SIGNS OF VOLCANO ERUPTION

• Ground Deformation

  may be detected only by sensitive instruments. An

  increase in the frequency and intensity of

  felt earthquakes.
• An Electronic Distance Meter (EDM)

  measures accurately millimeter changes on

  the ground (if the slope of the volcano

  swells).
• An electromagnetic distance

  measuring instrument is a surveying

  instrument for measuring the distance

  between two points through

  electromagnetic waves.
• GEOCHEMISTRY Gas emission from volcanoes. Changes in

  the composition or relative abundances of

  fumarolic gases (SO2).
• GEOCHEMISTRY Noticeable steaming or fumarolic activity

  and new or enlarged areas of hot ground.

  Observe changes in temperature as water

  becomes more acidic.
• GEOCHEMISTRY

  Correlation Spectrometer (COSPEC) is used

  to measure the amount of sulfur dioxide in

  a passing air mass (or volcanic plume).
• SEISMIC ACTIVITY observes an increase in several volcanic

  earthquake records. Seismometer is the

  equipment used to detect occurrences of

  volcanic earthquakes.
• REMOTE SENSING Monitoring surface changes on

  a volcano from afar using available tools

  such as satellite images.
• REMOTE SENSING Advantages: less exposure on the ground

  for volcanologists, safer; but sometimes

  interpretation needs field verification.
• Sensory Observations

  a.Intensifies steaming activity

  b. What used to be white steam slowly or drastically changed from gray to dark

  (suggests the increasing presence of ash).
• Sensory OBSERVATIONS

  c. Drying up of vegetation, drying up of

  streams, and water wells.

  d. Crater flow at the summit area
• Sensory OBSERVATIONS

  e. Increasing frequency of rolling rocks

  from the summit; localized landslides

  not related to heavy rains

  f. The summit area appears to glow or

  becomes incandescent at night
• Sensory OBSERVATIONS

  g. Hear rumbling sound

  h. The smell of sulfur (rotten eggs)

  i. Ground movement/volcanic

  earthquakes increasingly become felt
• ALERT LEVEL SYSTEM OF PHIVOLCS

  ● Alert Level 0 (No Alert)

  ○ Quiet

  ○ No eruption in the foreseeable future

  ● Alert Level 1 (Abnormal)

  ○ Low-level unrest

  ○ No eruption imminent
• ALERT LEVEL SYSTEM OF PHIVOLCS

  Alert Level 2 (Increasing Unrest)

  ○ Moderate unrest

  ○ Unrest probably of magmatic origin, could

  eventually lead to eruption

  ● Alert Level 3 (Increasing Tendency Towards Eruption)

  ○ Relatively high unrest

  ○ Margma is close to the crater
• ALERT LEVEL SYSTEM OF PHIVOLCS

  Alert Level 4 (Hazardous Eruption Imminent)

  ○ Intense unrest

  ○ Hazardous eruption is possible within days

  ● Alert Level 5 (Hazardous Eruption)

  ○ Hazardous eruption