Volcanic eruption of Mount Merapi in Indonesia
In late October 2010, Mount Merapi in border of Central Java and Special Region of Yogyakarta, Indonesia began an increasingly violent series of eruptions that continued into November. Seismic activity around the volcano increased from mid-September onwards, culminating in repeated outbursts of lava and volcanic ash. Large eruption columns formed, causing numerous pyroclastic flows down the heavily populated slopes of the volcano. The 2010 eruption of Merapi was the volcano's largest since 1872.
Over 350,000 people were evacuated from the affected area. Many others remained behind or returned to their homes while the eruptions were continuing. 353 people were killed during the eruptions, many as a result of pyroclastic flows. The ash plumes from the volcano also caused major disruptions to aviation across Java.
The mountain continued to erupt until 30 November 2010. On 3 December 2010 the official alert status was reduced to level 3, from level 4, as the eruptive activity had subsided.
Volcanic eruptions.
Recent background.
In late October 2010 the Volcanological Survey of Indonesia (PVMBG) reported that a pattern of increasing seismicity from Merapi had begun to emerge in early September. Observers at Babadan west and Kaliurang south of the mountain reported hearing an avalanche on 12 September 2010. On 14 September 2010 white plumes were observed rising above the crater. Lava dome inflation, detected since March, increased from background levels of per day to a rate of per day on 16 September. On 19 September 2010 earthquakes continued to be numerous, 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 signalling the likelihood of an imminent eruption.
On 25 October 2010 the Indonesian government raised the alert for Mount Merapi to its highest level (4) and warned villagers in threatened areas to move to safer ground. People living within a zone were told to evacuate. The evacuation orders affected at least 19,000 people however the number that complied at the time remained unclear to authorities. Officials said about 500 volcanic earthquakes had been recorded on the mountain over the weekend of 23–24 October, and that the magma had risen to about a below the surface due to the seismic activity.
Chronology of eruptive events.
Monday, 25 October.
Merapi erupted three times on Monday afternoon spewing lava down its southern and south-eastern slopes. Three major eruptions were recorded at 14:04, 14:24 and 15:15 local time. On this day, 222 volcanic seismic events and 454 avalanche seismic events were recorded by Center for Volcanology and Geological Hazard Mitigation monitoring staff at Merapi.
Tuesday, 26 October.
The eruptions on Tuesday started at 17:02. By 18:54 pyroclastic activity had begun to subside following 12 eruption-associated events being recorded by CVGHM monitors. 232 volcanic seismic events, 269 avalanche seismic events, four lava flow seismic events and six pyroclastic flows were recorded in the 24 hours of 26 October. The eruptive events were classified as "explosive events" with volcanic bursts of ejected material, visible flame and pyroclastic hot air flows. A column of smoke rose from the top to a vertical distance of from the summit of Mount Merapi. The first fatalities occurred on this day.
Friday, 29 October.
On Friday eruptive activity included lava ejection with hot ash clouds reported to be flowing down the slopes of the mountain and lasting four to nine minutes. Ash falls reached as far as the Central Java town of Magelang. Scientists monitoring the volcano including Surono, chief of the Volcanology and Geological Disaster Mitigation Center (PVMBG), expressed optimism that the volcanic activity should decrease following the release of lava. Safari Dwiyono, a scientist monitoring Mt. Merapi for 15 years, said the volcanic activity appeared to be easing pressure behind a lava dome that had formed in the crater. The International Red Cross reported that on 29 October, from 07:23 to 21:40, pyroclastic flow from Merapi struck Lamat River, Senowo River, and Krasak River.
Saturday, 30 October.
By early on the morning of Saturday 30 October the volcano was erupting again. Sri Sumarti, head of the Merapi section at the Volcano Investigation and Technology Development Institution (BPPTK), reported the eruptions were louder and stronger than those of 26 October. Ash from the eruptions on 30 October fell more than away and now included ash falls upon the city of Yogyakarta. Soldiers and police posted nearest the volcano were seen fleeing along with hundreds of residents who quickly clogged roads with cars and motorcycles. Black soot fell across a vast area. The morning eruptions lasted for 22 minutes while pyroclastic flows flowed into the Krasak and Boyong River valleys and ash rose into the air, drifting westward toward Magelang. Yogyakarta's Adisucipto Airport was closed temporarily between 05:00 to 07:00. Later that day, Subandrio, head of the BPPTK suggested there would be further eruptions as magma continued to push its way up into the volcano's lava dome. A pyroclastic river flowed from Merapi again on 30 October 2010 at 00:35. A pyroclastic flow headed toward Gendol River, Kuning River, Krasak River, and Boyong River. This was then followed by an explosion from Merapi resulting in a two-kilometre vertical high fire ball rising from the top of the mountain. This eruption caused raining sand to fall on areas to a radius of up to from the volcano. Amongst activities from government and NGO's the Indonesian Red Cross and Red Crescent (PMI) had by this time fielded up to 398 volunteers from branches in the provinces of Central Java, and Yogyakarta. These volunteers assisted in disseminating information to communities to warn of Merapi's level IV volcanic activity. PMI also provided meals for 1,000 displaced people in the Dompol camp. One of these PMI volunteers, Tutur Priyanto, had died on the slopes on 26 October.
Monday, 1 November.
