Where is krakatoa found

This is your chance to get to know one of the most famous volcanoes with an expert and witness the dramatic changes from the Dec collapse.

During this physically easy expedition, you have the unique opportunity to experience one of the world's most beautiful and powerful volcanoes. The exact itinerary varies from tour date to tour date, but we usually spend between 2 and 4 full days and nights on and around the volcanic islands of Krakatau. Depending on the intensity of Anak Krakatau's activity we either camp on the beach of the active volcano itself or make our camp on one of the surrounding islands.

Watching Krakatau's fireworks when it is active is truly spectacular and we will do so from various viewpoints both on Anak Krakatau itself and the neighboring islands, using the chartered boat we have at our disposal. Even when there is no eruption, the active volcano of Anak Krakatau with its lunar landscapes, fumaroles and frozen lava flows , and the surrounding islands' spectacular pumice cliffs on what remains of the island complex destroyed in , is well worth exploring.

Your expedition leader and tour guide Andi has been closely watching this volcano's activity and changes over the past 15 years and will happily share his geological knowledge with you! Hot springs and beautiful coral reefs and other natural highlights of this unique bioreserve make this a perfect trip if you like a volcano extension out from Jakarta. The tasty camping food with fresh fish and overall excellent organization by our experienced local crew round up this trip into an unforgettable travel adventure.

First visit to our site? Try our free app! Android iOS version. Volcano Calendar Volcano Calendar We're proud to present our volcano calendar: 13 different and attractive images of volcanoes, volcanic landscapes and phenomena taken during volcano tours over the past two years. Volcano Videos. Visit our video channel on youtube!

Sea-Floor spreading. Divergent plate boundaries in oceans Two ocean plates move apart from each other. Hot upwelling mantle material forms magmas that continuously produce new oceanic crust. An ocean widens. Photos from Kamchatka Kamchatka in Russia's far east is one of world's remotest regions and has an almost unparalleled density of active volcanoes.

The explosion was recorded by an infrasonic microphone sensor installed at the Pasuaran post observatory. John Seach visited on 12 August and found that the volcano was not erupting then, but was steaming vigorously on the N side of the summit crater. Pulses of steam every minute reached 20 m above the summit. Lava bombs, 0. The bombs left 1. The fresh impact craters were caused by both lithic and lava bombs.

Observers on a boat 1. The top m of the active cone was steaming from multiple locations. On the NW side, 60 m below the summit, a fumarole emitted blue gas. During September the number of explosion and volcanic earthquakes increased, but the number of small explosion earthquakes sharply decreased September.

Seismic activity increases during mid-August ; Alert Level remains at 2. A thick white plume reached 25 m above the summit several times during October through December During 27 August through 16 September at Krakatau, available seismic data were dominated by explosions and shallow volcanic earthquakes table 1. The seismograph broke on 16 September but was repaired by 26 August , when it showed a slight increase over the previous interval when data were available.

No surface activity accompanied the increased seismicity. Volcanic events decreased during early September. The volcano remained at Alert Level 2 through at least 8 September. Table 1. Earthquakes registered at Krakatau during 27 August through 8 September The seismic system was down during 16 September August Courtesy of VSI.

Seismicity dominated by volcanic earthquakes through at least December During 9 September through at least late December , seismicity at Krakatau was dominated by A-and B-type volcanic earthquakes table 2. Throughout the report period, clouds obscured the view of the summit. Krakatau remained at Alert Level 2.

Table 2. Earthquakes registered at Krakatau during 9 September December No data were available during September.

Courtesy VSI. Volcanic earthquakes continue; thermal alerts during July-September Seismicity at Krakatau was dominated by volcanic and tectonic earthquakes during 30 December March table 3. The hazard status remained unchanged at Alert Level 2.

