Early October data from tilt stations and EDM lines showed no deformation above noise levels since the last measurements in Geologists climbed the volcano on 8 October and noted more vigorous activity at existing fumaroles, plus new vents, an expansion in the size of the fumarole field, and recently killed vegetation.
Hall and H. Banks and J. Ewert , USGS. After 15 months of quiet, phreatic activity began on 16 April at The activity was confined to the phreatic crater formed in , on the NE side of the m-diameter dome that occupies most of the caldera floor.
Activity began with spasmodic harmonic tremor of small to intermediate amplitude, accompanied by strong fumarolic emissions generating a vapor column that rose at least m. Several explosions were heard and recorded by seismographs 1. Seven new fumaroles were observed within the crater, but by 17 April had joined to form a single fumarole 4 m in diameter. Non-juvenile material, rocks, and mud were thrown outward to m from the vent, forming a layer 4 cm thick.
Precursory activity began with a M 2. Only a few small events, both A- and B-type, were detected during subsequent days. The tremor had a typical frequency of 1. Periods of tremor lasted as much as 3 hours, separated by intervals of low-amplitude tremor or quiescence. Intermittent explosions were also recorded, always associated with tremor. Only a few very small B-type events have been recorded since the onset of phreatic activity.
Given the shallow character of the activity, geologists believed that it was partly related to the previous week's increased precipitation. The Instituto's hazard map and previously planned preparedness exercises for a hypothetical eruption of Guagua Pichincha were helping civil defense authorities to prepare for the possibility of increased activity. An area of fumaroles was observed on the central dome figure 4, top where numerous vents, to 30 cm in diameter, were emitting white steam-rich gas with a strong sulfurous smell.
Some yellow sulfur deposition was occurring. Another area of fumaroles was observed on the S wall of the crater figure 4, bottom where individual vents were smaller than those on the dome, but were reaching higher temperatures. Some vents were emitting hot water, while others had pools of boiling mud. Gases from the S-wall fumaroles were the same as those emitted from the central dome fumaroles.
The hottest vent was also the loudest. Information Contacts: S. Hodges , University of Oxford. The Oxford field team also included J. Bass, S. Crampton, J. Dinares, S. Hart, R. Hartley, C. Mandeville, M. More, K. Ogden, J. Scarrow, and A. Based on seismicity, a warning of possible activity had been transmitted to them by radio at , but for unknown reasons they were still on the dome when the eruption occurred.
Search and rescue operations were initiated late that afternoon and at about the following morning their bodies were discovered by M. Hall near the dome's crater rim. Guagua Pichincha had been quiet since phreatic activity April-June The main fumarolic vents on the S side of the dome and the major steam vents at the foot of the S caldera wall exhibited normal fumarolic behavior. Fumarolic activity in the active crater on the NE flank of the dome has been variable but low.
Evidence of recent phreatic activity that had blasted ash and rocks NE against the inner wall of the caldera was noted during routine fieldwork on 11 March. A guard stationed near the caldera rim confirmed that an explosion had occurred on 9 March, depositing up to 10 cm of non-juvenile ash. The Instituto officially advised Civil Defense early on 12 March that Pichincha had resumed dangerous activity and that tourists and mountaineers should be advised of the danger in entering the caldera.
As in past explosive cycles, phreatic activity seems to be related to the rainy season, which normally begins in March. Activity may have begun earlier this year because of the abnormally high rainfall in February.
During March-October a series of phreatic explosions took place within Guagua Pichincha's caldera figure 5. No precursory signals were detected prior to the activity. The intensity of these explosions peaked in May ; the last explosive signal was detected on 18 October This activity resembled phreatic explosions that occurred in , , and Larger explosions on 15, 16, 18, 20, and 22 May, 22 and 23 July, and 18 October were detected by four short-period seismic stations located around the volcano.
Tremor signals following these explosions had reduced displacements of 2. The largest explosion occurred on 29 May at ; its signal was recorded at eight sites, including seismic stations at the volcanoes Cotopaxi 58 km away , Cotacachi 60 km away , and Cayambe 70 km away. The accompanying tremor signal had a reduced displacement of 8.
