6-km radius Danger Zone may be extended to 7 km in the sector where the crater rim is low. Hydrothermal, magmatic, or tectonic disturbances may be underway. Alert levels for Mount Pinatubo, May 13, 1991. This means a MAJOR volcanic eruption is imminent. No eruption in foreseeable future. This site uses cookies and third-party service to analyze non-identifiable web traffic data. The question remains, would this percentage be as large should there be a call for evacuation of areas beyond the 10-km radius? Pinatubo began feeling earthquakes and after several explosions a Level 5 alert was issued indicating an eruption was in progress. In 1991, the failure of 18 percent of the respondents to receive preeruption warning before June 12, the failure of 14 percent of the respondents to receive an evacuation order at any time (even after the June 15 eruption), and delay in the receipt of evacuation order by 26 percent of the respondents all indicate some deficiencies in the transmission system. Because the 1992 survey was confined to the 10- to 20-km danger zone, no respondent was expected to have received an evacuation order. In 1992, 94 percent of the respondents learned of the impending eruption on or before July 14, the day PHIVOLCS issued Alert Level 5 (table 5). Respondents were selected from barangays that lay within 10 km, 10 to 20 km, and 20 to 40 km of the volcano's preeruption summit, radii that formally defined danger zones (fig. When the temporary seismic station installed near the volcano recorded high seismic activity on the first 3 days of operation, April 5-7, PHIVOLCS declared a danger zone of 10 km radius that was centered on the volcano's summit and advised evacuation of the residents from the area. Warning messages were formulated at PHIVOLCS' main office and transmitted simultaneously through the DCC hierarchy, major national and local newspapers, radio and television stations, nongovernmental organizations (NGOs), and directly to the endangered inhabitants. FIRE and MUD: Eruptions and Lahars of Mount Pinatubo, Philippines, edited by Christopher G. Newhall and Raymundo S. Punongbayan, 1996 The review involved two sampling surveys among the affected households: the first conducted within a month after the June 1991 major eruptions and the second during the month following the declaration of Alert Level 5 in July 1992. For improvement, the following findings are particularly important: 1. Respondents were asked if they received any eruption warning and (or) evacuation order, and, if so, when. The volcano's 1992 activities were entirely different from its 1991 eruptions. The Cataclysmic 1991 Eruption of Mount Pinatubo, Philippines, USGS Fact Sheet 113-97. However, those who died constituted a very small percentage of the population at risk, so the resulting bias is deemed insignificant. Intense crater glow. At Alert Level 3, an eruption was unlikely within less than 24 h, but at Alert Level 4 all reassurances of safety was gone--an eruption could occur at anytime (C.G. The overreaction may also be traced, at least in part, to the warning messages released by PHIVOLCS. Hazards in valleys and downwind. In all 60,000 people had left the area within 30 km of the volcano before 15th June. History Mount Pinatubo's summit before the 1991 eruption was 1,745 m (5,725 ft) above sea level, only about 600 m (2,000 ft) above nearby plains, and only about 200 m (660 ft) higher than surrounding peaks, which largely obscured it from view. Extreme hazards to communities west of the volcano and ashfalls on downwind sectors. 2-74C (Pampanga); Report No. 4 or 5 times 10. Activity at the summit may involve sluggish lava extrusion with resultant rockfall. Earthquakes and steam explosions announced the reawakening of Mount Pinatubo in 1991, surprising many geologists because Pinatubo was not even listed in catalogs of world volcanoes. Swelling of edifice may be detected. When one of these volcanoes manifests abnormal behavior, PHIVOLCS interprets its changing behavior and decides whether or not to send warnings and, if so, when. On the eastern side of the volcano, most barangays within the 10- to 20-km danger zone that were sampled in 1992 had only about half of their original pre-1991 eruption populations. Either the information drive launched by PHIVOLCS and other disaster response organizations before the eruption did not reach these respondents or the information campaign failed to drive home to them the magnitude of the threat and