What is Mount Merapi?

Mount Merapi is a volcano located on the island of Java in Indonesia. Mount Merapi or ‘mountain of fire’ is part of the ring of fire. Mount Merapi has erupted 68 times since the sixteenth century and is the most active volcano in its region. It is one of 129 active volcanoes in Indonesia making up part of the Pacific Ring of Fire. It is located on the subduction zone of the Indo-Australian and Eurasian plates. It is one of the most active volcanoes in Indonesia and has been erupting frequently since 1548. Since 1920 there have been 10 eruptions that have caused human fatalities. Typically, smoke can be seen emerging from the top of the volcano 300 days in the year.

What type of volcano is Merapi?

Mt Merapi is 9551ft tall and is an active composite volcano and has andesitic lava. It is cone-shaped with a narrow base and steep sides, which are made of alternate layers of lava and ash from previous eruptions. When eruptions occur they are usually violent and lava and ash are present. Until about 10,000 years ago eruptions have been effusive and lava was basaltic. However, now the eruptions have become much more explosive and often generate lava domes. The collapse of these domes has often caused pyroclastic flows and longer explosions.

When did Merapi erupt?

Between 25th-26th October 2010, Mt Merapi erupted three times; thousands were evacuated from a 20km radius around the slopes of the volcano. The column of smoke rose vertically to 1.5km and pyroclastic activity began to subside, 18 people were found dead. The deaths were due to burns and respiratory problems. Between 17th-29th October 2010, the evacuation zone remained, however, lava ejection with hot ash clouds fell down the slope and travelled 3km and pressure seemed to be decreasing behind the lava dome that had formed in the crater. The death toll was now at 30. From the 30th October, Mount Merapi exploded again, this time causing a fireball to rise 2km vertically into the air from the volcano. The magma continued to push its way into the lava dome and ash fell more than 30km away. This all caused raining sand to fall 10km away.

How big was the eruption?

The 2010 eruption was 4 on the volcanic explosivity index (VEI). This is slightly larger than the eruption of Eyjafjallajokull.

What were the impacts of the eruption of Mount Merapi? (social / economic / environmental – primary and secondary effects)

Negative Social Impacts

200,000 people were made homeless by the eruption and 320,000 people were displaced. Emergency shelters had to be moved to 15km away. The danger area was extended to 20km from the mountain and 278,000 people living in the area had to flee their homes. Evacuation centres were overcrowded leading to poor sanitation, no privacy and serious disease risk. Many farmers lost their livelihoods. Lava flows closed many roads and others were closed off for safety reasons. 353 people were killed from the main eruption and the smaller ones that followed. 5000 people were killed due to the earthquake that occurred 50km South-West of Mt Merapi.

Positive Social Impacts

The volcano brings jobs in the form of the tourism industry. Medical use of hot spa water and mud can improve health.

Negative Economic Impacts

Vegetable prices increased because of damage to crops. Planes were grounded in Western Australia because of the risk of damage to aircraft from the ash cloud. Lava flows damaged ski lifts.

Positive Economic Impacts

The eruption brought volcanic tourism although eruptions can cause tourists to cancel visits. Mineral mining increased.

Negative Environmental Impacts

Ash, rock and lava deposited on the sides of the volcano were washed down into towns by rainfall creating a lahar. Sulphur dioxide was blown across Indonesia as far South as Australia. Ash from the volcano eventually led to more fertile soils in the area. Water supplies were contaminated with acidic lava and ash.

Positive Environmental Impacts

A conservation area has been set up around the volcano where it is unsafe to live.
Geothermal energy is a renewable source of energy using steam from hot rocks near the surface. Breathing difficulties from the contaminated air (ash and acidic fumes). Global cooling followed slightly as the ash spread through the upper atmosphere.

What were the responses to the eruption of Mount Merapi?

Short Term

210 evacuation centres were set up either as tents, in schools, churches, stadiums or government offices. 1600 people, either volunteers or military were part of the national aid response. International aid was offered from organisations such as the Red Cross.

Long Term

Formal evacuation centres were eventually set up because building such as schools and government offices were needed for their official uses. 2682 people had to be moved to new safer houses permanently. The government is making money available to farmers to help replace their livestock. The government has set up a special task force to support people that have been affected by the volcano either by family issues, or because they have lost their jobs.

Prediction systems

The monitoring of Mt Merapi began in 1942 using Seismometers. Some of these volcano monitoring stations are still around today. The monitoring systems have been updated as technology and scientific understanding has progressed. During the 1950s and early 1960s many of the stations were deprived of equipment due to a lack of funds, yet by the 1970s considerable improvement occurred with the supply of new equipment. Other measurements on the volcano are magnetic measurements and tilt measurements. Small changes in local magnetic fields have been found to coincide with eruptions and tilt measurements show the inflation of the volcano as magma rises.