Table 3. Seismicity at Krakatau during 30 December March The first alert occurred on 31 July when one alert pixel was detected with an alert ratio of The anomalies increased during August and on 9 August the anomaly consisted of two alert-pixels with a maximum alert ratio of Other major anomalies occurred on 1 September four alert-pixels with maximum alert ratio of These anomalies correspond to an increase of activity at Krakatau characterized by ash and bomb emission during August and an increase in the number of explosion and volcanic earthquakes during the first half of September , reported by the Volcanological Survey of Indonesia BGVN and The coordinates of the centers of the alert pixels are tightly grouped around the summit of the main cone.

Bearing in mind that each pixel represents radiance from an area of ground more than 1 km across, the alert pixels could represent radiance from the active vent or from hot ejecta close to the vent.

According to reports from the Volcanological Survey of Indonesia VSI , no visual observations were made this month due to foggy weather. The volcano remained at alert level 2 for the month. They also noted that relatively few volcanic and tectonic earthquakes were recorded during the weeks of and June Specifically, the June record consisted of 9 deep volcanic earthquakes, 19 shallow volcanic earthquakes, and 5 tectonic earthquakes; the record of June consisted of 6 deep volcanic earthquakes, 17 shallow volcanic earthquakes, and 4 tectonic earthquakes.

In the week of June, a significant increase in shallow volcanic earthquakes was observed, although no tectonic earthquakes were recorded. The sesimic record for that week showed 11 deep volcanic earthquakes and 63 shallow volcanic earthquakes.

Both volcanic and tectonic earthquakes were recorded for the week of June, with 7 deep volcanic earthquakes, 61 shallow volcanic earthquakes, and 2 tectonic earthquakes detected. Due to continued foggy weather, no visual observations could be made at Krakatau during July and through 17 August. Throughout this period the volcano remained at Alert Level 2.

Seismicity reported by the Volcanological Survey of Indonesia VSI between 30 June and 17 August consisted mostly of shallow volcanic events table 4 , although 36 deep volcanic earthquakes were recorded during the week of 30 June-6 July.

Table 4. Seismicity at Krakatau, 30 June August A report of activity at Krakatau for the period August was provided by the Volcanological Survey of Indonesia. There was increase in volcanic earthquakes during this time, while tectonic earthquakes decreased. No visual observations were made due to foggy weather. Seismicity consisted of 12 deep volcanic earthquakes, 56 shallow volcanic earthquakes, and three tectonic events.

The hazard status was at Alert Level 2 on a scale of Intense activity occurred at Anak Krakatau beginning on 4 July , when gas and steam emissions increased. Based on the increased activity, the hazard status was upgraded to Alert Level II yellow on 16 July; visitors were not allowed to approach the summit or crater. Seismicity recorded at the Kalianda station after 18 July through 15 August was variable, but did not exhibit the high numbers recorded in the first half of July.

Table 5. Seismicity at Krakatau, 4 July August Minor eruptions beginning October ; seismic data for Eruptive activity in recent years was low at Krakatau. Seismic data collected during this period figures 15 and 17 , although intermittent and variable, suggests mainly low-level activity discussed in more detail below.

Starting on 23 October reports noted multiple gray plumes from eruptions lasting minutes; these vented from a crater near the summit of Anak Krakatau figure Similar eruptions were continuing in early November figure Activity during April September On 13 April increased seismicity prompted authorities to raise the Alert Level to 2 on a scale of Seismic activity decreased over the next four days to a normal level.

Visitors were banned from the summit and crater of Anak Krakatau due to toxic gas emission. Another increase in seismic activity was reported around 16 May. Elevated seismicity was also recorded on 24 September , 8 December , and June figure On figure 15, a conspicuous, longer period of high seismicity occurred during most of December , when tremor and low-frequency events also increased.

That peak on figure 15 ended prior to the end of the month. No eruptions were noted in available reports by CVGHM for these episodes of elevated seismicity in or For the intervals where data were available during the first eight months of , seismicity was generally moderate to low.

All data are acquired continuously and are transmitted to the Pasauran Observatory western Java via digital radio telemetry. In Pasauran, the data are collected and transmitted to a server in Jakarta. Three stations are located on Anak Krakatau figure A fourth station on Sertung island consists of a short-period seismometer and a digital camera with a view of Anak Krakatau.

