MAYON southeastern Luzon, Philippines 13.257°N, 123.685°E; summit elev. 2,462 m; All times are local (= UTC + 8 hours)

Reports from 2001: | January | February | March | April | May | June | July | August | September | November |
Reports from 2002: | February | October-November |
Reports from 2003: | March | May | September | October |
Reports from 2004: | May | July | September | October | December |
Reports from 2005: | August |
Reports from 2006: | February | July |


Mayon Eruption History Information from the Global Volcanism Program

_____________________________________________________________________________________________________________________

3-9 January 2001

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) stated in the 09 January Mayon Bulletin that major monitored parameters strongly suggest that activity is rapidly progressing beyond the usual background conditions at the volcano. Reports by the Ligñon Hill Observatory in Legazpi City disclosed that lava dome growth was occurring at the volcano's summit, with coinciding, slight ground tilt. In addition, voluminous volcanic gases were released from the summit crater, and there was a significant increase in earthquake occurrences for about a week that they believe is related to magma ascent. As of 9 January, near-continuous cloud cover prevented observations of the dome to determine if lava was present in the crater. Because reactivation of the volcano may eventually lead to the production of lava flows or pyroclastic flows, PHIVOLCS put the volcano at Alert Level 2 (increased and sustained volcanic unrest) and maintained the 6-km-radius Permanent Danger Zone.

Sources: PHIVOLCS, Associated Press, Reuters

10-16 January 2001

An aerial survey by the Philippine Institute of Volcanology and Seismology (PHIVOLCS) on 10 January confirmed the presence of a lava dome inside the summit crater. The lava dome appeared to have a spiny, blocky surface, was emitting voluminous steam, and exhibited slight incandescence. The SO2 emission rate was 2,300 metric tons per day (t/d), high above the 500 t/d level usually observed during quiescent periods. Seismicity related to dome growth remained significant. Deformation measured by electronic tiltmeters on the N flank indicated intrusion of magma into the upper levels of the volcano. Similar activity continued through the 15th. Alert Level 2 (sustained unrest with indications of magmatic activity) remained in effect.

Source: PHIVOLCS

17-23 January 2001

PHIVOLCS reported that activity increased at Mayon during the week and that all indicators suggested that the lava dome in the summit crater was becoming active although no new lava had reached the surface yet. During 17 and 18 January, 36 low-frequency-type volcanic earthquakes occurred over 24 hours, which scientists believed was caused by continued magma movement beneath the summit lava dome. During 19-23 January the number of recorded earthquakes increased to 60 events per day; tiltmeters continued to record inflation; and SO2 emission rates increased to 8,070 tons/day (a more than 4-fold increase from that seen in previous weeks). The Lignon Hill observatory reported that ash-entrained steam briefly erupted from the summit lava dome at 0932 on 22 January accompanied by a volcanic earthquake. The volcano remained at Alert Level 2.

Source: PHIVOLCS

24-30 January 2001

PHIVOLCS reported that the increase in volcanic activity, which has occurred since a lava dome was spotted in Mayon's summit crater on 10 January, led them to raise the Alert Level from 2 to 3 (an increased tendency towards eruption, with magmatic outbursts possible within the coming weeks) on 25 January. During the previous week the monitoring networks had detected numerous volcanic earthquakes, continued inflation at the edifice, and very high gas emission from the summit crater (5,040 metric tons per day). In addition, several ash ejections coincided with earthquakes that originated from beneath the lava dome, which appeared to grow during the week. The ash-laden volcanic plumes typically rose up to 500 m above the crater and generally drifted with the prevailing wind to the WNW and NW.

Sources: Philippine Institute of Volcanology and Seismology,

31 January- 6 February 2001

PHIVOLCS reported that numerous shallow earthquakes, high SO2 emission rates, and sustained inflation during the week reflected the active state of the growing summit lava dome. They reported that during the week up to 46 volcanic earthquakes were recorded per day, the SO2 emission rate increased from 2,600 metric tons per day (t/d) on 1 February to 5,330 t/d on 5 February, and electronic tiltmeters on the N flank of the cone continued to detect inflation at the volcano's edifice. Incandescence was visible periodically at the summit. On 1 February, officials recommended that residents of the five towns within the 6-km-radius Permanent Danger Zone evacuate the area. In addition, PHIVOLCS warned residents just outside of the Permanent Danger Zone to be alert for potential hazardous volcanic flows, which may be channeled by rivers and gullies that radiate from the summit. Mayon remained at Alert Level 3 (on a scale of 0-5).

