2. Tsunami Sources
Earthquakes (e.g. Sumatra, 2004: >200,000 people killed; Papa
New Guinea, 1998: ~3,000 people killed)
Volcanic eruptions (e.g. Krakatoa, 1883: tsunamis killed 30,000
people; Santorini, 2002).
Mass Movement (e.g. Alaska, 1958: waves up to 518 m high
formed in Lituya Bay).
Extraterrestrial Impacts - large impacts have the potential to
create enormous tsunamis.
3. Tsunami Earthquakes
Some earthquakes have generated very large tsunamis
for their “size”. These events are called tsunami
earthquakes.
Analysis of seismograms from these events suggest that they
are the result of low-frequency seismic energy.
These earthquakes present a problem for tsunami warning
systems
4. One of the largest earthquakes since seismometer invented ~ 1900
EARTHQUAKE MAGNITUDE 9.3
6. Tsunami Genesis
Tsunamis are
caused by events
that drastically and
suddenly shift a
large volume of
water.
7. An Example
The 2004 Indian Ocean earthquake, known by the scientific community as the Sumatra-Andaman earthquake, was an
undersea earthquake that occurred at 00:58:53 UTC (07:58:53 local time) on December 26, 2004. The earthquake
triggered a series of lethal tsunamis that spread throughout the Indian Ocean, killing large numbers of people. The
magnitude of the earthquake was originally recorded as 9.0 but has been upgraded to between 9.1 and 9.3 Recent
analysis indicates the number of casualties were 186,983 dead and 42,883 missing, for a total of 229,866 affected This
earthquake was also reported to be the longest duration of faulting ever observed, lasting between 500 and 600 seconds,
and it was large enough that it caused the entire planet to vibrate at least half an inch, or over a centimetre
8. Propagation, Response and Warning Times
for the M9.0 Sumatra EQ
10 minutes after OT
Northern Sumatra
Significant structural damage
in Banda Aceh
Tsunami inundation along the
Sumatran coast
EQ is widely felt throughout
the region
NEIC
Short period alarm on eight
stations in the region
PTWC
Short period alarm on western
Pacific stations
P S
Short-period alarm stations
9. IN DEEP OCEAN tsunami has long wavelength, travels fast,
small amplitude - doesn’t affect ships
AS IT APPROACHES SHORE, it slows. Since energy is
conserved, amplitude builds up - very damaging