During October , minor eruptions occurred at Anak Krakatau BGVN , an island and active vent on the rim of the famous larger caldera whose name often is misspelled as "Krakatoa.

Villagers and tourists were advised not go within 3 km of the summit. According to an Associated Press news article, "red-hot lava flares" from Anak Krakatau rose m above the S crater on 6 November. Officials said, that on that day there were eruptions coupled with 11 volcanic earthquakes, 54 shallow volcanic shocks, eight deep volcanic tremors and 44 shallower tremors. The volcano spewed "smoke" 29 times.

As reported by VolcanoDiscovery 's Tom Pfeiffer, who visited there from November, emissions were relatively constant. He noted that all activity occurred from the newly formed crater on the upper S flank just below the old summit crater figure On 21 November, the new crater had an oval shape, approximately 50 x 70 m.

Dense, dark brown, billowing ash clouds escaped in pulses from the crater at near-constant intervals of about 2 minutes, rising typically m above the crater and drifting E. A few blocks were ejected along with the ash clouds figure Pfeiffer also reported that at more irregular intervals, about min apart, more violent, small vulcanian explosions interrupted the weaker ash venting events.

The more violent explosions consisted of a sudden spray of mostly solid rocks and few incandescent scoria, followed by more powerful and turbulent ash plumes that rose up to 1 km above the crater figure Generally, these vulcanian explosions occurred after a slightly longer quiet period and, in most cases, the length of the quiet period correlated with the force of the explosion.

Pfeiffer noted that several more powerful explosions occurred at intervals of approximately hours. The strongest, on November, showered the whole island with incandescent blocks, ignited bush fires, and produced a very loud cannon-shot noise that rattled windows on the W coast of Java, 40 km away figure Other, unusually large blasts occurred at around on 21 November and at around and on 23 November figure Early on 23 November, activity became more ash-rich and the vigor of the individual events increased slightly over the next two days.

The pace of single explosions stayed at near-constant intervals of about 2 minutes. During November, ash plumes typically rose to over 1 km above the crater and were easily visible from the W coast of Java.

The thermal alerts occurred on twelve occasions between 27 October and 9 December Seven of these took place between 16 and 26 November Variable eruptive activity from late to mid; plumes to 3 km altitude.

This small but growing post-caldera cone first gained attention with a eruption Simkin and Fiske, The detailed chronology of behavior during October to 3 July is sometimes sketchy, but activity was apparently quite variable.

Although one or more lulls may have occurred, eruptions clearly continued into The Alert Level was lowered and raised again throughout and into as activity warranted. People were advised not to go within 1. Activity through August According to a news article, by 22 November , seismicity had declined in frequency. Based on an Antara News article, this decline in seismic activity was interrupted by incandescent rock ejections on 20 January accompanied by plumes that rose to altitudes of 2.

Seismicity again declined in early February , and eruption plumes and ejected incandescent material were not seen during 4 February to mid-April Seismicity increased during April , with the number of events per day peaking on 20 April. Ash plumes accompanied by ejected incandescent rocks were noted during CVGHM field observations on 16, 17, and 18 April.

During 22 June-1 July , the number of seismic events decreased significantly and booming noises were less frequently heard. On July ash emissions declined, although on 1 and 2 July low level ash plumes rose to an altitude less than 3 km and drifted NW. According to an article in Antara News, eruptions increased in frequency during August On 12 August, monitoring personnel reported that active lava flows and dense emissions of "smoke" continued, but that the frequency of earthquakes and eruptions had declined.

Monitoring personnel during that period observed plumes, active lava flows, and rock ejections. Activity during March-May Seismicity increased significantly during March and remained high through 5 May. During periods of clear weather on 25 March, white-to-gray plumes rose m above the volcano. During March and 1 April clear weather revealed ash plumes rising m. On 2 April an ash eruption was seen on satellite imagery and reported by a pilot.

During March through 25 April , an episode of heightened seismicity produced thousands of eruptive signals table 6 ; however, the seismic station shut down overnight during April, and completely shut down during April.

