Tsunami...... Tsunami..... Tsunami.....

Base on tsunami historical, Tsunami disaster can make destroy and loss material of every place who get tsunami wave inundation. A Tsunami is a seismically generated gravity waves, characterised by wave periods that are in the order of minutes rather than seconds. Tsunami are sometimes referred to as tidal waves, a term that has fallen out of favor, especially in the scientific community, in recent years because tsunami actually have nothing to do with tides. The once popular term derives from their most common appearance, which is that of an extraordinarily high incoming tide. Tsunami and tides both produce waves of water that move inland, but in the case of tsunami the inland movement of water is much greater and lasts for a longer period, giving the impression of an incredibly high tide.


It is very danger for many peoples in coastal area and arround coastal zona. Tsunami disaster also can make many victims and peoples be dead. The cities who have high vulnerabilty zone of tsunami disaster, they have to make mitigation planning for prevent and recovery many loss material and peoples death. For indonesia people, tsunami disaster is very familiar in their live. From 1900 until 2006 was happen more than 19 tsunami disaster. From this case 15 tsunami disaster occured in the eastern part of indonesia which we knew in this areas also we called very active and complex seismotectonic zone. Tsunami wave in Aceh (26 December 2004) caused many people be dead. In 2006, Tsunami also occured in Pangandaran, Cilacap and Kebumen. It make conclusion that Indonesia have high susceptibility of tsunami disaster.



by: Ratih Fitria Putri (Double Degree Master Program MPPDAS GMU - Remote Sensing Chiba University Japan)

Tsunami Hazard.... Causing by Earthquake??

What is a tsunami?
The official definition of a tsunami is: “a wave train, or series of waves, generated in a body of water by an impulsive disturbance that vertically displaces the water column”.

What causes a tsunami?
In general, anything that is capable of moving large water masses can cause a tsunami. Various sources as earthquakes, landslides, volcanic eruptions, explosions, and even the impact of cosmic bodies, such as meteorites, can generate tsunamis.

Shallow water waves
A tsunami is what we call a shallow water wave. A wave is a shallow water wave if the wavelength of the wave is much longer than the depth of the water the wave is traveling through. This is typically the case for tsunamis which have wavelengths exceeding 100 km while traveling through 5-7 km deep water. Because the rate at which a wave loses its energy is inversely related to its wave length, tsunamis not only propagate at high speeds, they can also travel great, transoceanic distances with limited energy loss (the rate at which a wave loses its energy is inversely related to its wave length).

This explains why the coast of Africa was still hit by a tsunami that originated over 5000 km away. Shallow-water waves move at a speed that is equal to the square root of the product of the acceleration of gravity (9.8 m/s/s) and the water depth - in a 6 km deep ocean a tsunami propagates with 875 km/hr, as fast as an airplane!

Difference between tsunami in the deep ocean and a tsunami approaching the coast

A tsunami behaves fundamentally different in the open ocean and close to the coast in shallow waters (Figure 2). A tsunami in the deep ocean has very long wavelengths and very low amplitude. Approaching the shore the tsunami will slow down in speed and amplitudes will increase dramatically. This is due to the fact that the tsunami’s energy . ux, which is dependent on both its wave speed and wave height, remains nearly constant. Consequently, as the tsunami’s speed diminishes as it travels into shallower water, its height grows. Because of this shoaling effect, a tsunami, imperceptible at sea, may grow to 10-50 meters near the coast.

The probability of tsunami hazard is assumed same as earthquake because it will happen when earthquake occur. But probability for landslide is higher than others because not only earthquake and tsunami that is causing landslide but also precipitation too (hard rain). In this case, we assumed that high rainfall also happen when rainy season. As we know, Indonesia has two seasons in one year those are dry season and rainy season. It means the probability of landslide hazard is 1 time per year (in rainy season) so the value is 1 (one).

Tsunami effects:
There are several speci. c characteristics related to tsunamis that make it clearly distinguishable from other types of waves and that are the cause for the devastating force a tsunami might have:
* Tsunamis can appear as a falling or rising tide, waves or bore
* Tsunamis can last for several hours.
* A tsunami consists of several wave trains following each other.
* A pattern of high water levels is alternated with low water levels



Created by: ratih_nabila as Individual Assignment Double Degree Environmental Remote Sensing GMU-CU, 2009.

Tectonic Earthquake.... and Subdaction Boundaries...

TECTONIC EARTHQUAKES??

Tectonic earthquakes will occur anywhere within the earth where there is sufficient stored elastic strain energy to drive fracture propagation along a fault plane. In the case of transform or convergent type plate boundaries, which form the largest fault surfaces on earth, they will move past each other smoothly and aseismically only if there are no irregularities or asperities along the boundary that increase the frictional resistance.

Most boundaries do have such asperities and this leads to a form of stick-slip behaviour. Once the boundary has locked, continued relative motion between the plates leads to increasing stress and therefore, stored strain energy in the volume around the fault surface. This continues until the stress has risen sufficiently to break through the asperity, suddenly allowing sliding over the locked portion of the fault, releasing the stored energy. This energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface, and cracking of the rock, thus causing an earthquake. This process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as the Elastic-rebound theory.