Sources: Philippine Institute of Volcanology and Seismology, Agence France-Presse, Reuters

7-13 February 2001

The PHIVOLCS reported that volcanic activity remained high at Mayon. Abundant low-frequency volcanic earthquakes associated with dome growth took place on 7, 8, 9, 11, and 12 February and consisted of 29, 30, 29, 45, and 30 events, respectively. Also on 12 February seismometers detected 2 rockfalls. The crater emitted voluminous steam and sulfur, with a maximum of ~7,100 metric tons of SO2 detected on 12 February. Tiltmeters on the volcano's N flank continued to detect slight edifice inflation. On 11 February, PHIVOLCS reported that most of the springs in the E and S quadrants of the volcano showed a decrease in discharge, despite increasing rainfall. Inclement weather prevented observations of the volcano. Mayon remained at Alert Level 3 (on a scale of 0-5).

Source: Philippine Institute of Volcanology and Seismology

14-20 February 2001

PHIVOLCS reported that activity decreased at Mayon in comparison to the previous week with a slightly lower number of earthquakes and lower SO2 emission rates. Between 19 and 31 low-frequency volcanic earthquakes were recorded daily during 13-20 February. SO2 emission rates decreased from ~7,100 metric tons per day (t/d) on 12 February, to 2,700 t/d on 13 February. The highest SO2 emission rate recorded during the week was 4,800 t/d on 15 February. During the week there was an inflationary trend at Mayon. The volcano was obscured by clouds so that crater glow and steaming activity could not be observed. Mayon remained at Alert Level 3 (on a scale of 0-5). PHIVOLCS reported that they plan to lower the Alert Level to 2 if volcanic activity continues to decrease.

Source: Philippine Institute of Volcanology and Seismology

21-27 February 2001

PHIVOLCS reported that during the week the number of earthquakes recorded at Mayon was similar to the previous week, and lower SO2 emission rates were recorded. Between 6 and 30 low-frequency volcanic earthquakes were recorded daily during 21-26 February. SO2 emission rates decreased from a maximum value of ~3,000 metric tons per day (t/d) on 20 February, to 1,700 t/d on 21 February. The minimum value was ~1,000 t/d on 24 February. During the week there was an inflationary trend at Mayon's edifice and no incandescence was observed at the volcano's crater. Weak-to-moderate steaming was occasionally observed. Mayon remained at Alert Level 3 (on a scale of 0-5).

Source: Philippine Institute of Volcanology and Seismology

28 February-6 March 2001

PHIVOLCS reported that during 28 February to 6 March, 15 to 50 low-frequency earthquakes were recorded daily. An average of 1,855 metric tons per day (t/d) of SO2 was recorded during the previous week, which was significantly above the baseline value of 500 t/d. A slight inflationary trend was detected at the volcano's edifice, no incandescence was observed at the crater, and weak-to-moderate steaming was occasionally seen. Mayon remained at Alert Level 3 (on a scale of 0-5).

Source: Philippine Institute of Volcanology and Seismology

7-13 March 2001

PHIVOLCS reported that during 7 to 13 March, 6-33 low-frequency earthquakes were recorded daily. One SO2 emission measurement was made during the week on 4 March, with a reading of 1,750 metric tons. Like the previous weeks, a slight inflationary trend was detected at the volcano's edifice and weak-to-moderate steaming was occasionally seen. At 1509 on 11 March a brief ash discharge reached a height of 150 m and drifted to the SW. At 1940 the same day faint incandescence was observed at the crater using a telescope; graded as level 1 intensity. Mayon remained at Alert Level 3 (on a scale of 0-5).

Source: Philippine Institute of Volcanology and Seismology

14-20 March 2001

PHIVOLCS reported that during 15 to 19 March, 10-37 low-frequency earthquakes were recorded daily. An average of 2,900 metric tons per day (t/d) of SO2 was recorded during the previous week, which was significantly above the baseline value of 500 t/d. Many days a slight inflationary trend was detected at the volcano's edifice and moderate steaming was seen. No incandescence was observed at the crater. PHIVOLCS warned that instrumental and visual observations suggested that an eruption may occur in the coming weeks and that the volcano remained at Alert Level 3. Observations revealed that the lava dome growing at the summit had overlapped the pre-existing SE rim of the summit crater. Further growth of the lava dome towards the SE could result in rockfalls and avalanches that would be channeled down the SE-flank Bonga Gully. In addition, large pyroclastic flows could occur down the volcano's SE slope.

Source: Philippine Institute of Volcanology and Seismology

21-27 March 2001

PHIVOLCS reported that during the week ending on 25 March there had been a total of 86 low-frequency volcanic earthquakes with relative amplitudes of 45 mm. The SO2 flux during the same period averaged 2,975 metric tons/day, which is still significantly above the baseline value of 500 tons/day. Deformation monitoring showed that the volcano was inflated, but the present trend revealed insignificant change. The crater was visible, but no glow was observed. Moderate steaming was typical. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone.

Source: Philippine Institute of Volcanology and Seismology

28 March- 3 April 2001

PHIVOLCS reported that during the week ending on 1 April there had been a total of 23 low-frequency earthquakes. The SO2 flux during the same period averaged 2,174 metric tons/day, which is still significantly above the baseline value of 500 tons/day. Deformation monitoring showed that the volcano was inflated, but the present trend revealed insignificant change. The crater was visible, but no glow was observed. Moderate steaming was typical. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone.

