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Report on Mayon (Philippines) — August 2006

Bulletin of the Global Volcanism Network, vol. 31, no. 8 (August 2006)
Managing Editor: Richard Wunderman.

Mayon (Philippines) Lava extruding but with less vigor

Please cite this report as:

Global Volcanism Program, 2006. Report on Mayon (Philippines). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 31:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200608-273030.

Volcano Profile |  Complete Bulletin


Mayon

Philippines

13.257°N, 123.685°E; summit elev. 2462 m

All times are local (unless otherwise noted)


During 6 September to 3 October 2006, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) described lava extrusion and associated rockfalls on Mayon's SE slopes. This continued the previous pattern seen during 23 August-5 September 2006 (BGVN 31:07). Mayon's eruptive vigor generally declined by mid-September into October. Background on Mayon's geography follows (figures 13-15 and table 9).

Figure (see Caption) Figure 13. Satellite image of the SE area of the Philippine island of Luzon showing Mayon volcano and surrounding volcanoes and towns. Courtesy of Google Earth.
Figure (see Caption) Figure 14. Oblique aerial image of Mayon, looking from the N at an eye altitude of 1.78 km. Courtesy of Google Earth.
Figure (see Caption) Figure 15. Contour map of Mayon volcano showing surrounding towns (see table 9 for more detailed list of names of nearby settlements) . The prominent circle around the volcano delineates the 6-km Permanent Danger Zone. Scale is 1:50,000. Courtesy of PHIVOLCS.

Table 9. An alphabetical list including some of the settlements and other place names on and surrounding Mayon volcano, and their bearings and distances from the summit. Taken from the PHIVOLCS map referenced below.

Town Name Bearing Distance (km)
Alcala SSE 9.6
Amtic NW 7.7
Anoling SSW 6.1
Arimbay SE 10.9
Bacacay ENE 12
Baligang WNW 6.2
Banadero S 8
Bantayan NNW 9.5
Baranghawon NNE 11.4
Basag W 9.6
Basagan N 8.8
Bigaa ESE 10.1
Binanowan W 10.7
Binitayan NE 10.5
Binogsacan SW 12.5
Bonga SE 8.5
Bongabong NNE 9.3
Bono? NNW 7.8
Boring N 8.2
Buang NW 7.4
Bubulusan WSW 10.3
Budiao S 8.1
Buhian NNW 8.3
Burabod SE 9.9
Buyuan SE 8.1
Cabangan SSW 8.1
Cagsawa S 10
Calbayog NE 6.5
Camalig S 8.8
Canaway NNE 7.6
Comon N 6.8
Daraga SSE 12.2
Dita SE 10.3
Dona Tomasa WSW 8.5
Fidel Surtida E 9.9
Guinobat N 11
Guinobatan SW 11.8
Hindi NE 10.4
Ilawod SW 11.5
Kilicao SSE 10.3
Legaspi City SSE 13.5
Libod SSW 10
Lidong ESE 8.7
Ligao W 14
Lower Bonga ENE 8.1
Mabinet SSE 8.5
Magapo NW 5.7
Maipon SW 10
Malilipot NE 9
Maninila SW 8.1
Mariroc N 9.7
Masarawag SW 8.1
Matagbac N 11
Matanag SE 8.4
Matnog SSE 8.4
Mayon Rest House Observatory NW 3.6
Miisi S 6
Muladbucad Grande W 8.9
Muladbucad Pequeno W 8.8
Nabonton W 10.3
Nasisi W 10.8
Oson N 7.3
Padang ESE 9.4
Pingabobong N 8.3
Quinastillohan N 10
Quirangay SSW 7.3
Rawis SSE 11.7
Sabinitayan NE 10.5
Salugan SSW 7.8
Salvacion S 8.6
San Andres E 10.4
San Antonio N 10.2
San Fernando E 8.2
San Francisco NE 8.8
San Isidro NNE 9.3
San Joaquin SE 11
San Lorenzo NNE 11.7
San Rafael SW 10.8
San Roque E 8.8
San Vincente N 11.4
Sta. Misericordia E 8.2
Sta. Misericordia Observatory E 7.9
Sta. Cruz NNE 8.7
Sto. Domingo ESE 10
Sua SSW 8.1
Sugod NE 10.6
Tabaco NNE 12.5
Tabiguian NW 8.8
Tagas NNE 11.2
Tambo WNW 7.9
Tandarora SW 9.4
Travesia SW 10.8
Tumpa SW 8
Upper Bongo ENE 8.3

Seismicity and lava extrusion generally decreased during 6-26 September. SO2 fluxes broadly declined, generally ranging between 1,200 and 3,000 tons per day, although the 25 August and 2 September readings were outliers, ~ 5,400 and ~ 6,600 tons per day, respectively. Ground-deformation measurements showed an overall deflation. On 11 September, the Alert Level was lowered from 4 to 3 (on a scale of 0-5, with 0 referring to No Alert status).

