November Sharing Session: Tangkuban Parahu, Kawan Atau Lawan?
The sharing session was conducted on the 9th of November in the Auditorium of the Geology Museum in Bandung and was open to the public in general. Before the start of the sharing session, a video about the Kars Rajamandala area by the Board of Geology was shown to the audience. Fossils and pre-historical records have been found in Gua Pawon, one of the caves in the area. However, the area is being threatened by mining activities around it. The video shows just how important the area is and that we should mitigate its threats to preserve it.
The sharing session started with an introduction of BDSG and what we do, which is to Learn, Share, and Volunteer. We explained our activities such as sharing sessions, school sessions, DRR-Young Exchange Program, and Campaigns, as well as our upcoming activities. After that the audience was asked to participate in an ice breaking game which is called the Bosai Duck, which is also a game that is used as a teaching method about disaster response to schoolchildren in Japan
The main session was a presentation and discussion by Bpk. Adjat Sudrajat, moderated by Pak Hawe entitled Tangkuban Parahu: Friend or Foe? He started by explaining that Indonesia is home to 13% of the world’s volcanoes, which is the largest percentage in the world. Indonesia is home to about 130 volcanoes. Volcanoes such as Gunung Merapi are a window into the earth’s core, which is always erupting. Tangkuban Parahu was created from the massive crater formed by the eruption of Gunung Sunda. Tangkuban Parahu is named so due to its shape formed by it’s many craters lining up, which is similar to a boat which is turned over. Located in the north, Tangkuban Parahu is sometimes active and sometimes not, however Tangkuban Parahu falls into the category A of volcanoes so it should always be monitored due to having eruptions recently. Class B volcanoes rarely erupt, although class B volcanoes can become class A’s. Class C volcanoes do not erupt anymore and is dormant. This classification was made to make monitoring volcanoes easier.
Earthquakes and volcanoes come hand in hand. Volcanical eruptions always happen in a fixed area so a hazard map for potential volcanical eruptions can be made, however earthquakes are difficult because it moves from place to place. There needs to be an evacuation plan for earthquakes as well as the construction of earthquake-proof housing. For volcanoes, material from vertical eruptions include of bomb (large rocks), lapilli (small rocks like pebbles), as well as sand. Eruptions that do not go upwards happen when the material inside the volcano is too heavy while the pressure is small which results in a pyroclastic flow. What we usually call lava is deposits from the flow which have been cooled by rain. Wind also factors into an eruption’s result. The pyroclastic flow ‘s direction can be determined from the lava flow. Lava shines in the night and cools into stone in the day. Lava is made of melted stones and rocks. Lava is material from the eruption mixed with water. Hot lava is formed after rain with a temperature of 30-40 degrees celcius, while cold lava is before the rain. Tangkuban Parahu is measured by seismic indicators, while for Merapi it is the dome and seismic.
Despite their hazards and dangers, volcanoes have a positive side to them. Volcanic earth is very fertile, and is good for growing many things. The geothermal heat near volcanic areas is also good to generate electricity. However, people should also be wary of other things such as CO2 gas which is deadly if inhaled too much and invisible. The good thing is people should not worry as Bandung is supported by the Lembang fault so it is safe from an eruption by Tangkuban Parahu.
The session was followed by the discussion session. The first question was by Lex from ITB on how the Lembang fault would have and effect on Tangkuban Parahu’s volcanic activities. The answer is that earthquakes can affect volcanic activity. However, the Lembang fault also mitigates an eruption by blocking the pyroclastic flow. The second question was from Lutfi of ITB, who asked about the cause of Tangkuban Parahu’s activity. The third question was from Damar of UPI, who asked about the radius of the explosion. The lava would depend on the rain, but the eruption would cover an area of 7 kilometers, while the lava could reach hundreds of kilometers. Dityo from BDSG asked a question about which organizations were responsible for the management of Tangkuban Parahu. The answer is the Depeartment of Forestry, those who manage the area, the government of Subang, and the government of Bandung, coordinated by the BNPB. Bowo from UNPAD asked a question regarding the many high-rise buildings and what should be done in the case of an explosion. There should be information and instructions on where to evacuate, as well an assembly point. Priba from BDSG asked a question on how to manage the many settlements north of the Lembang fault and Tangkuban Parahu’s eruption period. The answer is education about the fault because it is part of the danger zone. Tangkuban Parahu has an active cycle of 3-5 years. Each volcano has different activities so you can’t rely on statistics, especially when eruptions happen very rarely. But usually every 3-5 years when there is enough steam there will be a small eruption at Tangkuban Parahu.
Setiawan from UPI asked a question on how to minimalize the potential threat and what mitigation before and after the disaster can people do. There is a cycle of managing disasters from pre, during, and post. Education and readiness, mapping zones of danger before disasters, readying health supplies and food during disasters, and rehabilitation post disasters. He also asked on whether there is an area which is safe from hazard permanently and whether there can be any changes in danger zones. Some areas are safe permanently because the risk has been calculated to include margins of error. However, the threat of smoke is still possible depending on the wind. Bandung is safe from eruptions and is located in a safe zone. Rifa from BDSG asked a question on whether there is an action plan should an eruption happen on Tangkuban Parahu. The answer is yes, there is an SOP and action plan, it just needs to be socialized repetitively. Januar from ITB asked a question on how should the presence of influential local leaders be put into consideration in mitigation. There needs to be a psychological approach when there is a difference in opinion between the government and local powers, for instance the sultanate of Jogja and the central government (in this case BNPB). A mapping of the area’s social conditions is needed through the help of local leaders. You have to know the characteristics of the people in that area. In the end, the conclusion is that if we realize that volcanoes can surprise us and that we have to be ready, volcanoes can be our friend despite potentially erupting. Humans must be able to live in harmony with volcanoes as a part of nature.