Information Contacts: A. Pouclet , Dept. Bukavu, Republic of Zaire. Card 30 May Intermittent activity through mid-April. During this latest eruption, some overflowing lava reached the upper edge of the first platform for the first time. After a brief lull of hardly one week, breaking the usual rhythm, the activity began hotly at three main points of the fire circle: two joined spatter cones to the south, one spatter cone to the W, and four or five spatter and cinder cones to the N and NE forming an elongated edifice.
After this, all of the central part of the fire circle sunk by about m. During the last part of the activity, strong volcanic shocks were recorded in the seismological stations of the IRSAC. Effusive eruption towards the SE engulfs two villages; significant number of deaths. Nyiragongo began erupting at about on 10 January, apparently from several flank craters. The eruption was primarily effusive, but a mushroom cloud was reported by the Brussels Domestic Service.
Lava flows, mainly on the volcano's SE flank, are reported to have moved as much as 16 km from the volcano, engulfed two villages, and cut several roads. The eruption had probably ended by 11 January. Most of the 65, residents of Goma, 12 km S of Nyiragongo, fled prior to the eruption because of "incessant" earth tremors.
By the night of January, many were returning to their homes. Estimates of casualties range from none to 2,, the latest 26 January being Activity at Nyiragongo began in early December , when the lava lake rose and covered half of the first platform. Premonitory seismic activity was noted from December 11 see above description of Nyamuragira activity, 14 km NW of Nyiragongo.
The eruption began from five fissure vents at about 2, m elevation on the SE flank. The latter flow blocked a major road, preventing supplies from reaching the area.
About hectares of land and houses were destroyed by the flows. Estimates of deaths range from Information Contacts: U. Ueki , IRS. Investigation shows that lava lake drained through flank fissures. At on 10 January, Nyiragongo's lava lake, present in the main crater since , began to drain rapidly through a system of parallel fissures that opened simultaneously on the N Baruta and S Shaheru and Djoga flanks of the volcano figure 1. Within 1 hour, x 10 6 m 3 of melilite nephelinite lava poured from the fissures.
Mean flow thickness was about 1 m, ranging from a few mm near the fissures to about 2 m at flow fronts figures 2 and 3. No spatter ramparts or hornitos were observed. About 70 persons were killed and left homeless by the lava, which destroyed about 1, hectares of agricultural land. Five days before the eruption, the lava lake had risen to its highest recorded level, partially covering the terraces which had surrounded it.
The rapid draining of the lava lake caused the partial collapse of the terraces, where groundwater flashed to steam, producing a dark gray cloud that rose more than 1 km before being blown towards Goma. Goma was plunged into semi-darkness and most of its residents fled to neighboring Rwanda. Seven hours after the eruption began, lava effusion had completely ended, but fumarolic activity continued.
At on 16 January, a strong gas eruption from the main crater projected a cloud containing little or no solid material to about 1 km above the volcano. At , earthquakes felt on the crater rim preceded the collapse of what remained of the terraces, terminating major gas emission.
Weak fumarolic activity persisted. Further References. Nakamura, Y. Pottier, Y. Tazieff, H. Nyiragongo, January 10th, BV, v. Information Contacts: H.
Tazieff , Paris; M. Krafft , Ensisheim; Y. Pottier , IRS. Information Contacts: M. Krafft , Ensisheim, France. Lava fountaining began 26 June in Nyiragongo's central crater and by 7 July a lava lake covered the crater floor. No activity had been reported at Nyiragongo since the lava lake drained on 10 January On 26 and 27 June, two m-high lava fountains were observed at the bottom of the crater.
By 30 June, only one fountain was active, feeding a very small lava pool. In the center of the lake was a domical lava fountain m high and m in diameter. The fountain and the rim of the lake were bright orange, a color similar to that seen during periods of vigorous fountaining before Based on comparisons with known pre-eruption features in the crater, the lake level was estimated to have risen m between 26 June and 7 July.
Most of the lava seemed to be entering the lake from below, but a very small amount of lava was emerging from a m-diameter vent in the N wall of the crater, about 50 m above the lake surface. This vent had apparently been more active a few days earlier. Earthquakes felt during the night of July shook furniture and formed fissures in old houses in Goma. Krafft , Ensisheim.