the urgency as well as the possibility of avoiding the volcano's fury. Last updated 06.11.99. Magmatic processes or effusive eruption underway, which can progress into highly hazardous eruption. Philippine Institute of Volcanology and Seismology (PHIVOLCS), variously dated, Daily Volcano Bulletins, Pinatubo Volcano, April 7, 1991-December 1992: Quezon City, PHIVOLCS. Ten years ago today (June 15, 2001), Mount Pinatubo in the Philippines erupted with a tremendous force, ejecting vast amounts of ash and gas high into the atmosphere; so high that the volcano’s plume penetrated into the stratosphere. "Mt Ruapehu is an active volcano and has the potential to erupt with little or no warning when in a state of volcanic unrest. Activity More Intense Eruption Probable3. Frequent strong ash explosions. Further increase in SO2 flux. Slight increase in SO2 gas output above the background level. How to incorporate these without making the scheme of alert levels inflexible and too specific remains to be studied. Pinatubo erupted violently in June 1991, killing more than 700 people. Normally, the source of eruption warning should be the entity tasked to study and monitor active volcanoes. The alternative is to consciously dissociate the alert levels from danger zones, define a permanent danger zone, and keep other danger zones open-ended and adjustable. A 40-km danger zone was declared because there was concern about pyroclastic flows from a big eruption and the possibility that a caldera might form. Sustained increase, or sudden drop, of SO. The stratosphere is the layer of atmosphere extending from about 10 km to 50 km (6-30 miles) in altitude. Computation of sampling size, household survey, 1991­92. Background, quiet: No eruption in foreseeable future: 1. Ten years ago today (June 15, 2001), Mount Pinatubo in the Philippines erupted with a tremendous force, ejecting vast amounts of ash and gas high into the atmosphere; so high that the volcano’s plume penetrated into the stratosphere. He noted that Mt. In 1992, PHIVOLCS advised the inhabitants of the 10- to 20-km danger zone to avoid the 10-km danger zone (where some residents would otherwise hunt or gather food or tend farm plots), be alert to possible deterioration in the volcano's condition, and prepare for this possibility. FIRE and MUD: Eruptions and Lahars of Mount Pinatubo, Philippines, edited by Christopher G. Newhall and Raymundo S. Punongbayan, 1996 An evacuation area 20 kilometers (12.4 miles) away from the volcano was established and 25,000 people were evacuated. A level 5 alert evacuation of the 2040 km zone on 14th June. Those warnings provided enough lead time for the beleaguered inhabitants to pack up and run away from the volcano. Mount Pinatubo was an example of Plinian eruption The council even provided vehicles to bring the evacuees to the evacuation centers. Reasons for not evacuating immediately as when advised. Interpretation. how many alert levels are there? B) If trend shows further decline, volcano may soon go to level 1. Activity of Ancestral Pinatubo seems to have begun about 1.1 million years ago and probably ended tens of thousands of years or more before the birth of "modern" Pinatubo. In the case of Mt. Most of them did not want to leave their belongings, crops, and livestock and believed that Apo Namalyari would not let them come to harm. Criteria. Definitive time windows for the occurrence of an eruption, such as "eruption possible within 2 weeks" for Alert Level 3 and "eruption possible within 24 hours" for Alert Level 4, were modified to "within days to weeks" and "within hours to days," respectively. Earthquakes and steam explosions announced the reawakening of Mount Pinatubo in 1991, surprising many geologists because Pinatubo was not even listed in catalogs of world volcanoes. Alert Level. But when Mount Pinatubo started showing signs of restiveness in April 1991, PHIVOLCS had no monitoring at the volcano and, hence, no warning system for the area. Magma close to or at earth’s surface. 