Source: Philippine Institute of Volcanology and Seismology

4-10 April 2001

The last reported observations of Mayon by the PHIVOLCS occurred on 6 April. At 0754 a small eruption produced an ash puff that reached 200 m above the crater rim before drifting to the WSW. The same day 17 low-frequency volcanic earthquakes were recorded and ~2,600 metric tons of SO2 were measured, a value significantly above the baseline value of 500 tons/day. Deformation monitoring showed that the volcano was inflated, but the present trend revealed insignificant change. The crater was visible, but no glow was observed. Moderate steaming was typical. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone.

Source: Philippine Institute of Volcanology and Seismology

11-17 April 2001

PHIVOLCS reported that during the week ending on 8 April there had been a total of 116 low-frequency volcanic earthquakes, six high-frequency volcanic earthquakes, and three high-frequency short-duration harmonic tremors. The SO2 flux during the same period averaged 3,400 metric tons/day, which is still significantly above the baseline value of 500 tons/day. Deformation monitoring showed that the volcano was inflated, but the present trend revealed insignificant change. Moderate steaming was typical. During most of the week no glow was observed at the crater, except during 1915 to 2223 on 10 April when faint incandescence was observed at the crater using a telescope; the incandescence was graded as level 1 intensity. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone.

Source: Philippine Institute of Volcanology and Seismology

18-24 April 2001

PHIVOLCS reported that during the week ending on 15 April there had been a total of 60 low-frequency earthquakes and 13 high-frequency short-duration harmonic tremors. The SO2 flux during the same period averaged 3,400 metric tons/day, which is still significantly above the baseline value of 500 tons/day. Deformation monitoring showed that the volcano was inflated, but the present trend revealed insignificant change. Moderate steaming was typical. Faint incandescence was observed at the crater using a telescope for approximately an hour on both 16 and 17 April; the incandescence was graded as level 1 intensity. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone.

Source: Philippine Institute of Volcanology and Seismology

25 April- 1 May 2001

PHIVOLCS reported that during the week ending on 22 April there had been a total of 42 low-frequency earthquakes and 11 high-frequency short-duration harmonic tremors. The SO2 flux during the same period averaged 3,400 metric tons/day, which is still significantly above the baseline value of 500 tons/day. Deformation monitoring showed that the volcano was inflated, but the present trend revealed insignificant change. Moderate steaming was typical. The crater was visible, but no glow was observed. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone.

Source: Philippine Institute of Volcanology and Seismology

2-8 May 2001

At 1848 on 7 May an explosion occurred at Mayon that was recorded by the seismic network on the volcano, but was not observed due to cloudy conditions. After the eruption, faint incandescence was visible at the crater with the naked eye during 1915-1945; the incandescence was graded as level 2 intensity. During the week ending on 29 April there had been a total of 33 low-frequency earthquakes and 12 high-frequency short-duration harmonic tremors. The SO2 flux during the same period averaged 3,100 metric tons/day, which is still significantly above the baseline value of 500 tons/day. Deformation monitoring showed that the volcano was inflated, but the present trend revealed insignificant change. Moderate steaming was typical. The crater was visible, but no glow was observed. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone.

Source: Philippine Institute of Volcanology and Seismology

9-15 May 2001

Volcanic activity increased at Mayon, with a lava dome collapse occurring on 13 May. On 12 May seismographs detected a series of explosions at Mayon's summit crater. The following day the SE-facing portion of the lava dome partially collapsed, leaving a V-shaped opening in the dome. The collapse produced small lava avalanches that reached a maximum runout distance of 300 m down the Bonga Gully. After the collapse, incandescence was observed at the dome and lava fragments fell into the gully. Seismic activity indicated frequent earthquakes, tremor, and explosions. On 14 May rockfalls dominated the seismicity. On 15 May there was a lull in activity, with no rockfalls or lava avalanches occurring. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone. PHIVOLCS warned that lava flows and/or pyroclastic flows could be produced in the future and residents just outside of the permanent danger zone should be prepared to evacuate at any time.

Sources: Philippine Institute of Volcanology and Seismology, Associated Press, Agence France Presse

16-22 May 2001

Elevated levels of volcanic activity continued at Mayon. Rockfalls were produced from fragments that were shed off of the summit lava dome. Seismic activity was relatively low. SO2 emission rates were at a very high level of ~7,400 metric tons per day, which is significantly above the baseline value of 500 tons/day. Moderate steaming occurred and Intensity I (faint) and II (fair, visible with the naked eye) incandescence was occasionally observed at the crater. Weak-to-moderate ash-and-steam venting occurred from the lava dome. Electronic distance meter (EDM) data indicated a general, but minor, inflation of the volcanic edifice. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone. PHIVOLCS warned that residents around the volcano, especially those staying in areas facing the Bonga Gully and the SE sector, should be vigilant and prepared to evacuate at any time.

