ALERT

CRITERIA

INTERPRETATION/RECOMMENDATION

No Alert/Alert Level Zero (NORMAL)

Background level, no unusual activity

Volcanic activity is at its background level.

No eruption is indicated. However, there are associated risks when venturing within the Permanent Danger Zone (PDZ), defined as a circular area with the crater at the center and swept by a radius of Four (4) kilometers. The volcanic hazards associated with these risks could include steam bursts or ash ejections which may occur suddenly and without perceptible precursors or warning.

1

Slight Unrest

Slightly elevated levels of seismic, fumarolic and/or other volcanic activity. Isolated steam bursts or ash ejections.

May lead to more steam and ash ejections which affect the crater and summit area only. The source of activity is shallow, near crater. No magmatic activity is indicated. No entry within the Four (4) kilometer radius PDZ.

2

Elevated Level of Volcanic Unrest

Elevated levels of any of the following: seismic, fumarolic and/or other volcanic activity. Repeated ash ejections.

Probable ascent and intrusion of magma. Events could lead to hazardous eruption. No entry within the Four (4) kilometer radius PDZ.

3

High Level of Volcanic Unrest

Seismic swarms, tremor and high level of other monitored parameters. More energetic and more frequent steam/ash ejection.

Magmatic processes underway. Events could lead to hazardous eruption. Danger Zone extended to at least Six (6) kilometer radius from the active crater.

4

Eruption Imminent

Intense unrest which may be characterized by frequent periods of high frequency volcanic quakes, tremors, some felt; vigorous steam/gas discharge from crater. Summit incandescence, lava dome.

Gas-charged magma is close to or at crater surface. Hazardous eruption is likely, possibly within hours or days.

Danger Zone extended to Ten (10) kilometers radius.

5

Alert Level 5 (Life-Threatening ERUPTION)

Hazardous eruption in progress with billowing tall ash-laden eruption clouds and/or pyroclastic flows/lava flows. Lahars.

Hazardous eruption in progress. Flowing or falling materials encroach into settlements.

If there is reason to believe that explosive eruption shall intensify, the Danger Zone may be extended to 14 kilometers.