It is estimated that only 10 percent or less of an earthquake's total energy is radiated as seismic energy. Most of the earthquake's energy is used to power the earthquake fracture growth or is converted into heat generated by friction. Therefore, earthquakes lower the Earth's available elastic potential energy and raise its temperature, though these changes are negligible compared to the conductive and convective flow of heat out from the Earth's deep interior.


SUBDACTION BOUNDARIES

These occur where either oceanic lithosphere subducts beneath oceanic lithosphere (ocean-ocean convergence), or where oceanic lithosphere subducts beneath continental lithosphere (ocean-continent convergence). Where the two plates meet, an oceanic trench is formed on the seafloor, and this trench marks the plate boundary. When two plates of oceanic lithosphere run into one another the subducting plate is pushed to depths where it causes melting to occur. These melts (magmas) rise to the surface to produce chains of islands known as island arcs.

A good example of an island arc is the Western part of Sumatera and Southern part of Java Island. When a plate made of oceanic lithosphere runs into a plate with continental lithosphere, the plate with oceanic lithosphere subducts because it has a higher density than continental lithosphere. Again, the subducted lithosphere is pushed to depths where magmas are generated, and these magmas rise to the surface to produce, in this case, a volcanic arc, on the continental margin.

Created by: Ratih Fitria Putri (Magister Program Double Degree UGM - Chiba Univ)

Sea Level Rise??... Our country Need Coastal Management...

SEA LEVEL RISE???

Numerous options have been proposed that would assist island nations to adapt to rising sea level.
As last week tides burst through sea walls, briefly cutting a key access road to Jakarta’s international airport, some predictions for Indonesia if sea levels rise, From the UN climate change conference on Bali:
• Jakarta airport to be under water by 2035.
• about 25% of Jakarta will vanish by 2050.
• Surabaya and Semarang will be almost permanently flooded by 2080.
• the capital will have to be moved to Bandung.
• 2,000 islands will be lost by 2030.
• 400,000 sq km of land mass lost by 2080, including about 10% of Papua, and 5% of both Java and Sumatra (on the north coast).

Says Nicholas Stern, author of the Stern Report on climate change (2006):
Island states are very vulnerable to sea level rise and very vulnerable to storms. Indonesia is particularly vulnerable.

Environment Minister Rachmat Witoelar raised fears of chaos:
Tens of millions of people would have to move out of their homes. There is no way this will happen without conflict. The cost would be very high. Imagine, it’s not just about building better infrastructure, but we’d have to relocate people and change the way people live.
According to a U.N. climate report, temperatures are likely to rise by between 1.1 and 6.4 degrees Celsius (2.0 and 11.5 degrees Fahrenheit) and sea levels by between 18 cm and 59 cm (seven and 23 inches) within this century.

Based on research sea levels estimation would rise by an average of 0.5cm a year until 2080, while the submersion rate in Jakarta, which lies just above sea level, would be higher at 0.87 cm a year.
Indonesia would become poorer due to loss of islands, because access to mineral resources would become more difficult, or impossible, he said, with 5% being shaved off annual GDP, before even taking into account the loss of property and jobs as millions move from low-lying coastal areas to cities and towns on higher ground.

An IIED study said that there are about 42 million people in Indonesia living in areas less than 10 meters above the average sea level, who could be acutely affected by rising sea levels.
A separate study by the United Nations Environment Programme in 1992 showed in two districts in Java alone, rising waters could deprive more than 81,000 farmers of their rice fields or prawn and fish ponds, while 43,000 farm labourers would lose their job.

Study on mean sea level (MSL) rise has been done on tide data at some locations in the Western Indonesia. To account the effect of climate change, air temperature analysis from some weather stations are also performed. The results showed that air temperature has changed between 0.0 to 0.44 °C per ten years. The sea level analysis showed that mean sea level at Western Indonesia rise between 3.10 to 9.27 mm per year. Based on the results, the prediction on mean sea level change in the years of 2000, 2030, 2050 and 2100 for Cirebon location are 17 cm, 39 cm, 55 cm, and 92 cm, respectively.

The world is irrefutably warming and the panel predicted a rise of 1 to 3 degrees Celsius over the next century that could lead to the inundation of coasts and islands inhabited by millions of people all over the world including Jakarta.

Sea-level rise is not the only threat to the vulnerability of Jakarta due to the climate change. February's floods in Jakarta which inundated more than 70 percent of Jakarta and sent about 450,000 fleeing their homes is strong evidence that torrential rain could be a serious threat for Jakarta. Bigger storms make Jakarta which lies in the lowlands, near the sea, and is crossed by 13 rivers flowing down from the south even more vulnerable.

By: Ratih Fitria Putri

Landslide Hazard Analysis in Blukar, Bodri, and Blorong Watersheds; Central Java, Indonesia

The occurrences of natural disasters in Indonesia which have increased recently caused enormous destruction and human suffering. Environmental degradation, that is often caused by human activities can increase the vulnerability to natural hazards and worsen the consequences. The more human induces the hazard-prone area, the more probability of disaster will affect the human life. The lack of actions to anticipate and mitigate the potential damages also makes it worse.

