VERY LOCAL TSUNAMI WARNING SYSTEM ANOTHER CHALLENGE OF INATEWS

The establishment of the tsunami warning system is based on the fact, that the seismic waves propagate faster then tsunami wave. The tsunami wave arrive in the shore line after the earthquake parameters can be determined, so that there is time left to evaluate the earthquake, whether the earthquake is tsunamigenic or not, disseminated the information or warning to the target area, and finally to do evacuation if necessary. For the tele-tsunami, in which the tsunami will arrive in the beach more then one hour after the origin time of earthquake, generally there is enough time to do all of those processes, so that the warning can be disseminate in 100 % confidence level. For local tsunami, in which the tsunami will arrive in the beach less then one hour, the warning is disseminated in the lower the confidence level. For example, Indonesia Tsunami Warning System (InaTEWS) is designed for local tsunami warning for Indonesian region. Any tsunami-genic earthquake occurs in the Indian Ocean plate boundary, the tsunami wave will sweep the closest shore line within 20-40 minutes after the origin time of the earthquake. The warning is determined just only based on the evaluation of the earthquake parameters and tsunami modeling. It is difficult to add sea level data to increase the confidence level of he warning. Although the confidence level is lower, the tsunami warning could be disseminated. In some cases, especially for the eastern of Indonesia, the tsunami can be generated within inner sea, such as Flores sea, Banda sea, Ceram sea, Maluku sea, and any others. In that cases, tsunami wave will reach the closest shore line within 10 minutes or less. This tsunami may be called as very local tsunami. By evaluating the time line for issuing the tsunami warning, it is clear that very critical to disseminate tsunami warning based on the available technology recently. The effectiveness of the warning is very small, therefore another possibility warning for very local tsunami should be designed. In this presentation, we propose to use natural signs as the warning. As we might know that in general tsunami can be generated by large earthquake.

This kind earthquake could be felt strongly by most peoples. This natural sign could be applied as a tsunami warning. The other possibility is to use rather simple technology, as compliment to the natural warning. A very local tsunami warning system can be designed as the following. The warning system consist of two devices, those are a three component broadband seismograph and a local siren. The seismograph can be used to monitor and estimate the magnitude of the local earthquake and the siren can be used to warn the people if the earthquake is possible to generate tsunami.
Although, the natural signs and the simple technology could be combine to establish the very local tsunami warning system, the important is to educate people so that they understand the earthquake,tsunami, and how they can save from those disasters
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ANALISA SEISMOTEKTONIK DAN SEISMIC RATE CHANGES WILAYAH SUMATERA, STUDI KASUS GEMPA BENGKULU 2007 DAN PADANG 2009

A mid-term precursory seismic rate changes before 2007 Bengkulu earthquake and 2009 Padang earthquake was observed. We focused in this study on analyze seismotectonic parameter and seismic rate changes over Sumatra using Matlab. Seismicity rate changes parameter is used to identify mid-term precursor. We use the catalogue of USGS and BMKG from 1973.03 up to 2009.69. From seismicity rate changes anomaly, earthquake precursor can be identified 3-1 years before M8.5-M7.9 (USGS) 13 September 2007 Bengkulu earthquake and 6-3 years before M7.5 (USGS) 30 September 2009 Padang earthquake. From seismotectonic analysis, the period of repeated earthquakes in the Sumatra region with magnitudes M6,5 varies between 5 to 22 years and M7 varies around 15 to 90 years


Pendahuluan
Sumatera-Andaman merupakan salah satu wilayah dengan aktifitas kegempaan yang sangat tingi. Salah satu gempa terbesar di dunia Mw 9,0 pernah terjadi di wilayah ini pada 26 Desember 2004, disusul gempa nias Mw 8,7 pada 28 Maret 2005. Para ahli seismologi di dunia telah melakukan penelitian-penelitian mengenai proses gempabumi, salah satunya adalah relasi frekuensi-magnitude yang dikemukakan oleh Gutenberg-Richter (1964). Relasi frekuensi-magnitude dari gempabumi, pertama kali dikemukakan oleh Ishimoto and Iida (1939) serta Gutenberg Ricther (1964). Relasi ini merupakan hubungan pangkat (power law). Banyak ahli menyatakan bahwa nilai-b bergantung pada karakter tektonik dan tingkat stress atau struktur material suatu wilayah (Scholz, 1968; Hatzidimitriou, 1985; Tsapanos, 1990). Variasi nilai-b suatu wilayah berhubungan dengan heterogenitas struktur dan distribusi stress wilayah tersebut (Scholtz, 1968; Biswas, 1988). Secara statistik perubahan nilai-b yang signifikan telah teramati di beberapa regime stress seperti zona subduksi lempeng dan zona patahan.

