Mount Merapi, also known as Gunung Merapi in Indonesian and gunung měrapi in Javanese, is an active stratovolcano located on the border between Central Java province and the Special Region of Yogyakarta, Indonesia. It is the most active volcano in Indonesia and has erupted regularly since 1548. The volcano is about 28 kilometers (17 miles) north of Yogyakarta, a city with a population of 2.4 million. Thousands of people live on the sides of the volcano, with villages as high as 1,700 meters (5,577 feet) above sea level.

Smoke is often seen rising from the mountain’s top, and eruptions have caused deaths in the past. A pyroclastic flow from a large explosion on November 22, 1994, killed 27 people, mostly in the town of Muntilan, which is west of the volcano. A major eruption also happened in 2006, shortly before the Yogyakarta earthquake. Because of the dangers Merapi poses to nearby people, it was named one of the Decade Volcanoes, which are studied closely due to their history of large eruptions and closeness to populated areas.

On the afternoon of October 25, 2010, Merapi erupted on its southern and southeastern slopes. Over the next month, 353 people died, and 350,000 people were forced to leave their homes. Most damage was caused by pyroclastic flows, and heavy rain on November 4 created lahars that caused more harm. By November 30, most of the cracks on the volcano had stopped erupting, and four days later, the official danger level was lowered. The eruptions changed Merapi’s shape, reducing its height by 38 meters (125 feet) to 2,930 meters (9,613 feet).

Since 2010, Merapi has had several smaller eruptions, including two phreatic eruptions on November 18, 2013, and May 11, 2018. The first, which was larger, was caused by rainfall and internal volcanic activity, and smoke rose to a height of 2,000 meters (6,562 feet). There have been several small eruptions since early 2020, which are of great interest to scientists who study volcanoes.

Etymology

The name Merapi comes from two words: "Meru," which is a Sanskrit word meaning "mountain," and "api," a Javanese word meaning "fire." This means that Merapi can be translated as "Mountain of Fire" or "Fire Mountain."

According to Mahdi (2005), the name Merapi is formed by adding the Old Malay prefix "mər-" to the word "api" (fire). This prefix is thought to be the origin of the modern Malay and Indonesian prefix "ber-." Mahdi also suggests that the same pattern appears in the name of another volcano, Mount Marapi in West Sumatra. If "mər-" is indeed the ancestor of "ber-," then the name Merapi would have the same structure as the modern Malay and Indonesian word "berapi," which means "to spew fire." When combined with the word "gunung" (mountain), "berapi" forms the modern term for "volcano" in Malay and Indonesian: "gunung berapi."

History

Merapi is the youngest volcano in a group of volcanoes in southern Java. It is located at a subduction zone, where the Indo-Australian plate moves under the Sunda plate. Merapi is one of at least 129 active volcanoes in Indonesia. Part of the volcano lies in the southeastern section of the Pacific Ring of Fire, a region of fault lines stretching from the Western Hemisphere through Japan and Southeast Asia. Studies show that eruptions in the Merapi area began about 400,000 years ago. From that time until about 10,000 years ago, eruptions were usually effusive, with flowing lava that was basaltic. Since then, eruptions have become more explosive, with viscous andesitic lava often forming lava domes. Dome collapse has frequently caused pyroclastic flows, and larger eruptions, which created eruption columns, have also led to pyroclastic flows through column collapse.

Small eruptions occur about every two to three years, and larger ones occur every 10–15 years. Notable eruptions, which often caused many deaths, happened in 1006, 1786, 1822, 1872, and 1930. Thirteen villages were destroyed in the 1930 eruption, and 1,400 people were killed by pyroclastic flows.

The large eruption in 1006 is said to have covered all of central Java with ash. Some claim that the volcanic destruction led to the collapse of the Hindu Kingdom of Mataram. However, evidence from that time is not enough to confirm this.

In April, increased seismic activity and a bulge in the volcano’s cone indicated that new eruptions were likely. Authorities placed nearby villages on high alert, and residents prepared for possible evacuation. On 19 April, smoke from the crater reached 400 meters (1,300 feet), compared to 75 meters (246 feet) the previous day. On 23 April, after nine surface tremors and about 156 quakes signaled magma movement, around 600 elderly and infant residents on the slopes were evacuated.

