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Communications Network

Summary of  Communications Network

The tsunami detection communication network we propose to use for the
countries of Micronesia and Peru is based on  the network used by Pacific
Marine Expermemental Laboratory (PMEL).  PMEL uses DART II buoy sensors to
determine if a tsunami is approaching, these buoys are placed in ocean depths
of about 4,000 feet.  On standard mode, every 6 hours, the buoy sensors report
average water height fluctuations for sampling intervals of 15 seconds to the
warning center; the measurement  sensitivity of the sensor is less than 1 millimeter in 6000 meters.
Tidal reports  have a sampling interval of 15 minutes. Tsunamis that are generated by earthquakes,
cause the  Tsunami Detection Algorithm to turn the DART II system on to event mode. Once the DART II is
turned to the this mode, the system immediately attempts to send the 15 second
report to the tsunami warning center. The maximum delay time for this message is 3
minutes.  The current communication network will have the buoy communicating to
the warning center within 3 minutes. [Real-Time Deep-Ocean Tsunami Measuring,
Monitoring, and Reporting System: The NOAA DART II Description and Disclosure
Christian Meinig, Scott E. Stalin, Alex I. Nakamura NOAA, Pacific Marine
Environmental Laboratory (PMEL) Hugh B. Milburn].

Current Communication Network

                                                                            Picture credit: Christian Meinig, Scott E. Stalin, Alex I. Nakamura (PMEL)

                            Current Communication Network in More Detail      

    The current buoy communication network used by PMEL is outlined in the above diagram.  On standard mode, the surface buoy reports data of the water height  fluctuations every 6 hours to the Iridium Satllite Network.¹³  The data it reports includes the average water column height in millimeters corresponding to 15 minute intervals, battery voltages, status indicator, and time stamp.¹³   "Earthquake waves travel significicantly faster than tsunami waves, and frequently trip the tsunameter into 'Event Mode' before the tsunami arrives. The vertical shifting of the seafloor from the earthquake acts to lift or compress the water column above, showing an increase in pressure as the seafloor  rises, or decrease in pressure as the seafloor falls." On event mode, a tsunami or earthquake is detected because a "detection threshold" in the "Tsunami Detection Algorithm" was exceeded.  At this moment, waveform data is reported instantly with less than a three-minute delay. ¹³   The first message it sends in Event Mode is known as message #0. This message contains the message ID, average water column height that caused the Event mode with three height deviations, the exact time that it was detected, and other data that ensures the validity of this data.  Also, when  the system has reached event mode, the warning center can communicate to the buoy and get more detailed data.  After it has transmitted the initial data, data is continouisly reported every hour unitl the "Tsunami Detection Algorithm" is in a "non-triggered"  status. ¹³

Table 1: DART II performance characteristics

Characteristic Specification
Reliability and data return ratio: Greater than 80%
Maximum deployment depth: 6000 meters
Minimum deployment duration: Greater than 1 year
Operating Conditions Beaufort 9 (survive Beaufort 11)
Maintenance interval, buoy Greater than 2 years
Maintenance interval, tsunameter Greater than 4 years
Sampling interval, internal record: 15 seconds
Sampling interval, event reports: 15 and 60 seconds
Sampling interval, tidal reports: 15 minutes
Measurement sensitivity: Less than 1 millimeter in 6000 meters; 2 x 10-7
Tsunami data report trigger Automatically by tsunami detection algorithm
On-demand, by warning center request
Reporting delay: Less than 3 minutes
Maximum status report interval: Less than 6 hour
Table 1 credit; Christian Meinig, Scott E.Stalin, Alex I. Nakamura, Hugh B Milburn (PMEL)

Communication  to Tsunami Warning Centers

An international Tsunami Warning Center exists in Hawaii. Our plan is to send the warning and data from the buoys through satellite communication to the international tsunami headquarters, which will in turn send a warning to all other tsunami detection headquarters.  We also  plan on having the buoys directly send data through radio communication to regional headquarters in both Peru and Micronesia.

Peru already has a tsunami detection headquarters in place. That headquarter is run by Peru's  navy.  We propose to send the buoys data to this regional tsunami warning center under the condition that if a tsunami is detected the warning will be communicated directly to the people and media without political or further government interference. The sensors communicate the detection of a tsunami within 3 minutes. It would defeat the sensor's efficiency if the warning is delayed by any interference or consultation with government or other authority. Scientists, not government, will determine if a tsunami will hit their country and in what time and with what  strength it will hit. The scientists working at headquarters will issue the warning that will go out to the people through the country's tsunami warning system.

         Unlike Peru, Micronesia does not yet have a headquarters in place. Although at this moment we have not  determined where the regional headquarters for Micronesia will be located, it will likely be located on Micronesia's higher elevations.  The regional communication system for Micronesia will work very similar to that of Peru. We have yet to determine if the headquarters will  also be run by the Navy of Micronesia, or by some international tsunami warning group. Other than these concerns, Micronesia's regional headquarters will have the same structure of communication as that of Peru. Both will recieve data directly from their regional buoys to their headquarters via radio communication, as well as warning from the International headquarters in Hawaiii.

    We propose this communication structure because it is nearly fail-safe. Let's look at two cases. In the case that regional headquaters has a problem, international headquarters, which recieves warnings from all the buoys in the world, will then alert the regional headquarters. In the case that international headquarters has a problem, regional headquarters will still recieve data from their regional buoys and thus can issue a warning.

     Picture Credit: Nasly Jimenez (MIT '09)

         In summary, we propose that Peru and Micronesia adopt the DART II system, but we also
propose that a regional tsunami warning center is established in each of these
countries, as well as a buoy system. The buoy sensor will communicate to the
regional tsunami warning  center via radio and satellite while, the buoy will
also report to the International Tsunami Warning Center via Satellite.  The
international tsunami warning center, which is located in Hawaii, will receive
data from all of the buoys around the world. They will warn regional tsunami
warning centers in the case of a tsunami.  Thus, we propose a nearly fail safe
communications network with direct communication from regional buoy to both
regional and international warning centers via sattellite and in the case of
regional-regional , via radio. Thus in the event that one of the warnign
centers or regional buoys are not working properly, the international warnin
center can issue the warning for that country intime to save people's lives.
        Peru, already has a buoy sensor in place as well as a tsunami warning center.
The problem with Peru's tsunami warning center, is that it is run and managed
by its Navy. On the other hand, Micronesia has yet to have a regional buoy, or
a tsunami warning center. Funding, building and management for its warning
center is a problem that our class would have to address.

Bibliography

My Annotated Bibliography

1. Peru's Tsunami warning Center Website

Sources quoted directly

Photo Credits

Graphic for banner on this page from http://www.noaa.gov/tsunamis.html

Page last updated by your-username at 10/31/2005 2:43:16 PM Timestamp