Sources: Philippine Institute of Volcanology and Seismology, Associated Press

23-29 May 2001

During the week seismic activity was relatively low at Mayon and was associated with occasional rockfalls that descended to the SE down the Bonga Gully. In addition, moderate steaming occurred, incandescence was occasionally observed at the crater, and SO2 emission (up to 5,700 metric tons/day) was above the baseline value of 500 tons/day. On 28 May at 1036 the seismic network recorded a low-frequency volcanic earthquake that was inferred from seismic data to be associated with an ash puff. The ash puff not visible due to meteorological cloud cover. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone. PHIVOLCS warned that residents around the volcano, especially those staying in areas facing the Bonga Gully and the SE sector, should be vigilant and prepared to evacuate at any time.

Source: Philippine Institute of Volcanology and Seismology

30 May- 5 June 2001

During the week a large amount of high-frequency short-duration harmonic tremor occurred at Mayon. The tremor was associated with the intermittent descent of small lava avalanches and incandescent volcanic material down the Bonga Gully on the SE flank of the volcano. Moderate amounts of steam were observed rising from the summit crater where incandescence was occasionally observed. SO2 emission (up to 2,900 metric tons/day) was above the baseline value of 500 tons/day. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone. PHIVOLCS warned that residents around the volcano, especially those staying in areas facing the Bonga Gully and the SE sector, should be vigilant and prepared to evacuate at any time.

Source: Philippine Institute of Volcanology and Seismology

6-12 June 2001

Rockfalls, small avalanches, moderate steam emission, and fair-to-bright crater glow dominated the visible volcanic activity at Mayon during the week. Partial lava-dome collapses occurred on 11 June at 1347 and on 12 June at 1819. The 11 June collapse produced a small pyroclastic flow that descended the Bonga Gully, reaching an elevation of 1,480 m and producing a thin ash cloud that drifted to the E. The 12 June collapse sparked a period of vigorous, continuous emission of lava fragments for ~1 hour. During the week up to 198 rockfall events were detected per day. A maximum of 2,700 metric tons of SO2 was measured per day, which was lower than the previous week but above the baseline value of 500 tons/day. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone. PHIVOLC warned that residents around the volcano, especially those staying in areas facing the Bonga Gully and the SE sector, should be vigilant and prepared to evacuate at any time.

Sources: Philippine Institute of Volcanology and Seismology, Philstar.com

13-19 June 2001

A high level of high-frequency low-duration harmonic tremor was detected on Mayon that was associated with near-continuous detachment of hot rock fragments from the summit lava dome. In addition, moderate amounts of steam emanated from the crater, crater glow was fair-to-bright, and SO2 emission (average of ~2,700 metric tons per day) was well above the baseline value of 500 metric tons per day. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone.

Sources: Philippine Institute of Volcanology and Seismology

20-26 June 2001

A large, pyroclastic-flow producing eruption began at Mayon on 24 June at 1245. The first signs of heightened volcanic activity occurred on 19 June when tremor began that was associated with increased lava extrusion. SO2 emission increased to 6,000 metric tons on 19 June in comparison to an average of 1,700 metric tons per day the previous week. In addition, intense incandescence was observed at the dome and slight inflation was detected. By 23 June lava was rapidly flowing SE along the Bonga Gully towards the town of Mabinit, reaching 3.4 km from the volcano's summit. The same day at 1909 lava fountains rose at least 50 m above the summit crater rim. Due to the increase in activity PHIVOLCS raised the Alert Level to 4 (hazardous eruption possible within days).

On 24 June a series of strong explosions produced ash clouds that rose up to 1 km above the volcano and drifted to the N. At 1245 a pyroclastic flow descended about 4 km SE down the Bonga and Buyuan gullies, generating an ash cloud that ascended to 2.3 km. Beginning at 1644 explosions sent ash clouds to ~5 km above the summit crater. The largest eruption produced an ash cloud that rose to 10 km above the volcano. Ash generated from the pyroclastic flows and from the summit eruptions drifted to the NE towards the town of Malilipot. PHIVOLCS increased the Alert Level to 5 (hazardous eruption in progress) and the danger zone was extended from 7 to 8 km in radius. PHIVOLCS also announced that all areas within the declared danger zone should be immediately evacuated. The areas at greatest risk were near the Mabinit, Bonga, Matanag, and Buyuan gullies. After the large eruptions on 24 June a lull in activity occurred until at least 0630 on 26 June. This interval was marked by a decrease in seismic activity and only three small explosions. PHIVOLCS maintained Alert Level 5 due to the possibility of more explosive volcanic activity.

News agencies reported that ~25,000 residents near the volcano were evacuated on 24 June. Many returned to their homes the following day despite the evacuation order. There were no reports of injuries directly from the eruptions. On 25 June area airports were closed. News articles noted the possibility that rain from a tropical storm in the area could mix with ash and generate dangerous lahars. The provincial government declared a state of calamity in affected areas.