An A-type fracture event located just outside the E caldera rim at 3 km depth preceded the explosion. Following the 20 May explosion, volcanologists observed two new, white, m-tall fumarolic plumes rising from the explosion crater.
The crater showed evidence of recent collapses on its interior S and SW sides. Fine pulverized rock deposits covered more than 2 km 2 in the N part of the caldera bottom. Blocks up to 50 cm across were scattered over the caldera floor as far as 1 km from the crater; impact craters up to 2 m in diameter were formed. No juvenile material was found.
During , the number of events at stations close to the caldera remained at normal values except during September-October, when a large number of events were detected at stations 1.
However, at stations over 10 km away, the number of events remained at normal values. Low seismicity preceded phreatic activity in and This was the first such swarm detected at Guagua Pichincha since continuous seismic monitoring began in EDM deformation monitoring of the phreatic crater and outer flanks of the dome revealed no change with regard to the baseline established in Thermocouple measurements of fumarole temperatures on the dome showed values of Analyses of spring water from the caldera and the surrounding area gave essentially the same results as in On 4 August during the course of this swarm a M 7.
The eruptions continued through at least early October when they prompted local front-page news stories. As this report went to press in early October, the hazard status was Yellow, the second stage in an alert scheme of White, Yellow, Orange, and Red. During successive months of the swarm's progression, earthquakes became more numerous. Scientists located about 10 of the swarm's events of local magnitude 4. When these hypocenters were plotted on a vertical section oriented SW-NE, no lateral offset was visible, implying that the foci of these larger, located earthquakes rose vertically over time.
An active compressional fault along the Quito's E margin the Quito fault dips W beneath the city and underlies both volcanoes at depth. As noted above, the located earthquakes did not appear to follow the W-dipping fault, and epicenters trended oblique to the fault's N-S surface trace as they defined a zone aligned NW-SE. Still, the swarm was interpreted as tectonic, associated with the Quito fault. The M 7. The U. Geological Survey made a preliminary assessment of the 4 August earthquake as Ms 7.
The earthquake occurred at GMT ; the preliminary depth was given as 33 km. Phreatic eruptions began at on 7 August; others followed into early September. Seismic signals indicated that in some cases eruptive degassing persisted up to 25 hours, type-A earthquakes occurred, but tremor was rare.
The eruptions discharged gas, mud, and lithics, but no juvenile tephra. A veneer of these deposits appeared over the N crater floor when photographed on 15 September figures 7 and 8. At that time, the crater's post dome gently steamed. The dome's N surface lay beneath a veneer of material deposited during and after phreatic eruptions on 7 August. The veneer contained mud and lithics but no juvenile tephra; some of this material formed small lahars that traversed around the dome and spilled out of the crater figures 7 and 8.
A visit to a crater overlook on 15 September disclosed that just beyond the rim of the explosion crater's N side, some new fractures arc around its circumference arrow, figure 8.
This phreatic episode lacked non-seismic precursors. EDM on the crater walls, on the SE flank, and on the dome showed relatively little change. The crater, however, was judged too dangerous to enter for the purpose of obtaining in-situ gas samples. During the first week of September seismicity consisted largely of A-type events, although some long-period events registered and meager tremor was seen. Degassing was too small to produce a conspicuous plume.
On 6 September Quito residents felt two earthquakes; they were M 3. Long-term trends in Pichincha's overall seismicity and explosion-type earthquakes were plotted through August figure 9 ; however, the earthquakes comprising the seismic swarm discussed above were omitted. The prominent seismic peak during coincided with the installation of a new telemetered seismic system just prior to an interval when fumarolic areas expanded, when fumarolic vigor increased, but when no phreatic eruption discharged SEAN Interestingly, the increases also occurred in conjunction with a seismic swarm, in this case on the volcano's S flank km from the summit; associated hypocenters were at km depth.