CVGHM believed that this shutdown was the result of either blockage of sunlight from reaching the solar panels by tephra collecting there or because of impact-induced damage to the panels. Table 6. Type and number of earthquakes and tremor recorded at Krakatau during 27 March-6 May Values shown are daily averages except the following: 1 and April: during hour period daylight ; 2 30 April: starting at local time from a new, safer location; 3 06 May: during to local time.

No data was recorded during April. During April observers reported grayish-white to black plumes that rose to , m above the crater. They heard many loud booms. Some of the lofted ash blew E to SE and caused fallout up to 5 km away. According to a news article on 29 April , some residents in southern Sumatra near Krakatau evacuated because they had observed increased volcanism during the previous week.

For example, observers reported loud blasts, lava flows, and ash plumes. In clear weather on 5 May "smoke" rose m above the crater. An Antara News article published on 18 June indicated that in the previous several days the number of small eruptions increased tremendously.

It said that, according to Anto Prambudi, head of the monitoring post in Pasauran village, at least small eruptions were recorded during June In later , comparatively few alerts occurred, but became more prevalent again during mid-January After that, they were few or absent until mid-April; alerts were common and strong during the week ending 4 May.

Consistent alerts were the pattern until the week ending 7 June, which had no alerts, but some continued in the next few weeks.

After that, alerts again became common again, particularly abundant during April an episode of eruptions and heightened seismicity and continued regularly through at least 3 July The gap in alerts may have been influenced by downward biasing from poor weather conditions. On the other hand, for the cases with high numbers of alerts, false positives due to fires for example were unlikely on the desolate landscape of Anak Krakatau. Simkin, T.

On 25 March activity increased significantly, with the recording of 19 eruptions. Eruptive activity then continued without pause until 6 May when the hazard status was elevated to Alert Level 3 Siaga. The VAAC did not detected the plume on satellite imagery. Visual observations of the summit were often obstructed by fog, although a gray cloud rising as high as 1, m above the summit was observed at a clear moment on one undisclosed day in August.

Booming eruptive sounds were recorded 49 times in August and once in September. Table 7. Seismically detected signals at Krakatau, including tremor and earthquake, registered by the Pasauran observation post during August through 29 October Instrument locations were discussed in BGVN although the status of these stations was not discussed.

Where reported the table also presents ranges of amplitudes in millimeters, mm , duration in seconds, s , and S-wave minus P-wave arrival times S-P. CVGHM also reported two major seismic events over the reporting period at distance from Krakatau with little discernable impact there. On 16 October , a tectonic earthquake originating from Ujung Kulon-Jawa Barat, located at the W tip of Java, occurred with a magnitude of 6. CVGHM stated that the volcanic seismic signals at Krakatau following the earthquakes on 16 August and 16 October do not indicate an increase in volcanism.

Anak Krakatau the active post-collapse cone of the infamous Krakatau volcano, figure 23 began another eruptive phase around 25 October , characterized by up to hundreds of explosions per day e.

In November , Arnold Binas documented explosive activity, ballistic bombs, column collapse generating pyroclastic flows, and volcanic lightning in some spectacular photographs figure Ash fall in early January covered the solar panels running seismometers monitoring Anak Krakatau, rendering them inoperative until rainfall cleared the ash from the solar panels.

In March , the activity at Anak Krakatau decreased and the eruption was considered to be over. According to a local news service TO:DAY , the head of the Anak Krakatau monitoring post reported that in the previous month, volcanic earthquakes became fewer and at greater focal depths. They had ranged from a high of shallow earthquakes per day, declining to dozens per day in March In August, Andi Rosadi reported on the Volcano Discovery website that the seismometer monitoring Anak Krakatau was again damaged by explosions venting from the summit crater, noting "many quite big new bombs around the old crater.

Rosadi also described and photographed large areas of incandescence within the summit crater on 8 August , reporting a lava dome or "dry lava lake glowing in the central crater" figure On 30 September, CVGHM reported that the seismometers were again operational following 18 September, and increased the Alert Level from 2 to 3 on a scale from 1 to 4 , citing visual and seismic observations.

