felt shocks
-
frequency per day
-
months or days before eruption
-
maximum intensity I to XII
-
distance from vent
|
unfelt shocks
-
frequency per day
-
S-P duration/ sec
-
max ground amplitude (um or um/s at ...
km from vent)
|
micro-tremors
-
duration (total days or hours)
-
period (sec)
-
max amplitude (um or um/s at ... km from
vent)
|
increase in ground temperature
-
area affected (sq km)
-
distance from eruption point
-
max temp (C)
-
increase temp from normal
-
time before eruption
|
Changes in gas emission
-
none, moderate, significant
|
| ground changes
|
tilt
-
outwards, inwards, none
-
amount (u radian)
-
distance from vent
-
time before eruption
|
magnetic changes
-
amount (gamma, or sec of arc)
-
time before eruption
|
| other precursary phenomena |