The eruption began between and on 21 June when an explosion was heard. By a high, wide, pine-tree-shaped column of white vapor was visible over the crater. The initial period of eruption was apparently phreatic, and was accompanied by continuous explosions.
The initial vent had been submerged, and the lava lake surface was domed 20 m high over it with a m-high fountain in the dome's center. Two new vents were active B and C, top right , one about 60 m above the lake level and N of the now-submerged vent, the other, bright red inside, m above the lake level and NE of its companion. Both had formed hornitos, and were steaming vigorously and ejecting lumps of fluid lava.
A m-wide lava flow descended from the first new vent, a m-wide flow from the second. The flow surfaces were chilled but lava was moving through the tubes into the lava lake. Narrow streams of fluid red lava were running over the surface of the second flow into the lake. The S half of the lake, already chilled, was covered by a fissured black crust. The N half had a moving, striped gray skin, the movements starting where the flow from the first new vent entered the lake.
The bubbling dome of the submerged vent was not visible. All of the central and S parts of the lake were covered by a fissured black crust. The first new vent, now only a few meters above the lake level, was fountaining lava to 50 m and emitting a lava flow that entered the lake from the NE. The second new vent was m above the lake level, still red inside and steaming strongly, but had no lava flow. The edge of the lava lake was molten, and bright orange at night.
The activity of the original vent had ceased by 3 July figure 4, bottom left. The first new vent had built a cone about 50 m high since it became active. Observers on 4 July found the first new vent submerged and forming a large domical lava upwelling about m in diameter and m high in the N-central part of the lake.
The rest of the lake surface was covered with a fissured black crust. The second new vent was steaming and sometimes emitting yellow flames; it had no lava flow.
The lava lake surface lay m below the crater rim and was m wide on 7 July. The domical lava upwelling over the submerged first new vent was m in diameter and m high. The upwelling, the tongues, and a thin line around the edge of the lake were bright orange at night.
The second new vent stood 15 m high and was 40 m above the lake level. It was still steaming strongly and was bright orange at night. During the next 10 days the lake continued to rise. The lava upwelling over the submerged, first new vent flattened and narrowed to about m in diameter. By 15 July the second new vent was only 10 m above the lake level and had breached to the S. A small lava flow from it entered the lake; lumps of fluid lava projected around its cone.
By 17 July the lake level was m below the crater rim. The second new vent was submerged and making a second lava upwelling in the lake, about m in diameter with a central fountain 40 m in diameter and about 20 m high. This upwelling had connected with the one over the first new vent. By 23 July the lake level appeared to have slowed its rise. It was m below the crater rim and m wide.
The NW part was occupied by the two active lava upwellings figure 4, bottom right , the SW one m in diameter with a 40 m-wide, m-high bubbling in the center, the NE one m in diameter with a m-wide, m-high bubbling in the center. A line of moving red lava was visible along the W edge of the lake. Before the eruption, the crater bottom was about m wide and covered with eroded lava blocks m high.
Lava had submerged all the blocks by 3 July, by 15 July the crater bottom was completely filled, and by 23 July the lake was m deep. Maurice Krafft estimated the volume of lava emitted 21 June July at 36 x 10 6 m 3. When the volcano's lava lake drained in , 22 x 10 6 m 3 were emitted.
The eruption apparently was not preceded or accompanied by noticeable seismic activity. A seismic observation on 3 July showed continuous harmonic tremor, interpreted as lava rising in the conduit. Precursor events that were observed included fumarole activity in the crater and along showing the initial and the southern fissure, which had increased significantly since January, and an apparent m uplift of the crater bottom. Krafft , Cernay; N. Zana , IRS. By 23 July, lava from several vents had formed a lake about m deep with an estimated volume of 36 x 10 6 m 3.
By mid-September, the volume of the lava lake had approximately doubled, but the eruption rate was declining slowly table 1. Table 1. Daily eruption rates at Nyiragongo over various time periods between 21 June and 15 September Calculated by M. Geologists climbed to the crater rim on 31 July, 4 and 17 August, and 3 and 15 September.
Between 24 and 31 July, the level of the lake surface rose about 20 m. On 4 August, however, the domical upwellings of lava that had marked the location of the 2 vents beneath the NW part of the lake on 23 July were not active. The entire surface of the lake was chilled and no glow was visible. On 17 August, an area of upwelling about m in diameter and 10 m high was again active over one of the vents.