Prekursor seismik merupakan sesuatu hal yang penting meskipun masih menjadi topik yang banyak diperdebatkan sampai saat ini antara yang setuju dan tidak. Salah satu prekursor yang dipelajari saat ini adalah ketenangan seismik (seismic quiescence). Seismic quiescence dikemukakan pertama kali oleh Wyss dan Habermann (1988) dengan hipotesanya bahwa beberapa gempa utama diawali dengan kehadiran seismic quiescence dimana terjadi penurunan yang signifikan dari rata rata tingkat seismisitasnya.
Penelitian ini bertujuan menganalisa prediktabilitas gempabumi dalam skala waktu menengah di daerah Sumatera menggunakan metode perubahan tingkat kegempaan dengan mengambil studi kasus gempa gempa besar yang terjadi di wilayah Sumatera pada tahun-tahun terakhir ini antara lain gempabumi Bengkulu 13 September 2007 dan gempabumi Padang 30 September 2009.
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SITE SURVEY OF SEPTEMBER 30,2009 WEST SUMATERA EARTHQUAKE

On September 30, 2009, at 5:16 PM local time, a 7.6 followed by a 6.2 magnitude earthquake struck off the coast of West Sumatra Province in Indonesia, damaging houses, bringing down bridges and starting fires, a witness said. It was unclear if there were any casualties.The earthquake occurred at 0.84 south latitude location and 99.65 East Longitude. The epicenter was in the 57 kilometers southwest of Pariaman, West Sumatra. The Pacific Tsunami Warning Centre cancelled an earlier tsunami warning. Japan said no tsunami was expected there.

The 7.6 magnitude quake was felt around the region, with some high-rise buildings in the city state of Singapore, 275 miles (440 km) to the northeast, evacuating their staff. Office buildings also shook in the Malaysian capital, Kuala Lumpur. The latest damage report say that earthquake killed at least 809 people.

The investigative itinerary focused on areas with local reports of damage, including the cities of Padang and Pariaman.


To be continued...
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SITE SURVEY OF SEPTEMBER 2, 2009 WEST SUMATERA EARTHQUAKE

On September 28, 2009, at 2:55 PM local time, a M 7.3 earthquake struck Tasikmalaya distric, West Java province. Occurring 142 km WSW of Tasikmalaya, Java at a depth of 30km. A tsunami warning was issued but withdrawn one hour later. The main shock and several aftershocks caused 64.413 structures, including houses and bridges, to collapse or suffer significant damage in Tasikmalaya, Cianjur, Garut,Sukabumi,Bandung, West Bandung, Bogor, Kuningan, Ciamis, Banjar, Purwakarta, Majalengka and Subang, which in turn caused at least 82 deaths.


To be continued...
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ADD GTALK TO BLOG

I am sure you certainly knew what is the Google Talk. With Google talk, you can send instant messages, make voice calls, leave voicemail also transfer files etc, but of course must be with the Google users. Now, you can add Google talk to your blog. Please follow the step below :

Login to blogger with your ID.

After entering the dashboard page , click Layout.

Click at Page Element tab.

Click at Add a Page element.

After emerging pop up window , Click add to blog button for the things HTML/JavaScript.