2-95C (Tarlac); and Report No. Sustained increases in the levels of volcanic earthquakes, some may be perceptible. Nevertheless, some aspects could still be improved. Hundreds of Aetas with their belongings and work animals lined the roads, waiting for trucks to bring them down to evacuation centers. The responses to evacuation orders (a step beyond warnings) indicate that all the respondents except five (2 percent) eventually evacuated (table 7). If the anticipated eruption would be similar to the June 12, 1991 eruption, then the 10- to 20-km danger zone would be affected, so why should they wait? In the case of the Philippines, this entity is PHIVOLCS. A chain of volcanoes most likely means that a destructive plate boundary must have occurred there, which in fact is what actually happened. Interpretation. The 10-km danger zone, in effect since September 1991, was maintained throughout the 1992 unrest. Describe the 4 alert levels for volcanic eruptions: 1. Elevated levels of any of the following: volcanic earthquake, steam/gas emission, ground deformation and hot spring temperature. The institution of an emergency broadcast system might provide a mechanism for effectively involving media in warning transmission. Mount Pinatubo's continuing activity provides an excellent opportunity to continue the development of the eruption warning system. Ironically, the wording was actually chosen to avoid making specific predictions. The mayor of San Marcelino reported that during rescue operations on June 9, 10 Aeta families opted to stay, believing that the eruption was nothing serious--"para lang daw malakas na bagyo'yan" ("it is just like a strong typhoon") (De Villa, 1991). Eight respondents from the <10-km danger zone who should have evacuated immediately merely took other precautionary actions like preparing for evacuation, seeking additional information, or watching out for further developments. Notable increase in the temperature of hot springs. Quiescence; nno magmatic eruption is foreseen. Small earthquakes swarm (20-180) per day occurred beneath Mt. Gob, Fely, 1991, Rains bring death to Pinatubo evacuees: Daily Globe[Manila], April 22, 1991. Extension of Danger Zone in the sector where the crater rim is low will be considered. The following day (June 10), Clark Air Base, a U.S. military installation near the volcano, was evacuated. In a matter of hours on Sunday, the Philippine Institute of Volcanology and Seismology raised the alert level for Taal Volcano to Level 4 from Level 1 — with Level … Table 9. All monitored parameters within background levels. Among those who took other defensive action (table 9), some overreacted by suspending their normal activities, such as going to school or going to work, for 1 to several days. However, incentives for evacuation such as the availability of relief and emergency resources and the usual outpouring of sympathy might also have inspired the move. Faint/intermittent crater glow. Ground deformation measurements above baseline levels. The 1991 eruption of Pinatubo produced about 5 cubic kilometers of dacitic magma and may be the second largest volcanic eruption of the century. 3rd August 1990 Almost all the respondents received the warning from multiple sources, with PHIVOLCS, the media, and military officials as the most common transmitters. Describe the 4 alert levels for volcanic eruptions:1. Additional danger areas may be identified as eruption progresses. On June 14, this was further expanded to the 30-km radius. Pinatubo remains in alert level 0 which means that the volcano is showing no irregularity in its current state… And thus there is no sign of incoming eruption… Last eruption of Pinatubo Household respondents were randomly selected from lists of household heads provided by barangay leaders, with substitutions when the original respondents were either unavailable or unwilling. Critics of the multipath transmission procedure claimed that had PHIVOLCS stuck to the DCC channel instead of directly dealing with the media, reporters would not have been able to cite it as their source for their false or sensationalized reports. Slight inflation or swelling of the edifice. Low level seismic, fumarolic, other unrest. Low level seismic, fumarolic, other unrest. Recommendations to avoid the 10-km … It performed even better in 1992. Confirmed reports of decrease in flow of wells and springs during rainy season. After two months of emissions and small explosions, a series of major explosions began on June 12. 25 Pinatubo volcano. These respondents recounted that, before the eruptions, the eruption threat and the hazards posed by the volcano had been explained to them by PHIVOLCS and other officials. 