Publication Date:
2017-04-04
Description:
Measurement of effusion rate is a primary
objective for studies that model lava flow and magma
system dynamics, as well as for monitoring efforts during
on-going eruptions. However, its exact definition remains a
source of confusion, and problems occur when comparing
volume flux values that are averaged over different time
periods or spatial scales, or measured using different
approaches. Thus our aims are to: (1) define effusion rate
terminology; and (2) assess the various measurement
methods and their results. We first distinguish between
instantaneous effusion rate, and time-averaged discharge
rate. Eruption rate is next defined as the total volume of
lava emplaced since the beginning of the eruption divided
by the time since the eruption began. The ultimate
extension of this is mean output rate, this being the final
volume of erupted lava divided by total eruption duration.
Whether these values are total values, i.e. the flux feeding
all flow units across the entire flow field, or local, i.e. the
flux feeding a single active unit within a flow field across
which many units are active, also needs to be specified. No
approach is without its problems, and all can have large
error (up to ∼50%). However, good agreement between
diverse approaches shows that reliable estimates can be
made if each approach is applied carefully and takes into
account the caveats we detail here. There are three
important factors to consider and state when measuring,
giving or using an effusion rate. First, the time-period over
which the value was averaged; second, whether the
measurement applies to the entire active flow field, or a
single lava flow within that field; and third, the measurement
technique and its accompanying assumptions.
Description:
Published
Description:
1-22
Description:
1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
Description:
JCR Journal
Description:
reserved
Keywords:
Lava
;
Instantaneous effusion rate
;
Time-averaged discharge rate
;
Eruption rate
;
Monitoring
;
04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
;
04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
;
04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