A geologist descended to the surface of the lava lake 3 September and took samples. In hand specimen, these appeared to have a composition very similar to the melilite nephelinite of the lake. Between late July and 15 September, the lava lake continued to grow, raising its surface an additional m to about m below the highest point on the crater rim.
The zone of upwelling over the active vent was m across and lava fountains reached a maximum height of 70 m. The surface of the more voluminous lava lake was roughly m lower than that of the lake because morphological changes associated with the eruption considerably increased the volume of the crater. Krafft, M.
Paris, serie II, v. Krafft , Cernay. Several journalists reported red glow above Nyiragongo at night. A Dutch doctor who visited the summit.
Another press report on 12 July quoted aid workers who described "spitting fire from parasitic cones and fissures" on Nyiragongo's slopes, but there have been no other reports of lava flows outside of the summit crater at Nyiragongo. Press reports through 24 July continued to mention volcanic "smoke" or "dust" falling in the refugee camps.
Zana, N. Hamaguchi and M. Kasereka , Tohoku Univ; M. For four days around 14 July a dense steam-and-gas plume was visible from Goma, and red glow could be seen at night.
An amateur video taken on an unknown day between 19 and 24 July included a 6-second partial view of the crater that revealed a large very active lava fountain roughly in the center of the crater. A large, flat spatter cone had been built, with a least three large openings in the walls and lava flows radiating from the openings. The entire lava lake was not active. The background was hidden by gases and clouds, making it impossible to determine the elevation of the lava lake surface.
Following the activity, the surface was m below the crater rim. A very strong red glow was again observed above the crater during the night of 29 July.
Very little red glow was reported in early August. Another eruption within the summit lava lake began at about on 10 August. Red glow above the summit could be seen from Goma during daylight as well as at night. Press reports also stated that "ash and dust" had been emitted from the volcano. The increased activity on August and strong red glow visible from the refugee camps caused some concern among the refugees and relief workers.
The primary purpose of the USGS scientists was to evaluate the hazards posed to the ongoing relief operations in Goma, which contained more than one million Rwandan refugees and the large Zairian population.
Specific hazards addressed included the threat of active lava flows to resettlement camps and infrastructure, the threat of volcanic ash to air relief operations, and the threat of CO 2 accumulation to refugees in resettlement camps along the Goma-Sake road. Although the crater floor was clearly visible, no signs of activity were observed. However, during the pre-dawn hours on 20 August, strong red glow above the main crater could be seen.
Seismograms from instruments operated by Zairan scientists clearly showed this eruptive activity. The eruption-related seismicity had ended by 22 August, and no additional red glow was noted. No activity was observed during an aerial inspection the next day, but red glow was again seen early on 24 August. Hamaguchi , Tohoku Univ; J. Casadevall and J. On the night of June, glow above the central crater [indicated] a reactivation of the lava lake. A seismic station on the S slope of the volcano recorded a low-frequency microearthquake at on 23 June that may have coincided with the initial lava outburst; there were no felt earthquakes before this event.
However, tremor activity increased significantly at later that same day. A National Park team that visited the summit reported three active vents inside the crater, the northern-most of which had formed a small scoria cone. On 1 July, four lava fountains were active. Intense lava emission was accompanied by increasing tremor amplitude recorded at local seismic stations.
Continuous activity lasted until about 17 July, but decreased notably after 4 July. Additional episodes of lava lake activity occurred during August, August, and from about on 25 August through the 29th. The rate of lava fountaining. Lava fountain heights of m were also less than the m heights reached in Renewed lava lake activity was preceded by a general increase in amplitude and frequency of long-period volcanic earthquakes. Volcanic tremor and earthquake swarms were recorded on January, 20 January, and 16 May Records from the S-flank seismic station Bulengo indicated increased seismicity in the SW Virunga area; the frequent volcanic tremor and microearthquakes recorded at this station were not recorded at other stations outside the Nyiragongo field.
On 21 November a M 4. This event, felt in Goma with an intensity of MM V-VI, resulted in cracked walls of several brick houses and the death of one woman caused by a falling concrete platform.