The Center for Volcanology and Geological Hazard Mitigation observation outposts at Mount Merapi began observing at 00:00 and concluded at 06:00 and reported no significant visible activity. Merapi spewed hot clouds in the afternoon. Sulfatara smoke was visible from several posts and avalanches were observed. Mount Merapi erupted at 10:10 local time Monday morning spewing hot clouds and dark fog masses in easterly direction punctuated by loud explosions. Lt Col Soekoso Wahyudi, chief of the Boyolali district military command, was reported by Antara news as saying the explosions this time were louder than those of Sunday evening 31 October. The hot clouds descended on part of the mountain slopes and moved in easterly direction. Local military and police commands deployed personnel on roads in areas around the mountain to regulate traffic which had become clogged by vehicles and people rushing to leave the danger zones. Reports from Klaten, Sleman and Boyolali districts suggested the volcanic explosions were so loud they caused panic and a rush to seek refuge. Merapi's heat and hot ash clouds continued to erupt throughout the day. A thick eruptive ash cloud was reported to rise into the air. The Darwin VAAC reported that a possible eruption on 1 November produced an ash plume that rose to an altitude of a.s.l., according to ground-based reports, analyses of satellite imagery, and web camera views. The WHO reported that Mount Merapi spewed out hot clouds of gas and ash again on Monday morning, 1 November 2010 at around 10:05 local time. Clouds of hot ash and gas billowed up to into the atmosphere, before cascading back down up to around the slopes of Merapi. An uninterrupted stream of smoke clouds were sent into the air for 40 minutes, heading southward toward a nearby river in Sleman regency, and took with it an estimated 2 million cubic metres of rock and earth from the peak. From the previous eruption, Crisis Center MOH reported 42 people died and 103 people were admitted to several health facilities with respiratory difficulties and burn injuries. Up to 70,143 people were reported to have been displaced. Health problems amongst the evacuees included acute respiratory infection, eye irritation, cephalgia, and hypertension. Land transportation beyond the restricted area was not disrupted. Air transportation was affected for flights from and to Yogyakarta and Solo.
Tuesday, 2 November.
On 2 November several airlines including Garuda, AirAsia and SilkAir with international flights to both Yogyakarta and Solo were either suspended or re-routed due to the eruptive activity. CVGHM reported 26 pyroclastic flows on 2 November.
Wednesday, 3 November.
 On 3 November pyroclastic flows travelled up to away from the summit, forcing the government to evacuate people from within the refugee camps set up earlier to accommodate those already dislocated by the volcano. A mid-day report from CVGHM on 3 November stated that 38 pyroclastic flows occurred during the first 12 hours of the day. An observer from the Kaliurang post saw 19 of those 38 flows travel south. Plumes from the pyroclastic flows rose , although dense fog made visual observations difficult. Ashfall was noted in some nearby areas.
Eruptions in the afternoon followed a morning eruption that sent hot gas clouds down the volcano's slopes. The volcano spewed clouds of ash and gas into the sky for more than an hour. Wednesday's eruptions were reported to be the largest since the eruptions commenced. Surono announced that he was moving the shelters further from the summit. Speaking on Indonesia's Metro TV network he said, "this is the first time that the eruption has continued for more than an hour, so I decided to move the shelters to away from the summit". The shelters had previously been set up away. Surono added that the energy from the eruption on 3 November was three times greater than that of the first eruption in the previous week. Bambang Ervan, a spokesman from the Transportation Ministry, said an official warning had been issued to all airlines to "use alternative routes for safety reasons due to the volcanic ash."
Thursday, 4 November.
Heavy rain during the night of 3–4 November triggered lahars with mixtures of water and rock debris cascading down the Kuning, Gendol, Woro, Boyong, Krasak and Opak Rivers on the slopes of the volcano. A bridge was destroyed and riverbanks damaged. The eruption at 05:55 was reported as being five times stronger than the initial eruption on 26 October 2010. On 4 November Merapi had been erupting for 24 hours without stopping. Pyroclastic flows of spread as far as from the crater reaching toward the edge of the then exclusion zone, and lava flowed into the mountain's rivers. Herry Bakti Gumay, Director General of air transportation, stated on 4 November that the warning released to all airlines operating flights into Yogyakarta would not be withdrawn until conditions returned to normal.
Friday, 5 November.
Merapi erupted strongly early Friday morning. Volcanic ash fell at Cangkringan district and its surroundings from the crater. Due to continuous large eruptions, the BNPB extended the safety zone to a radius of and Yogyakarta's airport was closed again for 3 hours in the morning. Residents who were within of the summit were asked to leave and seek a safer place.
Volcanologists reported the eruptions on Friday 5 November to be the biggest since the 1870s and officials announced by loudspeaker that the mountain's danger zone had been expanded to from the crater. Bronggang, a village from the crater saw its streets blanketed by ash up to deep. By this point, more than 100,000 people had been evacuated and the scientists monitoring the events were withdrawn from their posts to a safer distance. The Australian Bureau of Meteorology, Volcanic Ash Advisory Center (VAAC) issued an ongoing code red Aviation Volcanic Ash Advisory and reported MTSAT-2 satellite image-derived information indicating a volcanic ash plume to ( – FL550), extending to the west and southwest of the mountain.
Saturday, 6 November.
The Center for Volcanology and Geological Hazard Mitigation observation outposts reported high intensity ash falls on the slopes of Mt Merapi. At 23:51 a flash of smoke, hot air winds and flames as high as occurred to the west, north and to the east. The day's volcanic activity was very high, with sequential hot ash clouds erupting from the mountain. The alert level for the remained at level 4 and the official exclusion zone was a radius from the summit of Mount Merapi.
Sunday, 7 November.
On Sunday, 7 November President of Indonesia Susilo Bambang Yudhoyono opened a limited cabinet meeting at Gedung Agung, the presidential residence in Yogyakarta located 30 kilometres south of the