Visually, while no ash producing eruptions had occurred from September, CVGHM reported that the E flank of the volcano was covered in solfataras, with thin gusts of smoke within the crater and along crater walls. They also reported vibration in the body of the volcano within distances of m from the summit. Seismically, from September, CVGHM reported persistent volcanic earthquakes volcanic earthquake swarms , noting that volcanic earthquakes had reached a level of events per minute.

As of 3 October, the Alert Level remained at 3, and residents and tourists were prohibited within 2 km of the crater. Plumbing of the Krakatau system. Three recent publications addressed magma generation and plumbing of the Krakatau system from different disciplinary approaches.

Employing mineral-melt equilibria thermo-barometry on Krakatau's phenocryst phases of clinopyroxene and plagioclase, Dahren and others demonstrated that clinopyroxene crystallizes at km depth, while plagioclase crystallizes at km depth. The two crystallization depth ranges could suggest multiple magma storage regions in the Krakatau system. From seismic tomography and inversion, Jaxybulatov and others reported a multi-layered structure beneath the Krakatau system figure They found their model similar to the one noted above Dahren and others, They also reported that the deep-focus earthquakes they studied km focal depths were likely related to phase transitions and fluid fluxes in the subducting slab.

They suggested these could lead to diapirism and formation of magma chambers in the overlying mantle wedge and crust. This result is not dissimilar to that of Dahren and others , but? They further noted an aseismic gap in the Wadati-Benioff zone of the subducting plate at km depth.

They inferred that this gap is likely the consequence of partial melting "inhibiting stress concentration necessary to generate stronger earthquakes," while an increased occurrence of earthquakes in the lithospheric wedge above probably reflects magma ascent.

Revised first millenium eruption date. Prior to , a caldera-forming event at Krakatau "Proto-Krakatau" was hypothesized to have occurred circa CE. From an intensive, multi-disciplinary approach, Wohletz hypothesized that the catastrophic event actually occurred in the year prior to widespread climate perturbation during CE. He noted that the th century of the Shaka calendar was probably previously mis-aligned to CE of the western calendar.

Since Wohletz , the date of this eruption is widely accepted as CE see inset of figure 23 for map representation of the caldera's topographic margin. Dahren, B. Jaxybulatov, K. Wohletz K. Union, v. Many earthquakes and some mild eruptions during October-November Our previous report BGVN discussed two eruption episodes: one from 25 October to March , and another from August to about 1 October During the last two weeks of September , the volcano produced persistent volcanic earthquake swarms and thin emissions BGVN This report discusses two visits to the volcano in During November a photographer noted steady degassing, then observed the start of a hour interval of minor but repeated Stombolian eruptions see next section.

His website contains photos of the volcano. Youtube features a video he took on the same subject. His visit to Anak Krakatau during November took place during an interval of gas emissions devoid of ash. He stayed up all night to observe Anak Krakatau emit a steady, white, ash-free plume.

At dusk on 12 November he noticed that the crater glowed bright red and after a few hours a series of mild Strombolian eruptions occurred in a sequence that lasted 12 hours figure The time between the eruptions was from 30 seconds to a few minutes.

Some of Andersen's photos captured glowing pyroclasts arcing tens of meters above the crater rim figure 29b, c. Anderson saw ash lava bombs in the plume during these eruptions.

He noted that the lava bombs ejected over the crater mainly fell back into the crater. During the night the crater remained almost constantly illuminated by the glowing bombs and the fragments they created when they landed. The eruptions were often accompanied by loud sounds from the volcano. See earlier Bulletin reports for maps of the Krakatau complex and of the post-collapse cone that formed an island and now continues as the active vent Anak Krakatau, Daughter of Krakatau; for example, figure 23 in BGVN The complex is famous for the devastating caldera-forming eruption in Simkin and Fiske, That eruption injected millions of tons of fine ash, aerosols, and sulfate particles into the atmosphere.