Phreatic activity took place in , , and , and then again in , , , , , and figure 3 and SEAN , , ; BGVN , , , , and The volcanic crisis near Quito figure 10 continued with a series of phreatic discharges and an E-dipping zone of earthquakes that rose to within a few kilometers of the surface figure 2. With potentially dramatic significance to Ecuador's Capital urban population, 1,, residents; suburban, , residents , the eruption has spurred a strong educational response in both the regional press and on an official web site.
These discourses have repeated noteworthy points: the volcano's last vigorous eruption was in ; its recurrence intervals have oscillated between about and years; its last major eruption took place years ago; and its phreatic eruptions have repeated during the past 15 years. Activity and observations. The epicenters of located earthquakes during April-October generally clustered around the caldera figure This was particularly the case for volcano-tectonic VT earthquakes, which in cross-section view tended to lie underneath the caldera.
The located long-period LP events generally propagated from greater depths and in cross-section view defined a broad E-dipping zone.
Thus far in the crisis there has been an alternating pattern of seismicity and seismically detected explosions figure During late September through late October there were often daily explosions. On 3 October observers confirmed the presence of new fumaroles on the dome's W edge; nearby, in the headwaters of the Rio Cristal, they noted a new fumarole field.
A phreatic explosion was heard at on 5 October by residents of Lloa. The explosion was the thirty-first such event in the sequence initiated on 7 August. It ranked among the most energetic seen to this point of the crisis, comparable to those on 8 and 24 August, and 29 September. Small seismic events continued until that day. This explosion left a fresh ash layer in the caldera that revealed a new vent near the older one but above it to the S.
Measured deformation was not detected for the interval 15 September-7 October. Although not plotted, tremor has occurred. On 11 and 12 October tremor followed phreatic explosions and in the former case, prevailed for 20 minutes at stations near the crater. Roughly 20 people were evacuated. On 12 October condensing gases escaping the dome at a fumarole called "La Locomotora" rose m.
Around this time the explosion crater also emitted a moderate flow of gray gases but new fractures or fumaroles were absent. Clear weather enabled residents of Quito to see the plume.
Geophysical instruments detected the event at widely scattered locations. Guards at a local observation post smelled strong sulfur, particularly when gases from La Locomotra fumarole blew past.
Again, Quito residents saw the plume, but an explosion the next morning was shrouded from view by weather clouds. A 17 October explosion was shrouded in clouds. The phreatic explosions on 14, 15, 16, and 17 October yielded respective reduced seismic displacements of 11, 4. A view into the caldera on the morning of 18 October disclosed relatively passive outgassing from the and explosion craters.
Another moderate explosion on 25 October was followed by 3 hours of tremor. Minard Hall also recognized that the crater and one formed in September had coalesced. The wall isolating them had apparently been weakened by repeated phreatic eruptions. Risk mapping. The highest risk settlements include Lloa figures 1 and 4 and Mindo. The latter lies on the river of the same name about 22 km NW of the caldera; it lies off of maps in this report but is depicted on the larger hazard map of Hall and von Hillebrandt One branch of the Mindo river's headwaters begin just N of the breach in the caldera figure 4.
Rivers draining the breached W-flank and nearby NW-flank e. Rio Cristal and Rio Mindo were assigned a higher category of risk for lahars than any lahar-risk zones on the E flanks figure 1. New fieldwork has been aimed at inspecting older lahar deposits in vicinity of the settlements of Mindo and Nono.
The following describes some of the civic and media efforts to communicate volcanic hazards. In overcast conditions on 24 August a film crew from TeleAmazonas shot footage of an explosion plume not otherwise visible in Quito. These glimpses, and later examples of widely visible plumes, surely helped residents grasp the immediacy and some of the power of the eruption.
Authorities raised the hazard status to Yellow on 1 October. On 3 October a new video system started to monitor the inner crater. This advance was supported by "Ecuavista" in coordination with " of the City of Quito," the phone number for the City's communications base.
