Tsunamis

Wave Speeds and Heights

In Indonesia, it is expected that waves could reach a height of 50 feet and affect land as high as 35 meters above sea level. The waves can move at a speed upwards of 800 km per hour (500 miles per hour)1 and while the first one will be strongest, there could be as five to seven waves in total. Below you will find images for the following areas of Indonesia which show projected wave heights and/or wave speeds as well as inundated population (flooded areas): Bali, Denpasar Bali, Angung City, Bandar Lampung, Bintuhan Sumatra, Southern Sumatra, Cicacap Java, East Java, East Timor Leti Islands, Labuhan, Lombok Kuta Beach, Lombok Mataran City, Pelabuhan Ratu, Sumba, Waingapu Sumba, Sumbawa West Nusa Tenggara, Teluk Lada, West Java, and West Timor.

Below is a series of images for various areas of Indonesia which show projected wave heights and/or wave speeds as well as inundated population (flooded areas and number of people impacted). These images were created by Mr. Bryce Berrett of Brigham Young University.

Note: You can click the images to obtain larger versions.

Bali full rupture map without offshore
BaliFullRuptureNoOffshore1-400.jpg

Bali full rupture map with offshore
BaliFullRuptureWithOffshoreFinal-400.jpg

Java Trench full rupture inundation overview map
Java%20Trench%20Full%20Rupture%20Inundation%20Overview%20Map-400.jpg

Sumatra-Sumba full rupture inundation overview map
Full%20Rupture%20Inundation%20OffshoreOn-400.jpg

Wave Height and Inundated Population Images by City

Agung Sumatra
AngungCity1-400.jpg

Bandar Lampung Sumatra
Bandar%20Lampung-400.jpg

Bintuhan
Bintuhan2%20Sumatra-400.jpg

Cilacap
Cilacap%20Full%20Rupture%202Fix-400.jpg

Denpasar
Denpasar-Kuta%20Bali%20Sarah%20Paper%20Labeled%20(less%20MB)-400.jpg

Kencong Lodjedjer
Lodjedjer%20Kencong%20Full%20Rupture%20Flow%20Depth%202-400.jpg

Kuta Lombok
Kuta%20Beach%20Flow%20Depth%20Contour-400.jpg

Labahan
Labuhan-400.jpg

Mataram Lombok
Mataram%20City%20Flow%20Depth-400.jpg

Pacitan
Pacitan%20Full%20Rupture%20Flow%20Depth2-400.jpg

Pamenang Lombok
Pamenang%20North%20Lombok%20Flow%20Depth%20with%20contour-400.jpg

Pangadaran
Pangadaran%20Full%20Rupture%20Flow%20Depth1-400.jpg

Pelebuhan Ratu Java
PelabuhanRatu3TransInset-400.jpg

TelukLada Java
TelukLada1-120000TimeSeriesX2-400.jpg

Waingapu Sumba
Waingapu%20Flow%20Depth%20Transparent%20Contour-400.jpg

Things to Consider

Before the tsunami strikes, however, those on land will be impacted by the earthquake which caused the tsunami. For this, significant shaking may be felt many meters in land.

Based on this, there are two types of building risk we need to consider. First, is the earthquake; second, is the tsunami. The earthquake is what causes the tsunami but also affects land and structures independently before the wave impact. Then, after the earthquake has begun impacting buildings and structures, the initial wave of the Tsunami hits. This is followed by additional waves and earthquake aftershocks. Any given location should expect between five and seven waves. While the force and speed may be less with each additional wave, the distance in-land reached (inundation distance) and the height above sea level which is impacted (run up elevation) will increase.

Tsunami Impact

Tsunami waves are very different from tidal waves. A tidal wave is by definition a wave caused by ocean tides, whereas a tsunami is almost always caused by an earthquake under water. See http://www.sms-tsunami-warning.com/pages/tsunami-features#.WXRtXIjyvic for additional information and images.

The effect of a tsunami is defined by several factors: height, run-up height and run-up distance. The large amount of water that a tsunami pushes onto the shore above the regular sea level is called run-up, that is the maximum vertical height onshore above sea level reached by a tsunami. Run-up is the more damaging force than the huge tsunami waves as it surges inland and destroys all in it's path. The first wave in a tsunami train doesn't always produce the highest run-up. Scientists have tried to explain why and found that a tsunami’s frequency (that is how closely in time one wave follows another) combined with a shoreline’s slope can result in a resonance that sends more water onshore2

See http://www.sms-tsunami-warning.com/pages/runup-inundation#.WXRvcojyvid for additional information and images.

Local topography and directional travel have a great influence on the run-up effect of earthquake generated tsunamis. In Japan the run-up factor was 10 but can be as much as 25. Run-up factors of 40 have been observed in Hawaii3.

References

1 http://ptwc.weather.gov/faq.php
2 http://www.sms-tsunami-warning.com/pages/runup-inundation#.WXRshYjyvic
3 http://www.sms-tsunami-warning.com/pages/runup-inundation#.WXRvcojyvid

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