That eruption and associated tsunami claimed over 36, lives and awakened the world to caldera collapse Self and Rampino, Lockwood and Hazlett noted that the eruption "impressed European observers with remarkable, smog-like sunsets and silvery midday skies. This inspired a number of paintings, possibly including the lurid sky in Edvard Munch's famous work The Scream, which he painted in During that period, the volcano's non-eruptive periods lasted between 1 and 6 years.

During the past few years, Anak Krakatau underwent several eruptive phases, followed by relatively quiet phases BGVN , , and Lockwood, J. Self, S.

One of our previous reports on Krakatau BGVN discussed two eruption episodes, one spanning from 25 October to March and another beginning in August and continuing through the end of that report, around 1 October During the last two weeks of September volcanic earthquake swarms and diffuse emissions persisted. This report summarizes behavior chiefly during 1 October through early October The Alert Level was lowered after that and remained low into at least mid-January The smaller feature Anak Krakatau grew to form an island well after the eruption and continues as the active center.

October The Alert Level was raised to 3 on a scale of on 30 September , prohibiting visitors and residents from approaching within 2 km of the active crater. On 8 October , a Jakarta Post article stated that activity at Krakatau was increasing; the number of seismic events on 6 October was 5,; on 7 October, 5,; and on 8 October, 5, The lowered Alert Level excluded visitors and residents from approaching within 1 km of the active crater.

When views were clear during June, observers saw occasional diffuse white plumes above the crater. In June, July, and August, the respective seismic events totaled 1,, , and 2, Detailed seismicity during 1 June-2 September is cataloged in table 8. Table 8. Type and occurrence of earthquakes and tremor at Krakatau during 1 June-2 September ; '-' indicates data not reported.

Seismicity increased on 2 September CVGHM recorded continuous tremor, and a Strombolian eruption ejected lava m above the crater. At times, residents heard booming sounds that rattled windows. Ashfall on 2 September prompted officials to recommend that residents and tourists wear masks outside and not venture within 3 km of the volcano. The Jakarta Post indicated that government officials planned to distribute , masks to residents in a number of affected districts in anticipation of further Krakatau explosions.

According to Antara News , less intense tremor continued on 4 September. September eruption and visit by Volcano Discovery.

A Volcano Discovery group toured Krakatau during the first several days of September and observed what they noted was the largest explosion there in ten years. They noted that seismic activity recorded by CVGHM peaked on 2 September, with a day of continuous explosions and lava descending the volcano's E and W flanks.

Photos showed lava entering the sea figure The Volcano Discovery group noted that the eruption had altered part of the S and W crater rim, splitting the rim into two parts. They saw an abundance of lava bombs on the volcano's flanks in the forest, indicating the force of the explosions. The group indicated that by 5 September, activity had greatly diminished and incandescence from the crater was absent. On 6 September, Krakatau was calm with limited seismic activity reported by the observatory.

On 8 September, the Jakarta Post also reported that seismic activity had greatly diminished during the previous two days. However, this news account noted that residents in Bandar Lampung still reported ashfall.

The article also stated that ash from the eruption had damaged volcano-monitoring equipment. The following describes his observations during On 8 January , during a 3-hour visit, Andersen observed no Strombolian activity, in contrast with his observation on 13 November On his next visit, during February, he reported medium to heavy venting from the crater and fumarolic activity that was more intense than the activity during January.

He noted continuous steam-and-gas emissions that rose m and incandescence at night, but no eruptions. During a visit on April , Andersen noticed that the S part of the crater was illuminated at night. He further reported that on 7 April, Krakatau started to produce small eruptions from the S part of the crater, the same side as the growing lava dome.

During May, Andersen noted that activity at Krakatau had decreased somewhat in the previous several weeks. Steam plumes reached a height of m and seemed less intense than during his visit in April. He noted incandescence at night, but it was less intense that the previous month. Andersen reported on 7 April: "footage taken by Pierre Fortine showed no sign of any lava dome, but the red glow that is often clearly visible at night from Verlaten, Lang, or Rakata are in fact multiple glowing vents some of them were gas vents that were burning and red hot material surrounding them.