A 2 October announcement told of a downtown Quito information center implemented to release daily circulars at bearing official volcanological information. Thanks to a partnership between the information center and IBM of Ecuador, the former gained access to the internet, email, and a modern computing environment The radio station "Zaracay," which can be received widely, including the urban and Mindo areas, was also designated as a conduit for public announcements.
By 7 October the seismic network consisted of 12 stations with real-time data transmission. Collaborating scientific teams and monitoring equipment have come from both the U. Contingency plans have surfaced, dealing with the issue of transportation during the higher stages of alert Orange and Red. Public announcements have broached the need to maintain the integrity of the municipal infrastrucure in the event of an eruption, including crews to clean ash from roads, power lines, etc.
Hall, Minard, and von Hillebrandt M. Geological Survey, MacArthur Blvd. Crisis continues into November; many days with one phreatic explosion. A substantial number of days were marked by one phreatic explosion. Visible explosions rose at most a few kilometers above the summit. Many explosions were accompanied by tremor; they were seismically characterized with reduced displacements. Table 1. Some details of Guagua Pichincha's phreatic explosions, their size as reduced displacements , and associated tremor, 27 October through 17 November A "--" signifies the data is either inapplicable or not reported.
As illustrated in the previous report BGVN , volcano-tectonic, long-period, and multiphase earthquakes all escalated prominently during mid-September. During the current reporting interval, these remained elevated but did not increase, and the numbers of the various events, particularly volcano-tectonic and multiphase earthquakes, may have moderated or diminished slightly. The number of explosions in a single day reached a new high for this crisis: four occurred on 7 November.
The previous one-day record, three, had occurred only on two days in mid-October. Yet, the 7 November blasts were followed by four consecutive days with no explosions and, during November no day had more than one explosion. As an indication of the pace of the venting, during 7 August-3 November the daily reports noted 59 explosions.
The highest plume seen during the reporting interval came from an explosion at on 3 November. Clear atmospheric conditions enabled residents to see it from the city of Quito. Although atmospheric conditions frequently blocked visibility, local observers saw fumarolic plumes rising from to m. Thus, on 28 October a plume rose m; on 9, 11, and 14 November, respectively, plumes rose , , and 1, m high. A plume on 4 November was of ambiguous origin, but it rose 1, m. As late as 16 January, the volcanic crisis near Ecuador's capital, Quito, continued as visually observed activity and seismic indices showed little sign of either halting or escalating.
In addition to photos and regular updates, the site discusses such topics as civil defense and hazard planning. This summary covers the interval 28 October January Summit observations on 27 October disclosed fumaroles off-gassing at both the crater and the adjacent crater, and steam wafting to m.
The last few days of October were marked by comparative quiet, with few phreatic eruptions, and associated tremor under 30 minutes in duration. During 22 November through 22 December instruments detected very few explosions. A visit to the crater area on 20 November disclosed abundant fresh debris on the rim, and numerous impact craters scattered about the area.
Poor weather prohibited systematic determination of ash plume heights, but on 23 December one plume rising to 3 km altitude was seen from Quito. Explosions then resumed, with three explosions on 10 January. Patterns in the number of daily multiphase, long-period, and volcano-tectonic earthquakes were somewhat similar, with lows in the weeks surrounding 28 November and significant upswings thereafter. Many seismic events were shallow, at depths of several kilometers.
Intervals of spasmodic tremor up to two or three hours also occurred during the reporting interval. Scientists computed reduced displacements of the seismically detected explosions.
For the following intervals the maxima can be summarized as follows: November, Two so-called "tornillo" screw-type seismic events were noted on 3 January.
The term arises from the seismic record of these events that looks like the profile of a screw. The broad, higher amplitude portion of the screw occurs early in the arrival sequence; the signal's amplitude decays slowly, finally reaching background at the point of the screw.
On 13 November field workers observed deposits from mud and debris flows that had come down the Cinto and Cristal rivers on 4 November. Triggered by a small rockslide on the SW flank, these flows were also seen by WSW-flank inhabitants who reside in the village of La Playa.
