our tsunami simulation also shows such tsunami heights and currents Fig. Due to such strong tsunami currents, as mentioned above, a number of vessels in the ports drifted significantly, resulting in collisions and severe damages to buildings and structures there.
Just after the earthquake occurrence, although most of the AIS data offshore of Miyagi were lost because coastal stations failed to receive the AIS data probably due to near-source strong ground motion, some data were obtained until the tsunami devastated the coast Fig.
The tsunami simulation is based on non-linear long-wave equations Saito et al. Ship distributions derived from AIS data during the Tohoku tsunami. These ships were typical commercial ships such as cargo ships and tankers. COG is the direction of true ship movement. We show examples of time evolution of AIS records of navigating ships Fig.
Just after the earthquake, the captain may have reduced the ship velocity from 6. We investigate the relationship between the deviation and the tsunami current.
Ship propulsion during ordinary offshore navigation is imposed mostly in the HDG direction. Here, ship velocity and tsunami current are examined in the direction normal to the HDG Fig. The tsunami current component in the HDG-normal direction is calculated at respective ships by using a tsunami simulation Saito et al.
We confirm notably good agreement between the ship velocity and the tsunami current in the HDG-normal direction for almost all the ships navigating offshore Fig. Thus, these AIS data are a clear proxy for tsunami currents with the equivalent amplitude in the HDG-normal direction. Observed ship velocity green and simulated tsunami current red components in the HDG-normal direction. The ship velocity component is calculated from Eq.
We evaluate the relationship between the ship velocity and the tsunami current Fig. The floating body is the navigating vessel. Since ship propulsion is likely imposed in the HDG direction in ordinary offshore navigation with autopilot, the equation of motion is applied in the HDG-normal direction in which only the external force works:.
The ship velocity of Eq. The equation is often rewritten as Reddy and Swamidas :. Formulations similar to Eq. Here, we obtain:. We suppose a motionless ship is forced by transient tsunami current v c in the HDG-normal direction, and consider the response of the ship velocity v to the tsunami current. Time evolution of a the solution of Eq. Tsunamis involve long waves with longer periods than ordinary wind waves. It is reasonable that ships quickly respond to the drag force due to great tsunamis with such amplitudes and time scales Heo et al.
This interpretation is very useful since Eq. In such severe cases, the response will be more immediate and the approximation is more robust. If B is larger, the response time will be longer.
Thus, most AIS data in the current framework are already suitable as tsunami current meters, especially for great tsunamis.
Once the tsunami velocity can be measured by the ship velocity component in the direction normal to the ship heading, it is worth carrying out inversion for real-time tsunami forecast to estimate source and tsunami height. Fuji et al. They employed the tsunami current instead of tsunami height for the inversion for the tsunami source. In the present study, we employ tsunami currents derived from the observational ship drifting Fig. Referring to our previous study Inazu et al.
The result can show mostly similar features in terms of both the source and the maximum tsunami height at the coast, compared to those from the validated source Fig. This indicates that ship velocity components in the HDG-normal direction of multiple ships derived from AIS records will be possibly useful for tsunami source estimation and forecast in addition to conventional tsunami height observations at fixed stations.
In b , dots are allocated unit sources. Red and gray curves in c are derived from the estimated source and from Fig. The AIS records of offshore navigating vessels were examined during the Tohoku tsunami.
Using an equation of motion of an offshore movable floating body, we obtained an analytical solution and understood that the ships immediately respond to the great tsunami current with the equivalent velocity amplitude in the HDG-normal direction. This study indicates AIS data in the current framework can be used as a tsunami current meter in one direction for each vessel. We also showed that the observed tsunami velocity derived from the AIS data of multiple vessels during the Tohoku tsunami could be useful for tsunami source estimation and forecast.
The current AIS data are already provided via almost real-time successive transmission. We hope to exploit this large amount of data and expect the use of AIS data will become a new method for measuring and forecasting great tsunamis.
Similar concepts of diverting information from crowd-sourced agents to Earth monitoring recently have been also applied to grasp earthquakes Kong et al. Suitable methods for forecast will need to be developed. Such methods will be adopted also for assimilating wave height fields derived from satellite altimetry Hamlington et al. As long as based on Eq. Further discussion will be necessary for automatically obtaining high-quality AIS data in real-time operation. Although Japan already has dense offshore observatories for real-time tsunami monitoring and forecasting Kawai et al.
The density of vessels increases in coastal mega cities with highly economic activities. Tsunami disaster mitigation is especially important for such coastal mega cities due to their large populations. Maritime activities will continue as long as populations remain large.
Deep-ocean Assessment and Reporting of Tsunamis
Crowdsourced earthquake early warning. PubMed Central. Minson, Sarah E. Earthquake early warning EEW can reduce harm to people and infrastructure from earthquakes and tsunamis, but it has not been implemented in most high earthquake -risk regions because of prohibitive cost. Common consumer devices such as smartphones contain low-cost versions of the sensors used in EEW. Although less accurate than scientific-grade instruments, these sensors are globally ubiquitous. Through controlled tests of consumer devices, simulation of an M w moment magnitude 7 earthquake on California's Hayward fault, and real data from the M w 9 Tohoku-oki earthquake , we demonstrate that EEW could be achieved via crowdsourcing.
Being situated on the major subduction zones in conjunction with a considerable number of submarine active faults and coastal volcanoes, Japan has a long history of catastrophic tsunami events. Consequently, enormous efforts in disaster mitigation, particularly in relation with tsunami hazards, have been made across the country. It is of our interest to review the developments of tsunami observing systems in Japan, which may lead to a global implication beyond national boundaries. In this paper, we first discuss, in general, the evolution of past to present tsunami observing systems available around the territory of Japan. More specifically, we identify the existing offshore observational networks that are mainly consisted of cabled ocean bottom pressure gages and global navigation satellite system buoys, and briefly analyze their performance and viability in the long-term future. In that context, we also appraise the potential of emerging technologies in the offshore tsunami detection leveraging unconventional platforms such as commercial ships and airplanes, which have recently been introduced by several studies in Japan.
Radiation early warning system. This unit was developed to measure all relevant parameters necessary to detect and track radioactive contamination at an early stage. The station consists of the following components: Radiation measuring channel for ambient gamma dose rate. Meteorological measurement channels for air temperature and humidity, wind direction and wind speed, and precipitation. Data processing and storage unit. The system is capable of unattended operation and data acquisition even under adverse environmental conditions. Connection to a central processing platform may be achieved via leased line, dial up over public switched telephone network PSTN , or radio-frequency transmission.
Earthquake Monitoring and Early Warning Systems
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SUMMARY The chapter presents planners with 1 a description of the most hazardous geologic phenomena-earthquakes, volcanoes, and tsunamis-and their effects; 2 a discussion of how to use existing information to assess the hazards associated with these phenomena and incorporate mitigation measures early In an Integrated development study; 3 sources of geologic data and maps; and 4 information with which to make key decisions early in the planning process.
The M7. Most of the other epicenters visible on the map are aftershocks. Explore This Park. Article Monitoring Seismic Activity.
Офицер кивнул, достал из пачки Дукадо сигарету, посмотрел на плакат с надписью No fumar - Не курить - и все же закурил. - Наверное, я должен был обратить на это внимание, но тот тип показался мне настоящим психом.