There were several aftershocks, and tremor activity was recorded for several days. Information Contacts: N. Lava lake activity has continued. Monitoring is done from a small observatory building located in Goma on the N flank of Mt. Goma, an old scoria cone near Lake Kivu. With the financial support of the Japanese government, the observatory has recently been supplied with electricity, furniture, a vehicle, and other items to make it more functional.
Zairian technical staff and researchers from CRSN-Lwiro maintain the telemetered seismic system and interpret the data. Intermittent active periods within the lava lake, observed several times each month, are characterized by a sharp increase in tremor intensity followed by a gradual decline. Tremor recorded from 8 November until 18 January figure 6 revealed a change in mid-December from active periods of days to more frequent active periods lasting days.
This change in the pattern of active periods is believed by Hamaguchi and others to reflect a change in the hydraulic pressure difference between the magmatic reservoir at depth and the summit reservoir lava lake.
A-type earthquakes recorded during November and December with clear P-phase onset times and moderate amplitudes were clustered along a NNW-SSE strike figure 7 , parallel to the direction of major fissures in the volcanic system. During a UNDHA mission to Zaire on February, John Tomblin and consultant Dario Tedesco met with local government officials, made a hour visit to the crater rim of Nyiragongo, and prepared preliminary versions of volcanic hazard maps of both Nyiragongo and Nyamuragira.
Future work will include improving the hazard map and preparing detailed descriptions of volcanic eruption scenarios. To better prepare for an event similar to , regular measurements are needed.
To establish a baseline for the lava lake, a UN team visited the crater rim on February. During this visit precise levelling measurements were made by theodolite of three vertical profiles up the inner crater wall. Careful observations were also made of the m-wide active lava lake, which exhibited frequent minor explosions that ejected spatter bombs within a m radius and sent lava flows across the entire crater floor m in diameter.
Using an average radius of m for the crater, they calculated an average magma-supply rate of 1. The estimated maximum rate during the historical period was 2. Hamaguchi, H. Information Contacts: J. Hamaguchi , Y. Morita , and S. This activity was characterized by A-type high-frequency and C-type low-frequency events. Depths for all of the earthquakes decreased from W to E and from S to N, suggesting a volcanic conduit rising in a generally NE direction towards the surface on the ESE flank of Nyamuragira.
The level of volcanic tremor was very low. The low tremor level does not signify an overall reduction in the Nyiragongo lava lake activity, but no fresh lava was apparent in the crater.
Seismic recordings in the first half of October were severely impaired by frequent power disruptions to the observatory and the regular discharge of the batteries. The number of earthquakes decreased significantly compared to September; events were mainly centered at greater depths km SE of Nyiragongo. Problems with the transmitter at the Kunene seismic station prevented acquisition of better data; scientists were unable to visit the station regularly due to a lack of tires for their vehicle.
Seismicity during 15 November-2 December remained high, mainly consisting of A- and C-type earthquakes, and volcanic tremor. The distribution of hypocenters was similar to that observed during September. Each series of earthquakes was followed by up to several hours of tremor.
Five seismic stations were operating during this period, four of them Kibati, Rusayo, Buhimba, and Kunene telemetered to the Goma observatory, and the fifth Mt. Goma connected by cable. However, the transmitter from Kunene was intermittent. Tremor amplitude remained low. Goma is the city where the major encampment of Rwandan civil-war refugees is located. A previous lava lake in the deep summit crater of Nyiragongo, active since , drained suddenly on 10 January , killing about 70 people.
Lava lake activity resumed in June , but had ceased by early Historical eruptions from Nyamuragira 14 km NW of Nyiragongo have occurred within the summit caldera and from numerous flank fissures and cinder cones. Nyamuragira also began erupting in July , producing lava fountaining, lava flows, and ash emission. Bukavu, Zaire. No visible activity in April and August; summary of activity.
Members of an SVE excursion who climbed Nyiragongo during the second week of April found no visible eruptive activity. They heard from local residents that the eruption that began in June BGVN had ended in September Whether the eruption actually ceased in September is ambiguous because Dario Tedesco learned that in November and in February-March observers saw glow above the crater at night. Also, Tedesco learned that some tourists spending the night near the summit during this same post-September interval allegedly saw minor activity.
Observations on 3 August Christoph Weber visited the volcano on 3 August and made a rough sketch map figure 9. Weber also saw no new activity and based on discussions with locals concluded that the last eruptions consisted of the lava fountains and lava lake dynamics that took place in the interval July to September BGVN and Features in the crater area included a spatter cone, a feature bordered on its S side with a light gray lava flow dark shading.