The lava dome that people have claimed to observe [through] February to April may have been destroyed during the last small eruptions that I reported of in April. Shallow earthquake data recorded by the Krakatau Volcano Observatory in Pasauran PVMG shows that the level of activity remains on the relative same level as last month.

During June, he reported that activity had decreased since April and May. He stated that incandescence was almost non-observable, and steam plumes only rose m on this visit compared to m in May , and were at times non-existent.

On 3 September , Andersen wrote that he had heard continuous booming noises half way from Java, and that large booming sounds could be heard in the villages of Carita and Anyar or Anyer , neighboring villages on the W coast of Java, about 50 km ESE of the volcano.

As he approached the volcano, he noted a high plume from the main vent and the ejection of lava bombs to heights of up to m. An area on the SE shore also emitted a large steam plume. I first thought this was the result of new geothermal activity, but first realized later that this was in fact a new lava flow.

On a visit during October , Andersen observed no activity other than a weak and irregular steam plume and, at night, "some small spots of glowing lava, near and on the lava flow on the western flank. He reported that the lava had flowed down both the W and E sides of the volcano, leaving deep scars on both flanks. According to Andersen, news accounts had reported the lava flow on the E flank, but few had noted the one on the W flank, which was significant, although not as great as the one on the E flank.

Diffuse white plumes to m; shallow and deep volcanic earthquakes in Volcanic earthquakes and seismicity related to fumarolic emissions has been reported between January and July , but the only eruption during that time was an ash plume seen by a pilot on 31 March Seismicity, which was high through at least 11 August, continued to be dominated by shallow and deep volcanic earthquakes, as well as signals indicating emissions figure Eruption during February sends large lava flow down the SE flank.

The seismograph at the Anak Krakatau Volcano Observatory detected an eruption at local time UTC , but the eruption was not observed visually because of cloudy weather.

There had been a swarm of volcanic earthquakes about one day earlier, and seismicity had significantly increased 3 hours before the eruption.

After the eruption, seismicity gradually decreased. Although thermal anomalies were frequently recorded in figure 36, bottom , they may have been a result of strong hot fumaroles at the summit dome; no PVMBG or tourist reports indicated active lava flows or ash plumes.

Emission earthquakes increased beginning on 17 February and gradually formed continuous tremor. Satellite thermal anomalies identified by the MIROVA system showed a strong sequence of anomalies around this same time figure 36, top. Andersen, a professional photographer, visited Anak Krakatau February The eruption earlier in the month had resulted in a new lava flow on the SE flank figure 37 where the September lava flow was located. He observed that "The new layer of lava-flow is black, compared to the red color of the lava flow.

The lava flow has cooled down since the material was deposited. Further, Andersen noted "After having studied aerial views of the crater area figure 38 , it seems that the source vent of the new lava-flow, is the same vent main, central vent that was involved in the eruption.

On the top of the vent, it now seems to be a lava-dome A comparison of photos from October and February composed by Andersen showed the morphological changes during that time, including the new dome and lava flows figure Incandescence was obvious at night figure 40 and from aerial observations of the lava dome Andersen noted that the area with incandescence was small, and that "the lava dome did not appear to be overly active.

Now the main crater is filled with material, with two lava flows originating from this vent running down on the SW and E flanks. On the northern side of the summit an eruption vent is also clearly observed Strombolian, lava flow, and explosive activities resume, June-October Krakatau volcano in the Sunda Strait between Java and Sumatra, Indonesia experienced a major caldera collapse, likely in CE, that formed a 7-km-wide caldera ringed by three islands see inset figure 23, BGVN Remnants of this volcano coalesced to create the pre Krakatau Island which collapsed during the eruption.

The post-collapse cone of Anak Krakatau Child of Krakatau , constructed within the caldera has been the site of frequent eruptions since The most recent event was a brief episode of Strombolian activity, ash plumes, and a lava flow during the second half of February Activity resumed in late June and continued through early October, the period covered in this report.

After the brief event during February , Anak Krakatau remained quiet for about 15 months. Increased seismicity on 18 June was followed by explosions with ash plumes beginning on 21 June.