1 Philippine Institute of Volcanology and Seismology. In early June, tiltmetre measurements had shown that the volcano was … But, because the evacuation order was an overreaction on the part of the concerned officials and misinformation on the part of the radio announcer who broadcast "warning" of an imminent eruption within 72 h, their noncompliance led to no harm. Much of the rugged land around the present volcano consists of remnants of "ancestral" Pinatubo. Initially, volcanologists considered employing an alert level terminology used at other Philippine volcanoes but opted to design a new one for Pinatubo (table 1). These secondary explosions will occur regardless of alert level. Entry within PDZ must be prohibited. [Household survey, 1991; number of respondents was 69]. This overreaction occurred principally while waiting for the "imminent eruption within 72 hours" that was broadcast by the irresponsible radio announcer sometime before July 14, 1992. Some feared lowlanders would burn their crops and homes. During 2001 the crater lake on Mount Pinatubo reached dangerous levels, and the crater lake changed colour in January 2004. Respondents who received preeruption warning and (or) false evacuation order. Its strengths, as well as its imperfections, provide insights on how other volcano-eruption warning systems could be developed or improved. The Aviation Colour Code is changed to yellow. The latter were from one community that was ordered by the municipal DCC to evacuate but, instead of complying fully, sent only its women, children, elderly, and sickly to the evacuation centers, where they stayed for about 3 months. In 1992, the receipt of a false evacuation order by 8 percent of the respondents is a clear case of discrepancy between the warning message released by the source and the message transmitted to the concerned inhabitants. As of Friday, areas around the volcano still remain on Alert Level 4, which means another eruption could be imminent. The latter group promised to leave as soon as the harvest was done (Gob, 1991). Five stages of volcanic alert were defined, from level 1 (low level seismic disturbances) up to level 5 (major eruption in progress). Respondents from the villages Sapangbato and Margot of Angeles City reported that sometime before July 14, 1992, a popular radio announcer, citing PHIVOLCS as his source, broadcast that Mount Pinatubo would erupt within 72 h. It is interesting to note that the PHIVOLCS alert levels do not include one that indicates that the volcano may erupt within 72 h. The signal with the closest time reference is Alert Level 4, which means that eruption is possible within 24 h. But Alert Level 4 was not used in 1992, as the Alert Level jumped from 3 to 5. The official warning system was unable to reach all residents of the large, 20- to 40-km danger zone during the short, hectic time that that zone was in effect (June 15-18). However, there are hazards. Another possible improvement in the alert level scheme would be to reword the "Interpretations" and specifically the phrase "eruption is possible within 2 weeks [or 24 hours]." A) Probable magmatic intrusion; could eventually lead to an eruption. The lowest is alert level 0 when a volcano is quiet. The eruption plume of Mount Pinatubo's various gasses and ash reached high into the atmosphere within two hours of the eruption, attaining an altitude of 34 km (21 miles) high and over 400 km (250 miles) wide. B) If trend is one of decreasing unrest, volcano may soon go to level 2, From level 4 to level 3 to 2:     Wait 2 weeks after activity drops below level 4. On June 15th 1991, the second largest volcanic eruption of the twentieth century took place when Mt Pinatubo erupted at 1:42 pm local time. But there were still others who refused to be evacuated (Velarde and Bartolome, 1991). It is worth pointing out that all of the respondents contacted by the LAKAS organization showed the exemplary appropriate response. Quiescence; no magmatic eruption is foreseen. Life-threatening major eruption producing volcanic hazards that endanger communities. Probable intrusion of magma at depth, which can lead to magmatic eruption. Before June 12, the date of the first large explosive events, 82 percent of the respondents knew of the danger. After the 1992 experience, revision of the alert levels was in order. Life-threatening eruption producing volcanic hazards that endanger communities. Levels 3 and 4 of the Pinatubo scheme anticipated forecast time windows (2 weeks and 24 h) within which an eruption might occur, and each level had an interpretation of activity. The extrusion of a lava dome on June 7 led to the issuance of a Level 5 alert on June 9, indicating an eruption in progress. Incandescent