Copy and paste the code below into available column :

<iframe width="234" frameborder="0" src="http://talkgadget.google.com/talkgadget/client?fid=gtalk0&relay=http%3A%2F%2Fwww.google.com%2Fig%2Fifpc_relay" height="350">
</iframe><p style="margin:-8px 0"><br /><center>
<a style="text-decoration:none;font-size:70%;" href="http://rohman-freeblogtemplate.blogspot.com/2008/01/add-google-talk-to-blog.html">Add to your blog</a></center></p>


Click Save Changes

Finish.
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Geophysical Network, Existing And Future Plan

Indonesian Meteorological and Geophysical Agency (MGA) is governmental bodies who responsible to provide data and information of Meteorology, Climatology, Air Qualities and Geophysical phenomena’s. Recently MGA is developing the geophysical networks to improve the capabilities in providing the geophysical data and information services, including the tsunami warning system. In the future, the seismological networks will be enhanced by installing 160 broadband seismographs and real time data processing to support the tsunami warning system. The geomagnetic also will be added up to 8 – 10 station, while the gravity base point will be added to support the gravity surveys for the exploration works. The lightening networks will be
expanded to cover all of Indonesian region.

1. Introduction
The Meteorological and Geophysical Agency (MGA) of Indonesia has fundamental duty to manage and execute task in meteorology and geophysics. Task and function of MGA are providing accurate, prompt, and qualified services for protection of citizen lives and properties from natural disaster. MGA has responsible for policy formulation for standard operational procedures in the fields of meteorology, climatology and geophysics. Implementation of meteorological, climatological and geophysical observation, data processing, analysis and information services in the ocean and in the atmosphere. Mandatory in the operational of meteorology, climatology and geophysics and also authority to announce severe weather warnings and alerts. To take care all of the tasks MGA operates and maintains geophysical stations, including the seismic networks, geomagnetic networks, geomagnetic repeat stations,
gravity base/check point networks and also lightening detector networks. This paper is a brief description of geophysical network running by MGA.


2. Seismological Stations and Networks
Indonesia is located in seismic active region due to the interaction among 3 mega plates namely Eurasia, India Ocean-Australia, Pacific and 2 smaller one Philippine Sea and Caroline. These interactions create regional and local faults that generate earthquakes. So, every time and every place in Indonesia have earthquake potentials. Figure 1 shown seismicity of Indonesia and Indian ocean. Now MGA of Indonesia has 30 geophysical stations and 28 telemetry seismic stations, that record earthquake event from all location in Indonesia and its surrounding. Those geophysical stations send the seismic data to National Seismic Center, MGA Jakarta and to Regional Seismic Center. At present MGA of Indonesia has 5 regional centers, located in Medan, Ciputat, Denpasar, Makasar and Jayapura.


Paper ini dibuat Th 2006, Mohon dimaklumi jika sudah terjadi banyak perkembangan.

Selengkapnya download disini

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Analisa Parameter Sesimik Dan Tektonik Serta Waktu Perulangan Gempa Wilayah Papua

Analisa parameter seismik dan tektonik suatu wilayah merupakan hal yang penting karena perubahan tingkat seismisitas suatu wilayah berhubungan erat dengan perubahan stress dan tekanan bawah permukaan wilayah tersebut. Distribusi frekuensi-magnitudo dari Gutenberg-Richter dinyatakan dalam log N = a - bM, nilai a merupakan parameter seismik yang mencerminkan tingkat seismisitas suatu wilayah pada periode tertentu. Nilai-b merupakan parameter tektonik yang berkaitan erat dengan tingkat stress dan karakter tektonik suatu wilayah. Perubahan nilai-b suatu wilayah dipercaya berbanding terbalik terhadap perubahan tingkat stress wilayah tersebut. Katalog gempabumi NEIC dari tahun 1973-Januari 2009 dipergunakan untuk menganalisa parameter seismik dan tektonik serta waktu perulangan gempabumi di wilayah Papua. Dari analisa parameter seismik dan tektonik di wilayah dengan batas 4° LU - 5° LS dan 129° BT - 137° BT didapatkan variasi nilai b berkisar antara 0,6 sampai 1,6, variasi nilai-a berkisar antara 4,8 sampai 9,2 dan waktu perulangan gempabumi dengan M 6,5 sekitar 6 tahun, M 7 sekitar 12 tahun.