By early May, active lava flows began. On 11 May, as lava flow became constant, about 17,000 people were ordered to evacuate the area. On 13 May, Indonesian authorities raised the alert level to the highest, ordering all residents on the mountain to evacuate immediately. Many villagers ignored the warnings and returned to their homes, fearing their livestock and crops might be stolen. Activity decreased by mid-May.

On 27 May, a 6.3 magnitude earthquake struck about 50 kilometers (31 miles) southwest of Merapi, killing at least 5,000 people and leaving over 200,000 homeless in the Yogyakarta region. This increased fears that Merapi might erupt. The earthquake was not a long-period oscillation, a type of seismic activity linked to major volcanic eruptions. On 6 June, about 11,000 more villagers were evacuated as lava and superheated gas clouds flowed down the volcano’s slopes toward Kaliadem, a location southeast of Mount Merapi. Locally, these pyroclastic flows are called "wedhus gembel" (Javanese for "shaggy goat"). Two people died as a result of the eruption.

In late October, the Center for Volcanology and Geological Hazard Mitigation (CVGHM) reported that Merapi’s seismic activity had increased starting in early September. Observers near the volcano reported hearing an avalanche on 12 September. On 13 September, white plumes were seen rising 800 meters (2,600 feet) above the crater. Lava dome inflation, first detected in March, increased from 0.1 mm (0.0039 inches) to 0.3 mm (0.012 inches) per day, reaching 11 mm (0.43 inches) per day by 16 September. On 19 September, earthquakes remained frequent, and the next day, CVGHM raised the alert level to 2 (on a scale of 1–4). Lava from Mount Merapi began flowing down the Gendol River on 23–24 October, signaling a likely eruption.

On 25 October, the Indonesian government raised Merapi’s alert level to 4 (the highest) and warned villagers in threatened areas to move to safer ground. People living within a 10 km (6.2 mi) zone were ordered to evacuate. At least 19,000 people were affected by the evacuation orders, though the number who complied was unclear. Officials reported about 500 volcanic earthquakes on the mountain over the weekend of 23–24 October and noted that magma had risen to about 1 km (3,300 feet) below the surface due to seismic activity.

After multiple eruptions in November 2010 that were more intense and longer than those in 1872, the frequency and intensity of eruptions began to decrease. By this time, 153 people had been reported killed, and 320,000 were displaced. Later, eruptive activity increased again, requiring the continuation of the Level 4 alert and exclusion zones around the volcano. By 18 November, the death toll had risen to 275. It reached 324 by 24 November, and Syamsul Maarif, head of the National Disaster Mitigation Agency (BNPB), explained that the death toll increased after some victims died from severe burns and more bodies were found on the volcano’s slopes.

After more intense eruptions in late November, Yogyakarta’s Disaster Management Agency reported about 500 cases of psychological problems among eruption survivors in Sleman district and about 300 cases in Magelang. By 3 December, the death toll had risen to 353.

On 3 December, Syamsul Maarif, head of the National Disaster Management Agency (BNPB), and Dr. Surono, head of CVGHM, issued a joint press release in Yogyakarta. At 9:00 am, CVGHM lowered Merapi’s alert level to Caution Alert (Level III). They noted that hot ash clouds and incandescent material could still occur. The Geological Agency recommended no community activities in disaster-prone areas and maintained an exclusion zone of 2.5 km (1.6 mi) around the volcano.

A phreatic eruption began on 11 May, prompting the evacuation

Monitoring

Mount Merapi has an active volcano monitoring program. Seismic monitoring started in 1924, and some monitoring stations are still in use today. The Babadan, Selo, and Plawangan stations were updated with new equipment over the years. In the 1950s and early 1960s, some stations did not have enough equipment or money, but after the 1970s, new equipment was added. Some observation posts built before 1930 were destroyed during the 1930 eruption, and newer posts were moved to safer locations. After the 1994 eruption, the Plawangan post and equipment were relocated to Kaliurang to protect volcanological staff. The volcano is monitored by the Deep Earth Carbon Degassing Project.