lava dome, lava fountain, lava flow in the summit area. Activity at the summit may involve dome growth and/or lava flow, resultant rockfall. The concept is not new, and there have been attempts to establish such a system. Shortly after the explosion, a new lava dome is observed 1 km NW of the main crater: new lava is now at the surface, but the viscous lava effectively blocks the gas-rich magma beneath it. Low level seismic, fumarolic, other unrest. A photograph of the eruption of Mt. Magmatic, tectonic or hydrothermal disturbance; no eruption imminent. [Note that the criteria for each alert level are qualitative, not quantitative, and that the "meaning" is not strictly a forecast, but rather, a statement of what might occur. Sporadic explosions from the summit crater or new vents. The respondents were of two types: households (with the household head or an adult household member as respondent) and key informants from among barangay and municipal officials. The number of casualties at the height of the June 1991 eruptions was small (only 200 to 300) despite the violence of the explosions and the vastness of the area affected. The highest level is alert level 5, which incidates that a hazardous eruption is in progress. Some other Aetas did not fare as well. Increasing rates of lava extrusion with increased frequency and volume of rockfall and volcanic gas flux, or abrupt decrease in volcanic gas flux due to plugging of lava at the summit crater or active vent. Sustained increases in SO, Intensifying unrest characterized by earthquake swarms and volcanic tremor, many perceptible. The heightened volcanic alert level on Mt Ruapehu has been described as a "kick in the guts" for one tourism business. Hazardous eruption is possible within days. One Municipal Disaster Coordinating Council (MDCC) official admitted that the council decided to order evacuation of barangays beyond the 10-km but within the 20-km radius (including one community that was already living in a relocation center) on the night of July 15. A) If trend is one of increasing unrest, hazardous eruption is possible within days to weeks. Receipt of eruption warning and evacuation order by date. When Mount Pinatubo blew in 1991 in the Philippines, it was the second largest eruption of the 20th century. Contact: Chris Newhall Of those forewarned, 82 percent took protective action, including 46 percent who evacuated. However, within the group that evacuated, some waited two or more days after receipt of an evacuation order before moving, and some merely evacuated their women, children, and elderly or evacuated but returned. These communities were reached by an information drive that featured the Maurice Krafft videotape on volcanic hazards, which he made for the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI). 13th May 1991 – Alert Level 2. Entry into the PDZ must be prohibited. Another 13 respondents (from the 20- to 40-km danger zone) overreacted by evacuating before they were ordered to do so. Magmatic intrusion to shallow levels of the edifice is driving unrest, with indications that hazardous eruption could occur in weeks. Alcayde, Jerry, 1991, 1876 families move out of volcano area: The Philippine Star, April 22, 1991. Magma is near or at the surface, and activity could lead to hazardous eruption in weeks. Sustained increases in SO2 emission rates, ground deformation/swelling of the edifice. Slight inflation or swelling of the edifice. Therefore, evacuation was recommended only for those who had returned to the <10-km danger zone despite advice against reoccupation of the area. Benefits of Volcano Monitoring Far Outweigh Costs–The Case of Mount Pinatubo USGS Fact Sheet 115-97. Start studying Mt. Danger zones may be expanded to a radius of ten (10) kilometers or more from the summit crater or active vent. 4 levels. The organization ensured that everyone received the warning and evacuation order. Some looked on the relocation site as a kind of "bakasyunan" or vacation home. Notable increase in the temperature, acidity and volcanic gas concentrations of monitored springs and fumaroles. Table 1. Alert Level 2 is issued (Volcano Discovery). The traditional DCC channel would certainly minimize the warning source's need to deal with the media and make it easier to pinpoint responsibility for erroneous reporting. s of the active vent may be included in the danger zone. Much of the rugged land around the present volcano consists of remnants of "ancestral" Pinatubo. Five-level