PENDAHULUAN
Indonesia sejak lama dikenal sebagai salah satu wilayah dengan tingkat aktifitas gempa yang tinggi, hal ini dikarenakan letak Indonesia diapit oleh lempeng-lempeng tektonik raksasa yang saling bertumbukan satu dengan lainnya sehingga menempatkan Indonesia pada kerawanan yang tinggi terhadap bencana gempa bumi. Analisa seismisitas pada wilayah aktif gempa telah banyak dilakukan oleh para ahli. Dari analisa parameter seismisitas diketahui bahwa nilai-b merupakan parameter tektonik yang banyak dipercaya bergantung pada tingkat stress dan karakter tektonik lokal. Perubahan nilai-b dipercayai berbanding terbalik dengan tingkat stress wilayah tersebut. Penelitian ini bertujuan untuk menganalisa secara spasial maupun temporal parameter seismisitas dari relasi distribusi frekuensi magnitude serta analisa secara statistik waktu perulangan gempabumi dengan magnitude diatas 6 sebagai salah satu upaya untuk mitigasi gempabumi dan tsunami.

Penelitian ini membahas analisa parameter seismik dan tektonik serta waktu perulangan gempabumi di wilayah papua dengan batas 4° LU - 5° LS dan 129° BT - 137° BT .

Selengkapnya download disini


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Analisa Fraktal Dan Rasio Slip Daerah Bali-NTB Berdasarkan Pemetaan Variasi Parameter Tektonik

Distribusi gempabumi secara tidak langsung dapat dianggap sebagai fraktal, sehingga dapat dicirikan di dalam dimensinya (D), sementara seismisitas dapat dikarakterisasikan oleh parameter tektonik (nilai-b) dan dimensi fraktal (D). Dimensi fraktal memiliki korelasi dengan parameter tektonik (nilai-b) dari relasi distribusi frekuensi-magnitude Gutenberg-Richter log N = a-bM. Analisa fraktal dan slip rasio daerah Bali-NTB berdasarkan pemetaan variasi spasial nilai-b telah dilakukan pada penelitian ini mempergunakan katalog gempabumi dari tahun 1973-Maret 2009. Dari analisa parameter tektonik, dimensi fraktal serta slip rasio di daerah penelitian dengan batas 6° LU - 12° LS dan 114° BT - 121° BT didapatkan nilai-b bervariasi antara 0,7-1,9 dengan nilai-b rendah disebelah selatan pulau sumbawa sekitar pulau sumba serta sebagian daerah disebelah utara pulau lombok sumbawa. Dimensi fraktal pada kluster 1 dan 2 di daerah selatan pulau sumbawa serta sebelah utara pulau lombok sumbawa bernilai sekitar 2 yang mengindikasikan distribusi sumber 2D sedangkan dimensi fraktal pada kluster 3 di daerah sekitar pulau sumbawa bernilai sekitar 3 yang mengindikasikan distribusi sumber 3D. Rasio slip kluster 1 dan 2 berkisar 0,5 yang mengindikasikan sekitar 50% total slip terjadi pada sistem patahan utama (primer). Rasio slip kluster 3 mendekati 0 sehingga semua slip terjadi pada patahan-patahan kecil.

PENDAHULUAN
Daerah Bali-NTB merupakan salah satu daerah dengan tingkat kegempaan yang cukuf aktif karena terletak pada jalur mediteranian. Secara tektonik, busur kepulauan Bali dan Nusa Tenggara berada di antara zona tumbukan lempeng Indo-Australia dengan Eurasia di bagian selatan dan patahan naik busur belakang Bali-Flores di bagian utara. Daerah dengan batas 6° LS -12° LS dan 114° BT - 121° BT ini memiliki karakteristik gempabumi yang beruntun, dimulai dengan gempa pendahuluan, gempa utama dan selanjutnya diikuti oleh gempa-gempa susulan (Sulaiman, R. Dkk, 2002). Distribusi Gempabumi yang terjadi pada umumnya berkedalaman dangkal di bagian selatan sementara distribusi gempa menengah dan dalam tersebar di bagian tengah dan utara dengan magnitude terbesar yang tercatat sebesar 8 yang terjadi pada tahun 1977 pada posisi 118.46 BT dan 11.09 LS.

Selengkapnya silakan download disini


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