The 1930 eruption was preceded by a large group of earthquakes. Today, eight seismographs around the volcano help scientists locate the centers of tremors and quakes.

A zone about 1.5 km below the summit has no earthquakes. Scientists believe this area is where magma is stored and feeds eruptions.

Other measurements include magnetic and tilt readings. Small changes in the local magnetic field often happen before eruptions. Tilt measurements show the volcano swells when magma fills the chambers beneath it.

Lahars, which are mudflows made of volcanic material and water, are a major hazard on the mountain. Rain can move pyroclastic flow deposits, causing lahars. Lahars create high-frequency seismic signals. Studies show that when it rains more than 50 mm per hour, lahars are often created.

Check dam

About 90 out of 258 sand barriers (sabo) were damaged. This is 30 percent of the total number. The cost to repair the damaged barriers is approximately Rp 1 trillion, which is about $116 million.

Sterile zone

After the 2010 eruption, three Indonesian government departments created a restricted area where no one can live permanently, and no buildings or structures are allowed in nine villages: Palemsari, Pangukrejo, Kaliadem, Jambu, Kopeng, Petung, Kalitengah Lor, Kalitengah Kidul, and Srunen. These villages are located in Cangkringan district.

National park

In 2004, an area covering 6,410 hectares near Mount Merapi was made into a national park. The Ministry of Forestry's decision to create the park was later challenged in court by The Indonesian Forum for Environment because local people were not consulted about the plan. During the 2006 volcanic eruption, many residents were unwilling to leave their homes because they were afraid their houses might be taken over to expand the national park, leaving them without a place to live.

Museum

The Merapi Museum Center is located at Kaliurang Street, Kilometer 25.7, Pakem subdistrict, Sleman, Yogyakarta. The museum includes a replica of Merapi's eruption that occurred after 2010. Since the most recent eruption, visits by Indonesian students to the museum have increased by 30 percent.

Mythology

Merapi is very important to the Javanese people, especially those living near its crater. Many myths and beliefs are connected to Merapi.

Most villages near Merapi have their own stories about how the mountain was created, but these stories share many similarities. One story says that when the gods first made the Earth, Java was unbalanced because Mount Jamurdipo was located on the western end of the island. To fix this, the gods (often called Batara Guru) decided to move the mountain to the center of Java. However, two armorers, Empu Rama and Empu Permadi, were already making a sacred keris at the site where the mountain was to be moved. The gods warned them to leave, but they ignored the warning. In anger, the gods buried Empu Rama and Empu Permadi under Mount Jamurdipo. Their spirits later became rulers of all mystical beings in the area. To honor them, Mount Jamurdipo was renamed Merapi, which means "fire of Rama and Permadi."

The Javanese believe the Earth is not only home to humans but also to spirits (makhluk halus). Villages near Merapi believe that one of the palaces (kraton) used by the rulers of the spirit kingdom is inside Merapi. This palace is said to be a spiritual version of the Yogyakarta Sultanate, with roads, soldiers, princes, vehicles, and domesticated animals. In addition to the rulers, the palace is believed to be home to the spirits of ancestors who lived righteously. These spirits are said to serve as royal servants (abdi dalem) and sometimes visit their descendants in dreams to give warnings or prophecies.

To keep the volcano calm and honor the mountain’s spirits, the Javanese offer gifts on the anniversary of the Yogyakarta Sultan’s coronation. For the Yogyakarta Sultanate, Merapi has a significant meaning in their culture because it forms a sacred north-south line between Merapi’s peak and the Indian Ocean, which locals call the Southern Ocean. This sacred line begins at Merapi’s peak, passes through the Tugu Yogyakarta monument near Yogyakarta’s train station, continues along Malioboro Street to the Northern Alun-alun (square) near the sultan’s palace (Keraton Yogyakarta), then to the Southern Alun-alun, and finally reaches Bantul, Samas, and Parangkusumo Beach, where the Opak River meets the Indian Ocean. This line connects the hyangs (spirits of the mountain, often called "Mbah Petruk" by Javanese people), the Sultan of Yogyakarta (leader of the Javanese kingdom), and Nyi Roro Kidul, the queen of the Southern Ocean and a mythical partner of Javanese kings.