alert scheme for Mount Pinatubo, May 13, 1991. The degree to which the severity of the disaster can be reduced by warning depends on the interplay of the major components of a warning system, namely (1) the source and timing of the warning, (2) the warning message, (3) the warning transmission, and (4) the recipients' response (modified from UNDRO, 1986). The 1991 survey showed that 71 percent of the total number of respondents (234) were forewarned; the remaining 29 percent learned of the hazard on June 12 by seeing the first large explosive events, a fact that indicates some weakness in the warning transmission. All monitored parameters within background levels. In mid-March 1991, villagers around Mt. But other factors, including some features of the alert levels, may have inspired overexpectations and overreactions. The Pilipino translation of the phrase "eruption is possible within. Delays in transmission were reported in all the danger zones. Alert Level. Alert levels and danger zones issued on Mount Pinatubo, 1991­92 (PHIVOLCS, variously dated). ." The revised alert levels allow for differentiation of large and small eruptions. This means a MAJOR volcanic eruption is imminent. Relatively high unrest manifested by seismic swarms including increasing occurrence of low frequency earthquakes and/or harmonic tremor (some events felt). Increasing rates of ground deformation and swelling of the edifice. Wait 12 hours after level 5 activity stops, Wait 2 weeks after activity drops below level 4, Wait 2 weeks after activity drops below level 3, Destructive Earthquakes in the Philippines, Rapid Earthquake Damage Assessment System (REDAS). Low to moderate level of seismic, other unrest  with positive evidence for involvement of magma, Relatively high and increasing unrest, including numerous b-type earthquakes, accelerating ground deformation and rockfalls, increased vigor of fumaroles, gas emission, Intense unrest, including harmonic tremor and/or may “long period” (=low frequency) earthquakes or quiet lava emissions and/or dome growth and/or small explosions, Magma close to or at earth’s surface. In contrast, 13 percent of those who were forewarned either waited for the eruption or ignored the warning; and 5 percent ran without definite destination, prayed, or cried without taking any defensive action (table 6). Eruption columns reached 40 kilometers in altitude and emplaced a giant umbrella cloud in the middle to lower stratosphere that injected about 17 megatons of SO2, slightly more than twice the largest yielded by the 1982 eruption of El Chichon, Mexico. The Mt Pinatubo eruption of 1991 was the second largest eruption of the 20th century. Hazardous explosive eruption likely, possible within hours to days. SO2 emission level may show sustained increase or abrupt decrease. In order to minimize unnecessary changes in declaration of Alert Levels, the following periods shall be observed: From Level 5 to Level 4: Wait at least 24 hours after hazardous activity stops [Note that the criteria for each alert level are qualitative, not quantitative, and that the "meaning" is not strictly a forecast, but rather, a statement of what might occur. The anecdotes from the survey informants, and these news reports, highlight some of the communication and cultural problems with which the warning system had to contend. Pinatubo erupted? Intense unrest, including harmonic tremor and/or may “long period” (low frequency) earthquakes or quiet lava emissions and/or dome growth and/or small explosions. Our survey was conducted among the next nearest population, from the 10- to 20-km danger zone. [Household survey, 1991; number of respondents was 234; EW, eruption warning; EO, evacuation order; cum%, cumulative percentage of the 234 respondents], Table 5. Slight increase in seismicity. Intense unrest, continuing seismic swarms, including harmonic tremor and/or “low frequency earthquakes” which are usually felt, profuse steaming along existing and perhaps new vents and fissures. Pinatubo has been selected as one of 38 emotion-packed pictures of all time by an American online publication. ... Pampanga was among the worst hit by the 1991 eruption of Mount Pinatubo and by the ash that the eruption left behind. But these people changed their minds when they could not read sign boards on the buses that indicated which should be boarded by Villar residents, by Moraza residents, and so on. 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