National Geophysical Data Center (NGDC)

The National Geophysical Data Center maintains two databases of historic tsunamis. The event database is a searchable compilation of tsunamigenic events dating from 47 B.C. to the present. This database is useful in identifying geologic events (earthquakes, volcanic eruptions, landslides) that potentially generated tsunamis in different ocean basins. The run-up database is a seachable compilation of documented tsunami effects in coastal areas around the world.

Tsunami Laboratory, Novosibirsk, Russia

The Tsunami Laboratory, Novosibirsk, Russia, maintains a database of tsunamis that is very similar to that of NGDC. However, the data are archived in three catalogs separating tsunamis from different geographic areas: The Mediterranean Sea (1628 B.C. to 1999), the Atlantic Ocean (60 B.C. to present), and the Pacific Ocean (47 B.C. to present).

Both online databases perform similarly, so for convenience this exercise will utilize the NGDC databases. Your task is to query the event database to locate tsunamis in Indonesia and Malaysia for the period 1801 to 1900. To do this, go to the event database web site and enter appropriate values in the interactive form spaces. For this exercise, you need only enter a 'beginning year', 'ending year', and 'Indonesia and Malaysia' in the "Source Region" box. Then click the "Search Database" button at the bottom of the page. Once you have submitted your query, in a few seconds your results will be displayed on the screen. These results can be selected, copied, and pasted to a spreadsheet and saved for analysis.

Next, go to the run-up database and enter the same parameters as before. When your data are visible on the screen, select your records, copy and paste them into your spreadsheet. Then manipulate your data to answer the questions below:

1. Which query generated the greatest number of records?
2. Why don't they generate the same number of records?
3. What is the largest magnitude earthquake among your data lists?
4. What is the largest wave height among the tsunamis in your lists?
5. Which tsunami had the highest run-up?
6. Which tsunami generated the greatest number of run-ups?
7. Which tsunami caused the greatest number of fatalities?
8. What was the frequency of tsunamis during the 19th Century? Are you surprised by this value?
9. Of the tsunamis in your list, what percentage have casualty figures associated with them?
10. Sort your data by wave height and fatalities, then plot the data on a scatter plot. Is there a correlation between tsunami height and fatalities? Why or why not?
11. Sort your data by number of run-up events and fatalities, then plot the data on a scatter plot. Is there a correlation between run-up events and fatalities? Why or why not?

In addition to historic tsunami data, there are near-real-time charts from modern tide gauges that recorded passage of the 26 December 2004 tsunami in the Indian Ocean.

National Institute of Oceanography, India

The National Institute of Oceanography, India maintains a network of tide gauges along the Indian coastline. The tide gauges were operating at the time tsunamis made landfall on 26 December 2004 and provide remarkable records of the passage of these waves. Go to the web site by clicking on the link in the preceding sentence. Once at this site, print the tide gauge records and answer the questions below:

1. For each tide gauge station, did the tsunamis first arrive at high tide or low tide?
2. On the day of the tsunamis, what was the apparent tidal range at each site?
3. What was the maximum wave height of the tsunami (as represented on the tide gauge record) at each station?
4. Was the maximum wave height greater or lesser than the tidal range?
5. Do you think tsunamis arriving at high tide did more damage than tsunamis arriving at low tide? Can you think of reason why this might not be so?
6. Search the Internet for information that might help answer question #5 above.
7. How many hours were tsunami waves recorded at each station?

Tide Gauge Records from Dr. John Huthnance, UK

Tide gauge records from several tide gauges in the the Maldives, Diego Garcia, and the western Indian Ocean were analyzed and placed online by Dr. John Huthnance, of the National Tidal and Sea Level Facility, Proudman Oceanographic Laboratory, UK. Access these tide gauge records here, then print each and compare to the records from India. Use them to answer the questions below:

1. For each tide gauge station, did the tsunamis first arrive at high tide or low tide?
2. On the day of the tsunamis, what was the apparent tidal range at each site?
3. What was the maximum wave height of the tsunami (as represented on the tide gauge record) at each station?
4. Was the maximum wave height greater or lesser than the tidal range?
5. Did the tsunamis in the Maldives have larger or smaller wave heights than those along the Indian coast. Can you think of an explanation for this observation?
6. Estimate (as best you can) the arrival time of the first tsunami at each station and compare this arrival time to those of the Indian tide gauges. Use the Internet to find information on the distance separating these tide gauges. Once you have this information, estimate the celerity of the tsunami between sites. Does this value agree well or not with celerities reported on the previous page? Can you think of reasons why this may or may not be so?
7. How many hours were tsunami waves recorded at each station?

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