Intermittent ash emissions were accompanied by Strombolian activity with large blocks of incandescent ejecta that traveled down the flanks to the ocean throughout July.

Explosions were reported as short bursts of seismic activity, repeating multiple times in a day, and producing dense black ash plumes that rose a few hundred meters from the summit. Similar activity continued throughout August, with the addition of a lava flow visible on the S flank that reached the ocean during August.

Generally increased activity in September resulted in the highest ash plumes of the period, up to 4. PVMBG reported significantly increased numbers of daily explosions during the second half of the month. The thermal signature recorded in satellite data also increased during September, and a large SO2 plume was recorded in satellite data on 23 September. Activity during June-July Foggy conditions hampered visual observations during June, but on 21 June gray plumes were observed rising m above the summit figure Two ash plumes were reported on 25 June; the first rose to about 1 km altitude and drifted N, and the second rose to m altitude and drifted S figure PVMBG reported that during July there were four additional ash-producing events, each lasting between 30 and 41 seconds.

The last three of these events produced ash plumes that rose m above the crater rim and drifted N and NW. They were intermittently visible in satellite imagery when not obscured by meteoric clouds. They were essentially continuous until they gradually decreased and dissipated early on 17 July, rising to 1. Satellite imagery revealed hotspots several times during July; they ranged from small pixels at the summit 9 July to clear flow activity down the SE flank on multiple days 12, 19, and 24 July figure Activity during August-early October A series of at least nine explosions took place on 2 August between and local time.

They ranged from 13 to 64 seconds long, and produced ash plumes that drifted N. Continued explosive activity was reported by local observers during the early nighttime hours of 3 August figure The ash plume drifted SE then S the next day before dissipating. Emissions were reported intermittently drifting W on 11, 14, and 16 August at 1.

PVMBG reported black ash plumes drifting N at m above the summit on 17 and 18 August after explosions that lasted minutes each. VONA's were issued during August reporting at least three explosions that lasted seconds and produced ash plumes that drifted N and NE. Ash plumes drifting N and NW were visible in satellite imagery during September at 1. The following day, the plume height had dropped to 1. A hotspot was reported on 12 September. Ash plumes continued to be observed through 13 September.

The ash plume was no longer visible on 18 September, but a hotspot remained discernable in satellite data through 20 September. PVMBG reported incandescence at the summit and gray and black ash plumes on 20 September that rose m above the summit. A low-level ash emission was reported drifting S on 21 September and confirmed in the webcam. Four VONA's were issued that day, reporting explosions at , , , and , lasting from seconds each.

PVMBG subsequently reported observing 44 explosions with black ash plumes rising m above the summit, and incandescence at night on 21 September. Ash emissions continued on 22 September at 1. The plume height was based on and infrared temperature measurement of 12 degrees C. Later in the day, an additional plume was observed in satellite imagery at 3. PVMBG reported observations of 56 explosions, with m high above the summit black ash plumes and incandescence at night on 22 September.

Observations from nearby Rakata Island on 22 September indicated that tephra from incandescent explosions of the previous night mostly fell on the flanks, but some reached the sea. A lava flow on the SSE flank had also reached the ocean figure New eruptions at the volcano since have built a new island, called Anak Krakatau child of Krakatoa. Origin and spelling of the name The earliest mention of the island in the Western world was on a map by Lucas Janszoon Waghenaer, who labelled the island "Pulo Carcata.

There are two generally accepted spellings, Krakatoa and Krakatau. While Krakatoa is more common in the English-speaking world, Krakat au or Krakata o in an older Portuguese based spelling tends to be favored by Indonesians. The origin of the spelling Krakat oa is unclear, but may have been the result of a typographical error made in a British source reporting on the massive eruption of Theories as to the origin of the Indonesian name Krakatau include: Onomatopoeia, imitating the noise made by white parrots that used to inhabit the island.

From Sanskrit karka or karkata or karkataka , meaning " lobster" or " crab". From Malay kelakatu , meaning "white-winged ant ".