Seismic and Tsunami Hazard in Sulawesi island

Seismic and tsunami Hazard (Sulawesi island)

TOPIC    : SAFETY IN THE FIELD (Prevention & Mitigation of Risk Tsunami Disaster)

Date/Time    : 20 October 2014

By                 : I Made Utarka

I. The concept note covers the following topics: 

1.Tsunami characteristics,

2.Do or Not to Do in pre, during, and post-tsunami time phases ,

3.Tsunami risk in Indonesia and its assessment in any given area,

4.Multi-hazard situation in coastal regions of Indonesia and mitigation measures ,

5.Specific design solutions against various tsunami effects ,

6.Warning systems and communication,

7.Institutional arrangement and design criteria

What is a tsunami?     Tsu = pelabuhan ; nami = gelombang

A tsunami is a series of waves with a long wavelength and period (time between crests). Time   between crests of the wave can vary from a few minutes to over an hour. 

How are tsunamis generated? 

•Tsunamis are generated by any large, impulsive displacement of the sea bed  level.

• Earthquakes generate tsunamis by vertical movement of the sea floor. If the sea floor movement is horizontal, a tsunami is not generated. Earthquakes of M > 6.5 are critical for tsunami generation.

•Tsunamis are also triggered by landslides into or under the water surface, and can be generated by volcanic activity and meteorite impacts

How big is a tsunami? 

•Tsunamis range in size from centimeters to over 30 m height. Most tsunamis are less than 3 m in height.

• In deep water (greater than 200 m), tsunamis are rarely over 1m high and will not be noticed by ships due to their long period (time between crests).

• As tsunamis propagate into shallow water, the wave height can increase by over 10 times.

• Tsunami heights can vary greatly along a coast.  The waves are amplified by certain shoreline and bathymetric (sea floor) features.

• A large tsunami can flood land up to more than 1.5 km from the coast.

   The force of some tsunamis is enormous. Large rocks weighing several tons along with boats and other debris can be moved inland hundreds of feet by tsunami wave activity. Homes and other buildings are destroyed.

PLTD 10 MW dihanyutkan Tsunami sejauh 4km ke daratan , beratnya sekitar 5000 ton

                                         Tsunami Dec 2004 Aceh

                                   1833 Sumatra Tsunami                                  2004 Tsunami


WHAT TO DO OR NOT TO DO UNDER RISK FROM TSUNAMI
(Apa yang dilakukan dan tidak  dilakukan dalam keadaan bahaya karena Tsunami)

—You should find out if your home, school, workplace, or other frequently visited locations are in tsunami hazard areas.

—Know the height of your street above sea level and the distance of your street from the coast or other high-risk waters.

—Evacuation orders may be based on these numbers.

—Plan evacuation routes from your home, school, workplace, or any other place
you could be where tsunamis present a risk.

—If possible, pick areas (30 meters) above sea level or go as far as 3 kilometers inland, away from the coastline.

—You should be able to reach your safe location on foot within 15 minutes

—Be prepared to evacuate by foot if necessary

—If your children's school is in an identified inundation zone, find out what the school evacuation plan is.

—Find out if the plan requires you to pick your children up from school or from another location.

—Practice your evacuation routes. (Praktekan jalur evakuasi anda)

—Familiarity may save your life.  (Dengan memahami semua mungkin akan menyelamatkan nyawa anda)

—Use a Weather Radio or stay tuned to a local radio or television station to keep informed of local watches and warnings.  (gunakan radio yang menyiarkan ramalan cuaca, radio lokal atau televisi untuk menjaga tetap mendapat informasi terakhir kondisi peringatan setempat)

—Talk to your insurance agent. (Bicarakan dengan agen asuransi anda)

—Homeowners' policies may not cover flooding from a tsunami. Ask about the Flood Insurance Program.  (Kebijakan pemilik rumah mungkin tidak mengcover banjir karena tsunami, Mintalah programasuransi karena banjir)

—Discuss tsunamis with your family. (Diskusikan Tsunami dengan keluarga anda)

—If you are visiting an area at risk from tsunamis

        Check with the hotel, motel, or campground operators for tsunami evacuation information and find out what the warning system is for tsunamis. It is important to know designated escape routes before a warning is issued.

Pontensi Tsunami di Indonesia (source : website BMKG)
Indonesia merupakan negara yang rawan terhadap tsunami, terutama kepulauan yang berhadapan langsung dengan pertemuan lempeng Eurasia, Indo-Australia dan Pasifik, antara lain Bagian Barat P. Sumatera, Selatan P. Jawa, Nusa Tenggara, Bagian Utara Papua, Sulawesi dan Maluku, serta Bagian Timur P. Kalimantan



Peta Tektonik dan Gunung Berapi di Indonesia. Garis biru melambangkan batas antar lempeng tektonik, dan segitiga merah melambangkan kumpulan gunung berapi. Sumber: MSN Encarta Encyclopedia

TSUNAMI WARNING AND COMMUNICATION SYSTEM 

—International Status of Tsunami Warning and Communication System

—Tsunami Warning System is based on the concept that Tsunamis travel at much slower velocity (500 to 700 km per hour or 0.20 km/sec) as compared to seismic waves (6 to 8 km per second).

—after the occurrence of a damaging earthquake and quick determination of epicenter, warning time of a few minutes to 2 to 3 hours is available depending upon the distance from the epicenter to the coast line

—PTWS (Pacific Tsunami Warning System) -26 Int’l member state, the TWS center in Ewa beach-Hawaii,  has the following components: 

—Seismometers including ocean bottom seismometers

—Tide gauge stations/Seal level recorder.

—Pressure recorder in the ocean bottom by moored systems

—Satellite based communication links.