The flows could be observed up to 15 km from the crater. The flow material also mixed with thin ash produced during phreatic explosions. On 19 November a guard at a local refuge reported an absence of activity at both the crater and fumaroles; however, at that day, the fumarole known as 'La Locomotora,' located on the caldera's S wall, expelled vapor reaching m high.
This fumarole remained active throughout the reporting period. Another fumarole, known as Las Alineadas, escaped from the S dome area and was briefly mentioned on several days during mid-December as the source of sulfurous gases and loud noises; on 26 December Alineadas discharged an m-tall vapor plume. On 13, 14, and 16 January crater fumaroles gave off vapor plumes that reached 1 km in altitude.
Press reports. An unusually clear, though undated photo of the two intracaldera craters can be found at the El Comercio website. The same site has over 70 articles in Spanish devoted to Guagua; pieces that are direct, practical, informative, and—given the circumstances—surprisingly upbeat.
They convey a sense of the human side of a volcanic crisis without undue sensationalism. Topics include: broccoli growth in the volcano's soil, the vulnerability of a local marketplace in the event of an eruption, "Geophysicists—the volcano doctors," "Gasoline: there is a distribution plan," and the merging of art and science in an attempt to glean past eruptive behavior.
One article, titled "Guagua: mud and ash could effect 31,," discusses the poor state of roofs in 18 separate zones in N upland areas along the E half of Quito's urban margins, an area described as high-risk.
An impressive figure illustrates the locations and names of the zones, their populations, and shows how each ranks in terms of relative risk from mud flows and ash fall. Finally, for each of these zones, the figure indicates the average estimated risk of roofs to weight-bearing loads. Moderate seismicity and phreatic eruptions during January-February.
This volcano consists of a 2-km-wide caldera, breached to the west, on whose floor lies a dome complex and the present explosion craters. The following report summarizes their daily observations from 1 January to 31 March During this period, a Yellow alert status persisted. Bad weather often prevented or hindered visual observations. Guards at the refuge station and visiting scientists frequently reported noises and the strong smell of sulfur from the fumaroles.
Ash-and-steam plumes from dome fumaroles, when visible, ranged from to m in height, while explosion plumes reached 3 km. The explosion crater had increased in diameter and almost absorbed the September crater. People living along the Cristal river W flank confirmed the seismic detection of small debris flows and floods that were generated on 7 and 27 January, 2, 16, and 21 February, and 1 March, all related to intense rainfalls; these traveled down the Rio Cristal at least km.
Estimated volumes are between 0. Phreatic explosions covered the dome and the interior of the caldera with ash and rocks. A guard at the refuge station and Civil Defense personnel found mm of new ash and new impact craters in the Terraza area following the explosions of 21 and 23 January.
Analysis of the ash showed no juvenile material, suggesting that magma had not ascended. Ballistically ejected rock fragments up to 30 cm in diameter were found Volcano-tectonic VT , long-period LP , and hybrid earthquakes, sometimes in multiples, occurred almost daily throughout January, February, and March.
Phreatic explosions were frequent during that period, occurring on average once per day in February and March. Still, 24 VT events occurred on 28 February and 1 March. High-frequency tremor episodes of a few minutes to as much as four hours 9 February duration were recorded, but possible associated effects in at the caldera summit could not be confirmed due to bad weather. Some rockfalls in the caldera were heard by the refuge guards while tremor episodes were occurring.
On 9 February and 14 March instruments detected 16 and 70 tectonic earthquakes along the N part of the Quito fault. The largest events had magnitudes of 3. It had been speculated that these events represented sympathetic responses to stresses produced by the volcano's magma chamber.
This idea came from an earlier observation of an "on-off scenario" where the presence earthquakes in the N Quito area correlated with little seismicity registering under the caldera, and vice versa. Reduced displacement measurements RDs of phreatic explosions ranged from those too small to measure to several that were 20 cm 2 or greater. Some of these larger RDs, such as those on 18 and 28 January, and 13, 19, and 28 February, were the largest since October The one on 28 February was the largest yet recorded.
