RHUM-RUM
is
a
German-French
seismological
experiment
based
on
the
sea
floor
surrounding
the
island
of
La
Réunion,
western
Indian
Ocean.
Its
primary
objective
is
to
clarify
the
presence
or
absence
of
a
mantle
plume
beneath
the
Reunion
hotspot.
RHUM-RUM's
central
component
is
a
13-month
deployment
(Oct
2012
to
Nov
2013)
of
57
broadband
ocean
bottom
seismometers
(OBS)
and
hydrophones
over
an
area
of
2000x2000
km2
surrounding
the
hotspot.
The
array
contained
48
broadband
OBS
from
the
German
DEPAS
pool
and
9
stations
from
the
French
INSU
pool.
It
has
been
the
largest
deployment
of
DEPAS
and
INSU
OBS
so
far,
and
the
first
large
joint
experiment.
We
give
an
overview
of
station
performance
and
issues
encountered,
touching
on
instrument
responses,
recorder
and
battery
performance,
noise
characteristics,
and
data
yield.
Of
the
57
stations,
46
had
proper
seismometer
and
53
proper
hydrophone
recordings.
Out
of
a
installation
time
of
13x57=741
station-months,
412
months
of
data
were
actually
realized
for
the
seismometers,
and
710
for
the
hydrophones.
At
long
periods
(>10
s),
the
DEPAS
stations
are
affected
by
significantly
more
noise
than
the
INSU
stations,
a
difference
that
is
most
pronounced
on
the
horizontal
components
and
can
probably
be
explained
by
tilting
of
the
instrument
assemblage.
The
DEPAS
sensors
are
integrated
into
the
OBS
frame
and
buoy
assemblage,
and
would
therefore
record
its
motions,
caused
for
example
by
the
action
of
deep
sea
currents.
However,
this
integrated
setup
also
makes
the
DEPAS
OBS
easier
to
deploy
and
recover,
especially
in
large
deployments
such
as
this
one