During late September surface activity was characterized by intermittent spalling of incandescent lava fragments and glow from the summit crater. Steaming at the summit was moderate with white plumes drifting NNE and SE. Low-frequency tremor continued to indicate elevated unrest. Alert Level 3 remained in effect, meaning that the new Extended Danger Zone (EDZ) of 7 km from the summit crater in the SE sector and the normal 6 km-radius Permanent Danger Zone (PDZ) for other areas continued. Table 10 lists Mayon's reported seismicity from 25 August-27 September 2006, continuing the list developed in BGVN 31:07.

Table 10. Summary of 25 August-3 October 2006 events observed at Mayon volcano for 24-hour periods ending at 0800 hours on the date indicated. The SO2 emission rates apply to the gas within the volcanic plume. No data was available for 10, 28, or 29 September. Courtesy of PHIVOLCS.

Date Volcanic Earthquakes Tremor Episodes Low-frequency Harmonic Tremor SO2 Emission Rate (tons/day) Comments
25 Aug 2006 17 303 -- 5401 (magma degassing) Mild state of eruption, Alert Level 4.
01 Sep 2006 25 277 -- -- Lava extrusion, four explosions.
02 Sep 2006 31 248p -- 6585 (high) Small explosion.
03 Sep 2006 9 high -- 2021 --
04 Sep 2006 -- 305 -- 2961 --
05 Sep 2006 0 455 -- 1447 --
06 Sep 2006 13 295 -- 2032 --
07 Sep 2006 10 315 -- -- --
08 Sep 2006 26 333 -- 1841 --
09 Sep 2006 2 300 -- 1701 --
11 Sep 2006 6 206 -- 1500 --
12 Sep 2006 0 253 -- 1500 Begin Alert Level 3.
13 Sep 2006 8 108 -- 1500 --
14 Sep 2006 18 111 -- 1500 --
15 Sep 2006 12 104 continuous 1600 --
16 Sep 2006 2 31 continuous 1400 --
17 Sep 2006 -- 57 -- 1800 --
18 Sep 2006 2 57 continuous 1500 --
19 Sep 2006 -- 47 -- 1500 --
20 Sep 2006 1 33 continuous 1200 --
21 Sep 2006 3 20 continuous 2200 --
22 Sep 2006 2 80 continuous 1600 Lava extrusion.
23 Sep 2006 1 14 continuous 1599 Decline in lava extrusion.
24 Sep 2006 6 21 continuous -- Intense crater glow.
25 Sep 2006 14 114 -- 1300 Crater glow, lava extrusion.
26 Sep 2006 12 65 -- 1200 --
27 Sep 2006 7 18 -- None measured due to rain. Crater glow, lava fragments.
30 Sep 2006 0 3 -- None measured due to weather. White plumes drifting ENE.
01 Oct 2006 0 0 -- None measured due to weather. White plumes drifting ENE.
02 Oct 2006 0 0 -- None measured due to weather. --
03 Oct 2006 0 0 -- -- --

Reference. PHIVOLCS, (date unknown), Geologic map of the deposits and features of the 1984 eruption of Mayon Volcano: PHIVOLCS, prepared by H.B. Ruelo, scale 1:50,000.

Geologic Background. Beautifully symmetrical Mayon, which rises above the Albay Gulf NW of Legazpi City, is the Philippines' most active volcano. The structurally simple edifice has steep upper slopes averaging 35-40 degrees that are capped by a small summit crater. Historical eruptions date back to 1616 and range from Strombolian to basaltic Plinian, with cyclical activity beginning with basaltic eruptions, followed by longer term andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. A violent eruption in 1814 killed more than 1,200 people and devastated several towns.

Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/).