This flow was apparently the last erupted prior to the visit and it still showed fresh-looking flow channels. Weber also relayed that seismologist Mahinda Kasereka had seen typical seismicity around this time interval.
Reported activity during November August Tedesco elaborated on activity from November to as late as March , describing almost continuous lava lake activity. The lake lay within the confines of a spatter cone 50 m high and m across.
Lava escaping at the spatter cone's base formed two main flows that expanded into an intracrater depression.
Theodolite measurements, however, indicated that during this interval the crater floor lacked detectible inflation. During this time period the Goma Observatory seismic system registered tremor and local earthquakes tens of kilometers N and W of the Nyiragongo crater. Some time around March to early April activity changed significantly, Tedesco reported.
There were seismic swarms and high lava fountains the latter previously unseen since November , marked effects presumably due to the availability of a fresh batch of undegassed magma. Suddenly, in mid-April the activity ceased for a couple of weeks; the spatter cone disappeared leaving only a much smaller hole located farther towards the N crater wall; inside the hole a solid crust covered the floor.
Tedesco also reported that at the end of April, after a M 5. Two spatter cones formed. The latter estimates were made from oblique photographs, without aerophotogrammetric maps, and by accepting an overall average flow thickness of 1 m for a flow that ranged from 0 to 3 m thick Tazieff, , p.
Eruptive history. A previous lava lake in the deep summit crater of Nyiragongo, active intermittently since , drained suddenly on 10 January Lava lake activity resumed in June with phreatic explosions and lava fountaining, but had ceased by early Tazieff, ; Tazieff, For the past two and a half years this portion of Zaire's border had contained camps with hundreds of thousands of refugees; over a month ago these refugees fled to escape fighting.
Niragongo, Jan. Tazieff, , Nyiragongo, the forbidden volcano translation from French language text by J. Barnard : Barron's Educational Series, Inc. Niragongo: renewed activity of the lava lake: Jour. Lava lake status unclear; new fumaroles and elevated ground temperatures. During the beginning of March , scientists from the Goma Volcanological Observatory visited Nyiragongo in an effort to determine if the volcano was active. At that time the crater was estimated to be , m in diameter. Thus, as this issue of the Bulletin goes to press, it remains uncertain whether Nyiragongo's lava lake's surface remained active and molten, or whether its surface was covered by a thick solid crust.
GVN will try to clarify this in a future report. The scientists observed several changes since January Fumaroles were present on the side of the small central crater.
Cracks observed in the main cone suggested dilatation of the crater area. TOMS observations. Since these concentrations were presumably associated with the eruption of Nyamuragira, they were discussed within that report. On the other hand, the large sizes of these concentration anomalies and the uncertainty of the relevant eruption chronologies make it unclear whether Nyiragongo contributed appreciable SO 2.
Encroaching lava spurred massive evacuations of the city. A great deal of conflicting information exists concerning the numbers of people killed or displaced, the amount of property destroyed, the specific paths of the lava flows, etc. Agency for International Development - Office of U. Numerous dramatic press reports showed multiple lava flows engulfing Goma; city streets became paths for rough-surfaced lava flows, and numerous buildings collapsed, burned, or both.
In the end, one of the flows passed completely through Goma to enter Lake Kivu and proceeded to build a lava delta. The lava flows damaged or destroyed agricultural areas around Goma, covered the N part of the runway at the airport, and cut off access to parts of the town. Lava flows destroyed both residential and business districts as well as a cathedral. Authorities in Goma reported that more than , people remained there during the peak of the lava flow activity.
The start time of the 17 January eruption is uncertain. According to Agence France-Presse, Nyiragongo began to erupt at about Most reports stated that three lava flows moved down the E, W, and S flanks. Two flows traveled directly S through Goma and divided the city in three. One of these flows continued into Lake Kivu. OCHA stated that at on 17 January observers flew over the volcano in a helicopter and reported a large lava flow approaching Goma.
The lava flow cut the road between Goma and Rutshuru to the N, figure By , with a small hill slowing its progress, the lava flow had reached 2 km N of the airport and was still progressing southward. The smaller of the two lava flows heading toward Goma cut the road leading in from the W figure OCHA reported that a fourth fissure opened during the afternoon of 17 January.
