Hollow Moon Planetology: Blue Moon - Natural Disasters
by Sharon Dornhoff Lunar Volcanoes and "Fire
Times"
Just as the effects of Pateran gravity upon the Hollow Moon's
atmosphere are predictable, so are its effects upon the geological
activity beneath the surface of Nearside land masses*. Patera's
tidal pull keeps magma beneath the surface of "hot spots" in a
dynamic, fluid state, counterbalancing the crystalbarrens' chilling
effect upon the lower atmosphere and keeping Matera's interior from
freezing. This effect is especially strong on eight separate
occasions during the 18-month lunar "year", when Patera passes
within 5 degrees or less of the visible moon, and Seshay-Selene
manipulates its gravity to influence the elements of earth and
fire, rather than air and water. These events, called "Fire Times"
by Materans, can be highly destructive; yet, they are also
predictable to within an incredible 3-hour interval (!), and are
tracked over time as a part of the Storm Cycle which all
inhabitants of the Hollow Moon plan out their lives in accordance
with. Two of the annual Fire Times are quite mild, two can be
devastating to large areas of the Nearside, and the remainder fall
somewhere in-between. Barring a lunar total eclipse, volcanic
eruptions in the HM setting will occur at these times and no
others; so often do lunar volcanoes get to release their fury, on a
set schedule, that there's no time for such an "out-of-season"
eruption to build up.
[* - Crystalbarrens, including those covered by seas, aren't
subject to this effect. With the exception of the unusually-large
Fra Mauro Islands in the Midland Ocean, none of the crystalbarrens'
volcano-islands are active in the present era ... unless, of
course, the DM chooses to make them so.]
Not all volcanoes in the HM setting erupt, in every Fire Time, of
course: that'd be overkill! Rather, individual active volcanoes are
assigned a rating by the DM of One, Two, or Three. Rating One
volcanoes will erupt only during a severe Fire Time; rating Two,
under severe or moderate Fire Times; and rating Three (the most
active) during any Fire Time on the Materan calendar. In addition
to these, "semi-active" volcanoes will erupt only once every few
years, always during a severe Fire Time; these may be assigned a
die of the DM's choice -- anything from a d4 to a d100 -- to
determine the number of lunar years between eruptions. Naturally, a
semi-active volcano can erupt in any year the DM desires that it do
so ... but even then, such cones should blow only during severe
Fire Times. "Dormant" volcanoes haven't erupted in living memory --
which is several centuries, given the lifespans of vesper elves,
gnomes, and Modrigswerg -- and are, if not geologically "dead", at
least safe to live upon in the opinion of native Materans. Only the
volcanoes of the crystalbarrens, and (we hope! :-D) the awesome
Mount Copernicus on the Midland Ocean's western shore are truly
extinct, in the Hollow Moon.
Nor are all of Matera's volcanic eruptions created equal, among
those which DO occur in a given Fire Time. The Apennines, although
their peaks rate a Three for activity, seldom expel anything but
steam and occasional rains of hot pebbles from their vents.
Taruntius on the Foecunditatis/Tranquillitatis Strait is infamous
for its fumaroles, that vomit forth clouds of toxic hydrogen
sulphide gas to drift over the nearby waters. Gutenberg's
lava-flows follow the same path southward, year after year,
building up a long ridge that reaches much of the way to Mare
Nectaris while seldom endangering any lives. The very young volcano
known ruefully as Hell* popped up out of a beet field in Deslandres
less than 70 years ago, has grown into a full-fledged cinder cone
nearly a thousand feet tall over the last several decades, and is
still growing.
[* - For real! I swear! It's on the map!]
Naturally, Materans don't live on the slopes of volcanoes that are
active on a regular basis ... unless the eruptions consistently
direct themselves in one direction, in which case the exceptional
fertility of volcanic soils may take precedence over the risk of
ashfall, on the mountain's opposite flank. Cities in the Hollow
Moon tend to be built in upland regions where vulcanism is minimal,
in places sheltered from lava flows or mudslides and upwind from
fumaroles; offshore basalt islands on the eastern seas or Midland
Ocean, where volcanic activity doesn't occur, are also at a premium
as locations for permanent habitation. Villages tend to be a bit
less picky about their sites, as even the most-settled of cultures
tend to keep relocation in mind when building smaller settlements.
Many farming or fishing communities will actually occupy two
different sites: a "working-village" near their crops or fishing
grounds, to which able-bodied folk commute for periods of a few
sleeps or a half-month at a time, and a "living-village" for
children, the elderly, and their caregivers and protectors.
Valuables, shrines, and the like are kept in the living-village,
which is situated in a geologically-secure spot. If vulcanism
threatens the croplands or mudslides foul the river, the
working-village's site is packed up and abandoned, and a new place
to farm or fish is established as soon as the Fire Time ends.
Divinations unique to the Hollow Moon setting allow Materan priests
or shamans to predict how long a site near an active or semi-active
volcano will be geologically safe to occupy, although the exact
nature of the disaster which will eventually render it unsafe --
lava, gas, tremors, ashfall, etc -- is not revealed. Such
divinations aren't 100% reliable, but they are designed to err on
the side of safety, indicating a disaster is forthcoming if there
is even a shadow of a doubt; too many "false alarms",
unfortunately, may cost a priest credibility, and cases of outright
fraud by land-grabbing clergy are not unknown.