A summary of seismic events since August is presented in table 2. Table 2. Monthly summaries of explosions and seismic events at Guagua Pichincha, August March Summary of activity in April; tremor for extended durations; phreatic explosions.
The following summarizes their daily observations for April Ash-and-steam plumes from dome fumaroles, when visible, ranged from to m in height, while explosion plumes reached 1 km. A summary of monthly events since August is presented in table 3. Volcano-tectonic VT , long-period LP , and hybrid earthquakes, sometimes in multiples, occurred almost daily throughout April with the daily numbers increasing substantially during the latter third of the month.
Similarly, two-thirds of the 18 phreatic explosions PE occurred during the last week of April. Rain and mist are almost certain.
Be careful when climbing in wet and misty conditions. The rock can become very slick and the visibilty poor. Take care to remember the way down or be with someone who knows the way. Minor corrections: -Change "Teleferico" to "Teleferiqo" -Teleferiqo drops passengers off at about m, according to a sign near the trailhead.
The photo of Padre Encantado on the overview page isn't correct. This is a peak called Cundur Huachana, which is also accessible via the normal route to Rucu. My undestanding is that Cruz Loma is the viewpoint at the top of the Teleferiqo. As an alternative to the Teleferiqo, there is a pretty easy-to-find route which starts in the "Parque Miraflores", just north of the San Juan tunnels.. Took us about 3 hrs starting in Miraflores to get to the top of the Teleferiqo. Hello - Thank you for your helpful post.
I was hoping to tap into your expertise I am one of four guys headed to Quito in July. This is why I thought Rucu, starting from the top of Teleferico, would be an appropriate choice. Now the questions Our plan is to spend 2 days in Quito, then 2 days at an Ecolodge at a lower elevation, then back to Quito for 3 days. If we do the hike on the 3rd day once we return to Quito, do you think that altitude sickness will be a real threat?
Your description was perhaps the best so far. Just wondering if you think it really is self-evident or if there is more directional information we will need.
I really appreciate your help!! Best, Greg. Dear Dielotr and all other colleagues. Del fr. Se emplea principalmente para salvar grandes diferencias de altitud. And for those with neighborhood safety concerns, taxi cabs are exceptionally reasonable in cost to skip the tougher areas. Flagging a cab in Quito is fast and easy. Can climb any day of the year, unless raining or storming heavily. Teleferico ticket office opens approx.
The best time to be there and climb is at opening. Storms and lightning occur often around p. People do quick-climb Rucu with one night's acclimatization, but any delay around the summit could put one in major danger. The easy route is pretty straightforward, hiking on the ridge for around 1 hour minutes, then the only trail goes around and to the right north of the ridge for 30 minutes, finally up all the loose sand. Since the trail has migrated 80 meters to the right west because of the thousands of people coming down, it is important to remember that an 80 meter left East trail traverse is needed as one approaches the summit or you will end up on the rock west of the summit.
This was followed by 16 hours of continuous tremor. A warning of possible activity had been transmitted to them by radio at , but for unknown reasons they were still on the dome when the eruption occurred. This was the first eruptions in years at the volcano.
A plinian column deposited ash and pumice over Quito, and plunged the city into darkness. Pyroclastic flows and surges overrode the southern and eastern rims of the crater.
The topographic relief of Rucu Pichincha prevented flows from reaching Quito. Historical activity of the volcano has included large explosive eruptions some of which produced sub-plinian and plinian eruption columns, lava domes. Guagua Pichincha volcano's eruptions frequently produce dangerous pyroclastic flows. Following a year long interval of being dormant, Guagua Pichincha volcano has entered a new phase of low seismic, phreatic and magmatic activity in Show interactive Map.
Last earthquakes nearby. View recent quakes. The eruptions were preceded by a magnitude 4. The eruptions ejected blocks m from the vent. Long-period and volcano-tectonic earthquakes and continuous background tremor were recorded until 17 October. Source: GVP monthly reports. There were ash eruptions on 18, 31 March, and 25 May The explosion on 25 May produced a ash cloud reaching an altitude of 8.
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