On Sat, Aug 31, 2024 at 12:35 AM Ulrich Speidel via Starlink <starlink@lists.bufferbloat.net> wrote:

Howdy all,

There were quite a few folk on this list a couple of years back who were
interested in what was happening to Internet in Tonga after the big
volcanic eruption there. I'm not sure where I left off.

To re-cap, Tonga lost about 90 km of its international connection to
Fiji at the time (a few dozen km of that could be recovered), and an
amount of cable of similar magnitude on the Tonga Domestic Cable
Extension (TDCE) that ran a fibre pair each to both Vava'u and Ha'apai
from the main island Tongatapu. The TDCE is one of the longer
unrepeatered stretches of submarine cable in the world and runs in a
submarine trench just downhill from the Hunga Tonga Hunga Ha'apai
volcano and its siblings in the chain. Simulations at the timed showed
that this trench likely received a large amount of the material that was
ejected from the volcano, likely several cubic kilometres, and acted as
a kind of gutter that guided the material away from the volcano in
turbidity flows stretching over hundreds of km. At the time, the cable
ship sent to repair was unable to repair the TDCE for lack of spare
cable - nothing was recoverable from the seafloor, and there was not
enough spare cable in the South Pacific to bridge the gap.

Spare cable was ordered from France and was installed middle of 2023,
restoring the TDCE to service.

Then, on 29 June 2024, an earthquake near the volcanoes caused yet more
debris to descend on the cable, obliterating 13.7 km of it and cutting
service to both Vava'u and Ha'apai again. Cable ship MV Lodbrog was
brought in from Singapore with 60 km of spares but got delayed in Fiji
due to mechanical issues. The cable was repaired on 16 August 2024, in
the same location. The operators were well aware of the risk, however
re-routing the cable would have required it to be lengthened, with the
need to insert repeaters, upgrade terminal equipment, and conduct a new
marine survey, which would have meant further delays.

On 26 August 2024, 11:29 am, a M6.9 quake struck in the area at a depth
of about 106 km. Our Science building in Auckland has a "citizen
science" seismograph with a big display in its foyer, and my student and
I noticed the very prominent event as we returned from lunch. Little did
we know that this wasn't as close to home as we'd thought, but would
touch us in other ways that week. You've guessed it: The cable has been
cut again, the cable ship's been recalled, and nobody quite knows what
they'll find this time.

https://matangitonga.to/2024/08/27/domestic-submarine-cable-out-again-after-haapai-earthquake-yesterday

The latest plan I know of was to repair in the same location again,
using armored spares - but they know that this may not prevent further
damage. Geological advice is that any decent quake in the area will
cause further submarine landslides in the coming years until the area
has settled.

Meanwhile, Starlink has been licensed to operate commercially in Tonga.
For many Pacific Island countries, this is a double-edged sword: On the
one hand, this provides short-term relief, on the other hand, it
deprives local ISPs of customers and therefore impacts on aspirations to
achieve cable connectivity which could provide more bandwidth in the
medium term.

Some island nations have not yet licensed Starlink, but allow Starlink
units on regional roaming plans to operate there. In some cases, there
are now hundreds of such units operating in individual cells. This
appears to be causing Starlink some headaches in terms of capacity -
we've seen them being creative when it comes to user density management
before. What happens if Starlink are going to be licensed there but
can't offer fixed service on the ground because of the large number of
roaming subscribers already there? I understand that some of these
"roaming" users have been contacted by Starlink with a request to either
take these units back to their home location country where they are
registered (which isn't likely to happen given the cost involved) or
register them in the country they're currently in (not possible in some
cases for lack of local fixed service offered).

Ulrich

--
****************************************************************
Dr. Ulrich Speidel

School of Computer Science

Room 303S.594 (City Campus)

The University of Auckland
u.speidel@auckland.ac.nz
http://www.cs.auckland.ac.nz/~ulrich/
****************************************************************

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