The on-going soil erosion and exploitation of forest land is causing damage to environment. So the land evaluation is needed for information of sufficient detail to make possible the implementation of a land use priority planning. General purpose land evaluation represents a standardized approach for all lands to evaluate their capability to support a generally defined land use. Land evaluation is a tool for watershed planning. The focus of the land evaluation is to assess the requirements of each type of land use and compare these with the properties of different types of land. The results are several types of alternative uses for each type of land. One of land evaluation is land capability classification. It has a place in farm and catchment level planning. It is based on measurements of permanent physical characteristics of the land. Blukar, Bodri, and Blorong Watersheds are located in some regencies in Central Java Province; mostly in Kendal and the rest in a part Temanggung, Wonosobo, and Semarang Regencies and Semarang City. The following picture is a map to describe where the study area is located exactly.

The study area is susceptible for landslide hazard. The landslides caused damages of facilities and environment, and lost of human life. Inventory data of landslide is needed to prevent damages in that area. The location where the research will be conducted has prone hazard area such as erosion and landslide. If land use is unsuitable with conservation, it will cause hazard. Landslide like erosion has important role in land capability technique in this case. Determination of land capability based for land use priority in that area. The study area, Blukar, Bodri and Blorong watershed, covers an area of approximately 131106,2 ha. Several regions in this watershed is susceptible for landslide hazard. Land capability information only will be no sufficient in that area. It should be integrated with landslide hazard information.

The identification of present landslide mitigation types and strategies done by the communities and local government in the area of study is based on the observation during the field work and interviews.
The identification of types of landslide mitigation strategies performed by the local people in the area of study is based on the observation during the field work and interviews the victims. According to the results of interviews with the landslide victims, before the landslide happened, they were not aware living in a landslide prone area, but after land sliding took place they became aware that they were living in the landslide prone area, especially in the rainy seasons. Based on the interview, there is only one mitigation strategy to avoid landslide, which is by evacuating all the members of the family (house) during the heavy prolonged rainy day or rainfall, especially in the night, to the their neighbourhood which considered as safer area than their house/area.

As regards to the landslide hazard problems in this study area, the mitigation strategy have been performed by local government, which is socialization and warning about landslide hazard through announcement letter from the district government to the head of villages, then the head of villages will issue to the communities, this statement annually declares in the beginning of the rainy seasons. Nevertheless, after the landslides occurred in this area, in the year 2000, the relocation strategy was done by the government.


By: Ratih Fitria Putri (Candidate Double Degree Master Program of International Programe MPPDAS-UGM & Remote Sensing Chiba University)

Institutional and Policy Analysis of Bantul Regency

Coastal Management??

Coastal management initiatives are usually a response to a demand to resolve problems such as conflicting uses of coastal resources, urbanization, access, pollution and environmental degradation. Problems may also be related to poor connection or inefficient coordination between those responsible for making decisions on the allocation of coastal resources; or they may even be a perception among decision-makers that a problem does not exist. A sound understanding of such issues is integral to planning an effective approach to coastal management. It is important that issues be addressed in a coordinated and integrated framework – a feature of good coastal planning. Such a framework ensures that individual issues are recognized, yet enables solutions to be developed that cut across as many issues as possible while avoiding the creation future issues.

RPJM of Bantul Regency

If we see the document of RPJM Bantul Regency we will find a series data that used to be analyzed before some products of planning were resulted. The data that are required in producing RPJM such as Social and Economic data, Demographic data (structure, growth, distribution and trend), Potency of Natural resources (land and its potency, ownership, and its distribution), Forest status, distribution and its potency), Mining (rights, potency and distribution) as well as water resources including (rights, potency and its distribution). Some of the coastal information is available such as the land use and potential tourism area. But there still some lack information which is important for conservation. The information for resident wood need for living in the area not mentioned, thus information can be used for planning allowed wood cutting in the area to maintain the standing stock of plantation for conservation purposes. Beside of the excess, this document still needed better analysis in this several sector :
1. Disaster management data analysis
2. Remote Sensing Application Data Analysis for Coastal area.

The other data are artificial resources such as transportation infrastructure, telecommunication, electricity and power plant, urban utility, as well as clean water. In addition data-data about earth surface condition such as morphology, geology and climate condition. To make comprehensive data-data of previous planning document were also considered. Generally, this document covers all sector, also the RPJM is suitable with higher level (RPJP). There are integrated development explain in document, both marine and land development plan.

Base on these document plan, we can learn about what is a planning, as follow : style of planning, process of planning, product of planning, and actor who involve on planning process, data and information, analysis,and quality of project plan. The term of planning is so many, Diana Conyers & Peter Hills (1984) says, planning is a continues process which involves decisions, or choices, about alternative ways of using available resources, with the aims of achieving particular goals at some time in the future, and Dror (1973) talk about planning is the process of preparing a set of decisions for action in the future, directed at achieving goals by preferable means. Planning have four element: making decisions, allocating resources, achieving goals, and for the future.



Created by: Ratih Fitria Putri (Double Degree Master Program MPPDAS GMU - Remote Sensing Chiba University Japan)