Sources: Philippine Institute of Volcanology and Seismology, Associated Press 6/25, Reuters 6/25, Reuters 6/26, Associated Press 6/26

27 June- 3 July 2001

After the large eruption on 24 June volcanic activity returned to relatively low levels for several days. During this period, rockfalls dominated the seismic records as lava slowly flowed to the SE down the Bonga Gully. PHIVOLCS reported that due to diminished lava extrusion lava was not expected to reach populated areas. Volcanic activity increased on 29 June when explosions occurred at 1605 and 1702. These explosions generated pyroclastic flows that traveled down the Bonga Gully and generated billowing ash clouds that ascended to ~4 km above the volcano. The pyroclastic flows reached ~3 km to the SE of the summit towards the general direction of Matanag Gully. During the eruption a portion of the Upper Basud Gully in the volcano's eastern sector collapsed. On 1 July, SO2 emission rates were as high as 8,700 metric tons per day, a value about 5-fold higher than on 29 June. By 2 June the rate of SO2 emission greatly decreased to 840 tons per day. PHIVOLCS stated that due to the ongoing significant inflation of the volcanic cone and anomalous rapid decline of SO2 emission rates a high likelihood of continued explosive eruptions in the coming days remains. Accordingly, the hazard status remained in the top category, Alert Level 5 (hazardous eruption in progress).

Sources: Philippine Institute of Volcanology and Seismology, Associated Press, Reuters

4-10 July 2001

A decrease in volcanic activity began on 3 July that led PHIVOLCS to reduce the Alert Level on 4 July from 5 (hazardous eruption in progress) to 4 (hazardous eruption imminent). In comparison to the previous week SO2 emissions decreased, seismic activity was lower, the rate of inflation of the volcano's edifice decreased, and there was no ash in the steam clouds that emanated from the crater. Alert Level 4 was maintained due to the possibility of minor ash puffs and secondary explosions caused by the contact of water with the voluminous hot lava. The extended danger zone was reduced from 8 km to 7 km in radius. On 4 July ~20,000 people who were evacuated from the most distal parts of the evacuation zone were permitted to return to their homes.

Sources: Philippine Institute of Volcanology and Seismology, Associated Press

11-17 July 2001

Volcanic activity continued to decrease at Mayon during 8-16 July, with low seismicity, occasional SE-directed rockfalls, and a general decrease in SO2 emission rates. Although the volcano's edifice remained slightly inflated, a gradual deflationary trend was detected. The activity decrease led PHIVOLCS to reduce the Alert level from 4 (hazardous eruption imminent) to 3 (increased tendency towards eruption). Authorities removed the 7-km-radius Extended Danger Zone in the SE, but left the 6-km-radius Permanent Danger Zone in effect on a long-term basis.

Source: Philippine Institute of Volcanology and Seismology

18-24 July 2001

Volcanic activity at Mayon was similar to the previous week. During 17-23 July seismicity consisted of four high-frequency and 37 low-frequency earthquakes, and 203 high-frequency short-duration harmonic tremors. An average of 4,100 metric tons per day of SO2 was emitted from the volcano, which was still above the baseline value of 500 metric tons per day. There was an overall deflationary trend and the intensity of incandescence observed at the crater ranged from barely visible to bright. Rockfalls occasionally rolled from the crater SE towards the Bonga Gully. The volcano remained at Alert Level 3 (on a scale of 0-5).

Source: Philippine Institute of Volcanology and Seismology

26 July 2001

Mayon began a new eruptive episode near midnight on 25 July when explosive activity fed pyroclastic flows for approximately 2 hours. By 0200 massive lava fountaining began and around 0300 residents within the 6 km radius permanent danger zone were evacuated. At 0756 on 26 July, approximately 4 hours after evacuations began, a large eruption produced an ash cloud that rose 10 km above the volcano and drifted to the SE. Pyroclastic flows traveled up to 5.5 km to the E and SE down the Bonga, Buyuan, and Basud gullies. Also, lava fountains rose up to 60 m above the volcano. Rain mixed with deposited ash, generating lahars that flowed along river channels. Later in the day eruptions occurred at 1420 and 1759. According to the Manila Bulletin, Ed Laguerta, resident volcanologist at PHIVOLCS said that the 0756 eruption was stronger and wider in magnitude than the series of eruptions on 24 June 2001.