A total of 14 neighboring villages were affected by the lava flows. News reports made much about fires in Goma. Fuel depots exploded and kerosene storage facilities at the airport burned. A UN worker in Goma reported that the air was full of ash and dust during the eruption. News reports also emphasized the fires' smoke and soot.
On 18 January, OCHA reported that tremors occurred every hour, and some were strong enough to damage buildings in Gisenyi figure As of 24 January, earthquakes and tremors up to M 4. Although no new lava flows threatened the city, some scientists feared that lava entering the lake or seismic activity could disturb the lake sufficiently to release significant amounts of carbon dioxide and methane gas lying at the lake bottom. News and other scientific sources suggested a gas release was unlikely.
OCHA reported that a 22 January a flight over the volcano confirmed a lack of new activity, including the crater where only a few fumaroles were present. A system of fractures was visible along the southern slope of the volcano, starting from the eastern flank of Shaheru crater close to the main Nyiragongo cone and propagating down close to the outskirts of Goma. The fractures were generally meters wide, and during the eruption lava poured out from different locations and altitudes along the fracture system.
According to OCHA, volcanologists determined that ash observed in Goma on 23 January originated from the collapse of Nyiragongo's inner crater and not from a Nyamuragira eruption, as was originally incorrectly stated in several news reports. During a visit to Nyiragongo's main crater on 28 January, the UN Volcano Surveillance Team found that the crater floor had collapsed more than m.
In addition, they reported no ongoing volcanism nor any fumaroles at the bottom of the crater, although they could smell SO 2.
On 28 January the volcano was at Alert Level Yellow second on a four-color scale. Regional seismicity. On 4 January , an M 4. Local volcanologists had planned to visit Nyiragongo on 19 January to observe its activity, but the volcano erupted before the visit.
According to Bruce W. Tectonic swarms of this size occasionally appear in conjunction with volcanism. For example, seismologists noted intense protracted swarms during Miyake-jima's intrusions and eruptions during the year BGVN , , and The largest earthquake to date in the sequence was M 5; it struck at on 20 January at 1.
The second largest, M 4. Though imprecisely fixed, these estimated epicenter locations are just a few ten's of kilometers WSW of Goma; and the probable uncertainty could place them closer to Goma and Nyiragongo.
The earthquakes contained sharp P- and S-wave arrivals. Also, as would be expected of tectonic events at teleseismic distances, the associated signals at even the closest stations MBAR and KMBO lacked tremor. The signals were not the sort that could be expected to arise from surficial processes like sudden mass wasting, fuel explosions, building collapses, etc.
First motion or minimal tensor results are not yet available. Comparatively few news accounts discussed the seismic activity or seismically induced damage, perhaps because residents were concerned with more pressing aspects of Nyiragongo's eruption. Table 2. The earthquakes were all recorded instrumentally as well.
Stephen Yavorsky, S. As a result of the seismicity, many buildings collapsed in Goma. At least 25 buildings in Gisenyi were also destroyed. Humanitarian crisis. According to OCHA and various news reports, refugees began to return to Goma just a few days after the eruption, despite the dangers that still existed in the area. Aid workers reported that the refugees would rather return to Goma and risk another eruption than stay in displacement camps in Rwanda, which they perceived to be a hostile country.
On 21 January, continuing seismic activity caused buildings to collapse, resulting in more deaths. Poor access to people in affected parts of Goma was a problem for relief efforts. Several humanitarian groups, along with news agencies, reported that aid workers, along with returning refugees, crossed freshly crusted lava flows to access certain areas. You may also like.
From the same country. On the same subject. More stories. Democratic Republic Of Congo. By using this website, you agree with our use of cookies to improve its performance and enhance your user experience. More info in our Cookies policy page. June 19, JPEG. On June 19, , Mount Nyiragongo released a plume. In this image, the blue-tinted plume blows over Lake Kivu toward the southeast. Clouds also hover over neighboring Mount Nyamuragira, to the northwest. Nyiragongo is a stratovolcano —a steep-sloped cone composed of alternating layers of hardened lava, solidified ash, and rocks ejected by previous eruptions.
For five decades, the volcano cradled an active lava lake in its summit crater.
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