For the most part, Mystaran PCs will find lunar people astoundingly
unintimidated, even blasé, about volcanoes. However terrifying
they might seem to the people of the Known World, active volcanoes
are as ordinary -- and dependable -- a fact of life, to the Hollow
Moon's natives, as are the seasons of the year, to Mystara's folk!
The fact that eruptions are predictable to within a matter of
hours, months or years in advance, is what gives lunar folk this
confidence: so long as they know what's coming, and WHEN, they've
got all the time they need, to prepare for each eruption and the
resulting disruption of their environment. Crops can be safely
harvested, before ashfall buries the fields (and seed sown, as soon
as the fertile ash cools down!); boats can be beached, or taken up
a safe tributary, hours before debris sweeps downriver from an
eruption-site (and then brought out again, to pick through the
debris for wood and other salvageable materials!) ; people can
clear out of areas where destruction is inevitable with time to
spare, bringing their possessions with them (and immediately start
planning what their next homes will look like ... a favourite
pastime, for Cacklogallinians!). In a very real sense, each severe
Fire Time is, to Materans, what winter is to Mystaran cultures -- a
time to be prepared for, and to stock up supplies in readiness
against; but also a time which heralds the rich renewal of the
land, and leaves an explosive rebirth of vegetation and animal life
in its wake. (Plus, it's only a few days out of an 18-month year,
for cryin' out loud! Mystarans get stuck with whole months of harsh
conditions, every winter ... a prospect which would absolutely
HORRIFY Materans. ;-D)
Other Fire Time Catastrophes
Aside from eruptions, volcanic activity during Fire Times has
similar consequences to that on Mystara or Earth. Here are a few
possible manifestations of geological unrest, for the Hollow Moon
setting:
Avalanches -- These occur quite regularly in the Mare Frigoris
region, in response to Fire Time ground tremors. Active or
semi-active volcanoes in the HM erupt too frequently for their
peaks to accumulate much of a snow-cap, but some dormant peaks which
experience tremors may unleash an avalanche as a result.
Earthquakes -- Because the Hollow Moon has no tectonic fault lines,
tremors tend to be confined to the immediate vicinity of major
eruptions. Characters will seldom, if ever, encounter a natural
earthquake that's as destructive as the Earthquake spell; most
tremors of significant size can flatten only flimsy structures such
as tents, yurts, animal pens or corrals. By law, all torches,
lanterns, ovens, forges and hearths in Cynidicea or the
Cacklogallinian trade-cities must be completely extinguished during
Fire Times, to prevent possible fires from breaking out due to
spilt embers.
Floods -- One of the few dangers that tend to crop up a few days
AFTER a Fire Time, flooding occasionally results from a river's
getting cut off from its usual course, be it by magma or by the
debris of a land- or mudslide. (At the same time, of course,
another region will be suffering from the loss of its now-diverted
river.)
Landslides -- Yet another response to tremors, these are especially
likely in areas of collapsed calderas such as the Taurus or
Caucasus Mounts, where the ground is mostly mounded rubble and
boulders. The deadliest of all volcanic eruptions, pyroclastic
flows, involve massive landslides of superhot debris from a
volcanic cone's blown-out wall; read up on Mt. Saint Helens, for
all the grisly details on these monster blasts.
Mudslides -- The bane of Hollow Moon rivers, these tend to occur
several hours after an actual eruption, when ash and dislodged
debris pour down the slopes of volcanoes into adjacent watercourses
and are carried downstream for miles. Trees and other standing
obstacles not strong enough to resist the force of flow are knocked
down and carried along with the mud, and may wind up floating in
the nearest lake or sea. Note that mudslides only occur in places
where water is already present; unlike volcanoes in other settings,
Hollow Moon volcanoes don't have snow-caps to melt and produce huge
swaths of mud which can flow down their slopes (the real cause of
most of the property-damage IRL volcanoes inflict).
Tsunami -- This is one disaster that virtually no area of the HM
setting is at risk for, simply because there are no continental
shelves along which giant waves can be uplifted! The flatness of HM
seabeds, which are of level crystal rather than contoured ground,
protects the vast majority of the setting's coastlines from
tsunami. The only two exceptions are the mouth of the Tauruntius
Strait, and Mare Humorum. The first of these locations is where the
deep waters of Tranquillitatis abruptly give way to the
coral-elevated seabed of Foecunditatis; tsunami can form if
tremor-generated waves pass from the former sea, to the latter, but
no vice versa. Such waves tend to strike the Foecunditatis
coastline from the equator to the Langrenus caldera. The second
spot where tsunami sometimes strike, Mare Humorum, can experience
such events because eruptions along its shores cause Venturer Deep
to void powerful upwellings of water, stirring up murk from the
Mare's mysterious seabed and sending colossal waves crashing
against every point on the steep Humorum coastline.