By the evening of 26 July the 6 km radius danger zone had been increased to 8 km and approximately 40,000 people had been evacuated. Ash fell in the towns of Santo Domingo, Legazpi, Daranga, and Camalig in the Albay province. It is unusual for ash to fall in Daraga and Legazpi and the airport in Legazpi City was closed. Television reports stated that ash fell as far as the Sorsogon province, ~60 km S of the volcano. There were reports of ash deposits as much as 2.5 cm thick in some areas, but there were no immediate reports of injuries or damage. As of the evening of 26 July the volcano continued to release steam and ash accompanied by explosion-type earthquakes and harmonic tremor.
Sources: PHIVOLCS, Tokyo VAAC, Reuters, Associated Press, CNN, ABS-CBN, Manila Bulletin

25-31 July 2001

After the pyroclastic-flow producing eruptions on 26 July Mayon entered an effusive eruptive phase. During 27-31 July lava flowed up to 3.75 km toward the SE in the Bonga Gully, accompanied by numerous high-frequency short-duration tremor events caused by rock fragments detaching from the newly deposited lava flow. Incandescence was visible at the crater, and thick steam plumes and occasional short-lived ash emissions were seen. SO2 emission rates were high, with a maximum of 9,900 metric tons measured on 31 July, which was well above the baseline value of 500 metric tons/day. Due to the possibility of further explosions, Alert Level 5 (the highest level) remained in effect. According to news reports, on 31 July officials allowed residents who live outside of the 7-km danger zone to return to their homes.

Sources: Philippine Institute of Volcanology and Seismology, Associated Press, Reuters

1-7 August 2001

Volcanic activity during 1-4 August at Mayon consisted of high SO2 emission, high- and low-frequency harmonic tremor and low-frequency volcanic earthquakes, slight inflation of the edifice, and the ejection of lava fragments up to 100 m above the crater rim. PHIVOLCS stated that activity had decreased since the 26 July eruptions and the volcano was in a mild state of eruption. According to news reports, approximately 26,500 people were still evacuated from their homes near the volcano. Mayon remained at Alert level 5, the highest level.

Sources: Philippine Institute of Volcanology and Seismology, Manila Bulletin, Associated Press

8-14 August 2001

A decline in seismic and volcanic activity occurred at Mayon beginning on 8 August. The level of seismicity remained above background, but declined to non-eruptive conditions. The volcano's edifice was less inflated than during previous weeks. Continuing low-level activity in the crater area produced a high SO2 emission rate and visible incandescence. On 9 August PHIVOLCS decreased the Alert Level from 5 (the highest) to 4. The 6-km-radius Permanent Danger Zone and the 7-km-radius Extended Danger Zone remained in effect.

Sources: Philippine Institute of Volcanology and Seismology, Inquirer News Service

15-21 August 2001

Volcanic activity remained relatively low at Mayon during the week. Few rockfalls were observed, seismicity was relatively low, incandescence was not visible in the crater, and no inflation was detected at the volcano's summit. SO2 emission rates reflected continuous degassing of residual magma. Because volcanic and seismic activity had been declining for the previous 2 weeks, on 21 August PHIVOLCS decreased the Alert Level at the volcano from 4 (hazardous eruption imminent) to 3 (increased tendency towards eruption). As a consequence, the Extended Danger Zone (EDZ) in the SE returned to the original 6-kilometer radius Permanent Danger Zone (PDZ).

Source: Philippine Institute of Volcanology and Seismology

22-28 August 2001

Volcanic activity remained low at Mayon during 22-28 August. There was relatively little seismic activity, slight inflation, occasional observations of incandescence at the summit, and a moderate amount of steam emitted from the volcano. SO2 emission rates remained well above the baseline value of 500 metric tons per day. PHIVOLCS reminded residents along the banks of major channels that lahars and torrential stream flows during heavy rains could remobilize material from pyroclastic-flow deposits. The volcano remained at Alert Level 3.

Source: Philippine Institute of Volcanology and Seismology

29 August- 4 September 2001

During the week seismicity was relatively low, SO2 emission rates were well above the baseline value of 500 metric tons per day, the edifice was slightly inflated, and steaming and incandescence were occasionally visible at the crater. The volcano remained at Alert Level 3.

Source: Philippine Institute of Volcanology and Seismology

21-27 November 2001

News reports on 21 November stated that lahars were generated at Mayon after several days of heavy rainfall mixed with unconsolidated material on the volcano's slopes. According to the civil defense, flooding caused more than 4,800 families to be evacuated from their homes.

Source: Philippine Institute of Volcanology and Seismology

6-12 February 2002

A continuous decline in volcanic activity has occurred at Mayon since the volcano's Alert Level was reduced from 2 to 1 on 19 October 2001. On 5 February PHIVOLCS further decreased the Alert Level to 0 because all measured parameters had decreased. Incandescence, probably from still-hot residual magma beneath the crater, remained visible at the summit.

Source: Philippine Institute of Volcanology and Seismology

30 October-5 November 2002

According to news articles, the Alert Level at Mayon was raised from 0 to 1 (on a scale of 0-5) after increased seismicity and gas emission were recorded. The amount of SO2 emitted increased from ~950 tons/per day during the previous week, to ~2,670 tons on 29 October. Residents near the volcano were notified that they must not enter the 6-km radius Permanent Danger Zone, especially on the SE side of the volcano.

Sources: Associated Press, ABS-CBN

12-18 March 2003

PHIVOLCS raised the Alert Level at Mayon from 0 to 1 (on a scale of 0-5) after an explosion occurred on 17 March at 1819. The brief burst of ash and steam rose to ~1 km above the summit and drifted WNW. Prior to the explosion no significant seismicity was recorded. During 0900-1100 SO2 emission rates were higher than normal at 890 tons per day (500 tons are normally measured during repose), and electronic tiltmeters on the volcano's N and S flanks indicated a slight inflation of the edifice beginning on 13 March. PHIVOLCS emphasized that the 6-km-radius Permanent Danger Zone was in effect.

Sources: Philippine Institute of Volcanology and Seismology, Associated Press

7-13 May 2003

On 6 May at 0721 a small explosion occurred at Mayon. The brownish ash-and-steam column produced from the explosion rose about 450 m above Mayon's summit crater and drifted SW. No significant seismicity was recorded prior to the explosion. Electronic tiltmeters on the N and S flanks continued to show inflation of the volcanic edifice. Likewise, a leveling survey conducted on 24 April showed a general inflation of the N flank. Mayon remained at Alert Level 1 (on a scale of 0-5). PHIVOLCS emphasized that the 6-km-radius Permanent Danger Zone remained in effect.

Sources: Philippine Institute of Volcanology and Seismology

14-20 May 2003

On 14 May at 1813 a small and brief explosion at Mayon's summit crater produced a small NW-drifting ash puff that rose less than 100 m above the crater. Two seismic stations recorded this as a small-amplitude event. PHIVOLCS stated that there had been a succession of minor emissions in the past few months and that ongoing unrest may lead to more vigorous activity. The Alert Level remained at 1 (on a scale of 0-5), but PHIVOLCS indicated it would consider increasing the Alert Level if the current pace of unrest is sustained.

Source: Philippine Institute of Volcanology and Seismology

17-23 September 2003

During 14 August to 18 September, seismicity at Mayon remained within background levels (less than five earthquakes/day). No volcanic earthquakes were recorded after 14 September. Moderate volcanic-gas emissions were observed during most of the report period. The sulfur-dioxide flux remained above baseline repose levels. Mayon remained at Alert Level 1 (on a scale of 0-5), with a 6-km-radius Permanent Danger Zone.

Source: Philippine Institute of Volcanology and Seismology

8-14 October 2003

PHIVOLCS raised the Alert Level at Mayon from 1 to 2 (on a scale of 0-5) on 11 October after incandescence was seen in the E portion of the volcano's crater, sulfur-dioxide emission rates increased from ~1,600 tons on 1 October to ~2,380 tons on 9 October, and the number of volcanic earthquakes had been increasing slightly for several weeks. PHIVOLCS believes that slow magma intrusion may be occurring. The 6-km-radius Permanent Danger Zone remained in effect.

Source: Philippine Institute of Volcanology and Seismology

15-21 October 2003

According to news reports, the continuing unrest at Mayon led authorities to extend the 6-km-radius Permanent Danger Zone to 7 km in the SE quadrant of the volcano on 13 October. Seismicity and SO2 emissions increased during the previous week. During a 24-hour-monitoring period, ending the night of 17 October, 16 volcanic earthquakes were recorded beneath Mayon's lower flanks. Authorities maintained Alert Level 2 (on a scale of 0-5).

Source: The Manila Bulletin

12-18 May 2004

According to a news article, PHIVOLCS reported that three volcanic earthquakes were recorded at Mayon during the week of 9 May, suggesting a renewed period of unrest. In addition, incandescence was visible in the crater and moderate steaming was seen. On 12 May, the sulfur-dioxide flux increased from the normal level of ~500 tons per day to ~1,170 tons. People were reminded not to enter the 6-km-diameter Permanent Danger Zone around Mayon.

Source: ABS-CBN News

21-27 July 2004

According to a news article, during the week of 18 July emissions from Mayon deposited ash on two villages near the volcano. Reportedly, a PHIVOLCS scientist stated that the explosions may have occurred due to water contacting hot rocks.

Source: Associated Press

8-14 September 2004

On 12 September, faint glow was visible at Mayon's summit that coincided with a slight increase in overall background tremor. According to PHIVOLCS, these observations indicated a possible renewed episode of volcanic unrest, probably due to small incremental intrusions of magma at shallow depths that caused the intensified glow at the summit. They reported that small explosions, similar to the events on 3 June and 22 July 2004, may be expected as pockets of gas beneath the crater are suddenly released. There were no significant changes in ground deformation or sulfur-dioxide flux. According to a news report, volcanic material was emitted from Mayon late on 12 September, setting fire to grass on the volcano's slopes. People were reminded to remain outside of the 6-km Permanent Danger Zone. Mayon was at Alert Level 2 (on a scale of 0-5).

Source: ABS-CBN News

13-19 October 2004

According to a news report, seismicity increased at Mayon during 18-19 October. Based on information from PHIVOLCS, the article reported that seven low-frequency earthquakes and harmonic tremor were recorded in a 24-hour period.

Source: ABS-CBN News

1-7 December 2004

According to a news report, strong rains brought by typhoon Yoyong in the Philippines caused lahars to flow down the stream channels of Mayon, particularly in the Padang settlement, and Legazpi City (~14 km SE of the volcano's summit). The Provincial Disaster Management Officer stated that the lahars would not cause damage to homes or rice fields, and that villagers residing near the volcano were not asked to evacuate.

Source: ABS-CBN News

24-30 August 2005

PHIVOLCS reported on 23 August that an aerial survey of Mayon conducted on 17 August revealed that lava had accumulated within the volcano's summit crater. The lava dome was extruding very slowly and the volume of lava was contained within the crater. PHIVOLCS warned that the volcano remains at Alert Level 2, and that people cannot enter the Permanent Danger Zone of 6 km radius around the volcano.

Source: Philippine Institute of Volcanology and Seismology

15-21 February 2006

A minor explosion at Mayon on 21 February at 0941 produced an ash plume that rose to ~500 m above the volcano's crater (or 9,700 ft a.s.l.) and drifted SW. Ash was deposited on the upper slopes of the volcano. The ash emission was accompanied by a small explosion-type earthquake, recorded only by seismographs around the volcano.

Prior to the explosion, an increase in seismicity was recorded at the volcano. Between 1545 on 20 February and 0520 on 21 February, there were 147 low-frequency volcanic earthquakes recorded, considerably above the five or fewer events per day that are normally recorded. Some minor rockfalls were indicated and probably resulted from detachment of lava blocks from the summit. Steaming was observed. No incandescence was visible at the crater due to clouds obscuring the volcano. Mayon remained at Alert Level 2, with a 6-km-radius Permanent Danger Zone in effect. PHIVOLCS expects similar ash explosions in the coming days as magma intrudes the summit area and releases volcanic gases.

Source: Philippine Institute of Volcanology and Seismology

22-28 February

PHIVOLCS reported that about nine earthquakes related to explosive activity took place at Mayon around 23 February. Cloudy conditions prevented observations of the volcano, but seismic events probably accompanied minor ash explosions. This was supported by reports from residents near the volcano who heard rumbling. The seismic network also recorded two low-frequency volcanic earthquakes associated with shallow magma movement. The sulfur-dioxide flux averaged 1,740 metric tons per day (t/d), similar to values obtained during the last measurement on 28 November 2005. The flux was well above the usual 500 t/d measured at the volcano. Mayon remained at Alert Level 2, with a 6-km-radius Permanent Danger Zone in effect.

Source: Philippine Institute of Volcanology and Seismology

12-18 July

Phreatic eruptions at Mayon on 13 July produced ash that fell up to approximately 5.3 km NE in Calbayog, Malilipot. The Alert Level was raised from 1 to 3 (scale is 0-5, 0 referring to No Alert status) after observers reported lava flows on the SE slopes, the predominant direction for lava flows and rockfalls. On 16 July, a danger zone 6 km from the summit was extended to 7 km in the SE area. Incandescent material was shed from an 800 m long lava flow moving SSE towards Bonga gully on 16 and 17 July. On 18 July, PHIVOLCS reported that the lava flow reached 1 km in length and incandescent boulders rolled 3 km towards the Bonga gully.

Sources:Philippine Institute of Volcanology and Seismology, Manila Standard Today, Associated Press, Associated Press/Sunnex

19-25 July

PHIVOLCS reported that during 19-24 July lava flows from Mayon traveled SSE a maximum distance of 4 km from the summit toward the Bonga gully and branched off to the W and E. Incandescent blocks shed from the toe and margins of the flows were visible at night and traveled SE. Ash plumes generated from the rolling blocks produced light ash fall 8.5 km E of the summit in Sta. Misericordia. On 20 July, pyroclastic flows were observed on the SE slopes prompting ~100 families to evacuate. On 22 July, lava flows advanced NE towards the Mabinit channel. The lava flows were within the 6 km radius Permanent Danger Zone.

Sources:Philippine Institute of Volcanology and Seismology, Jun P. Yap and Agence France-Presse, Gulf News

26 July to 1 August 2006

Lava flows from Mayon in the SE sector of the Bonga gully advanced ~1.35 km during 26 July-1 August to reach a maximum distance of 5.8 km SSE from the summit on 1 August. Smaller lava flows and incandescent blocks descended adjacent gullies. On July 29, light ash accumulation was reported about 12 km S and SE, in Daraga municipality and Legazpi City and vicinity, respectively. Emissions of sulfur-dioxide reached ~12,500 tons per day on 31 July, a record high for the current period of unrest.

Source:Philippine Institute of Volcanology and Seismology