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Hazard: Matterslip!

This article originally appeared in the August 2015 issue.

Shaansi hardly noticed the snap of cold air as she sped down the snow-covered slope. The wind on her face, the sunlight glinting off the ice, the sound of her skis atop the frozen blanket, the challenges of the backcountry—these gave her reason to live. Sure, she could get mostly the same effect with a gravboard, but there was nothing like the feel of skis against snow; of controlling her motion through friction and body-sense, not through electronics and computers. Her friends—especially the younger ones—couldn’t understand it, and she couldn’t explain it to them. It just was.

A gravboard’s advantage was that it was quieter. Shaansi didn’t want quiet. She wanted the sirrush of the skis as her constant companion. They drowned out all else: the sight of her father in that automed, her brother’s betrayal, the court’s decision… all lost in the sound and the blur of the slopes.

Unfortunately, the skis were also just loud enough to cover the first sounds of trouble. Shaansi missed the initial “thump” of the snowpack upslope separating. She became aware of the problem seconds later only as the barest hint of vibration and an increasing rumble. At first perplexed, her skier’s training quickly took over. A glance uphill showed her white impending hell.

Fighting panic, she poled hard toward a patch of trees, hoping to use them to break the avalanche’s power. The wall of snow loomed closer with each terrified glance at its progress.

Shaansi’s fear drove her. Harder! Faster! She poled with all her might. The world became a slow motion blur. The approaching avalanche. The approaching trees. The fleeing birds. The horrible roar of the disaster, however, wasn’t in slow motion; it steadily increased in volume, amping up her terror.

Almost there! Ten meters… five… then with a quickly-smothered scream of despair, she was brutally slammed away from hope and refuge. Her world became one of cold and pain as she was borne uncontrollably to an uncertain fate.

Gravity exists universally. What goes up must come down. Anything sitting on a slope—especially if that object is in a precarious position to begin with—will eventually find its way to the bottom of that slope. Sometimes with disastrous results.

Matterslips are constant dangers in any raised terrain such as mountains and foothills. Composed of a variety of substances, they also vary in their danger.

Author’s Note: while based on real-world science, the concepts presented here are part of a game. Nothing presented here is intended to be used in real-life situations. Matterslips (avalanches, landslides, rockslides, and mudslides) are dangerous phenomena that cause injuries and death, and are best avoided. When in ’slip-prone areas, always observe authorities’ warnings regarding their potential and the areas where they are likely to occur.

Defining a Matterslip

Matterslip is an umbrella term coined by Imperial scientists to describe a quickly-moving surge of material (including snow, rocks, earth, or mud) down a slope. The most stereotypical variant is an avalanche, a matterslip composed mainly of snow. Matterslips are also known (depending on composition) as landslides, rockslides, and mudslides.

Just as matterslips vary, so do methods of classifying them. Indeed, each world has its own system; Imperial authorities typically utilize the local classifications. For our purposes, matterslips can be broadly categorized on a scale based on their destructiveness:

  1. Relatively harmless; no risk of injury
  2. Capable of burying, injuring/killing unprotected beings
  3. Capable of damaging/destroying/burying small vehicles (ex: ground cars) and small structures
  4. Capable of damaging/destroying/burying large vehicles (ex: ATVs, Ship’s Boats) and large structures
  5. Capable of damaging/destroying/burying starships or small towns
  6. Capable of damaging/destroying/burying anything in its path; an historical event

The Making of a Matterslip

Matterslips are among the most common of natural hazards. All that’s needed are some form of solid matter, a slope of 30-45 (steeper slopes prevent accumulation; shallower slopes prevent the generation of the force necessary for the ’slip’s power), and gravity. Usually the material involved is in a precarious position atop or along the slope, with either a stress fracture running through some part of it or part of its mass unsupported. When a trigger event occurs, a portion of the matter breaks loose and cascades downslope. Triggers can be anything that provides enough shock or resonance to cause a mechanical failure of the unsupported material; this is often seismic activity, but can include water erosion, human or other sapient activity, or volcanic action. Contrary to popular belief, matterslips cannot be caused by loud sounds; the trigger must be mechanical in nature.

Once begun, the ’slip builds by collecting other materials. In the beginning this is merely more snow, rocks, or whatever else the ’slip is composed of, but plant matter, vehicles, and structures in the disaster’s path are also borne along if the ’slip is large and powerful enough. Most matterslips grow in size and intensity as they go, and can become quite large. A massive avalanche triggered by a strong earthquake struck the nation of Peru, on Terra’s South American continent, in -2548 (1970 CE). The avalanche, 61 million cubic meters of material measuring over 900 meters wide and 17 kilometers long, buried two towns and killed over 20,000. An even larger matterslip on Terra’s North American continent in -2505 (2013 CE) claimed no lives but measured 126 million cubic meters, shut down a copper mine, and fell into a 1.6 kilometer deep pit so hard that earthquakes were recorded.

Fortunately for potential victims, matterslips are short-lived. They move fast, and can reach speeds of 128 kph in 5 seconds. One can be over and done in the space of just a few combat rounds.

Surviving a Matterslip

It is possible to survive a matterslip. The best way also happens to be the most common way: don’t be in the path of one. This includes staying alert to the possibility of a ’slip:

Regardless of the type of matterslip, a common survival tactic is to move from the ’slip’s center path as quickly as possible; the most force and fastest speeds usually happen in the middle of the ’slip.

If an adventurer is caught by surprise and/or moving aside isn’t possible, survival depends on the nature of the ’slip:

Landslides, mudslides: the hero should curl up into a tight ball while protecting his or her head, including wearing a helmet. If within a multi-level structure, the hero should climb to the second level; this also removes him or her from the debris path.

Rockslides: the hero should get as close as (s)he can to the slope, protect the head, and not look up.

Avalanches: Surviving an avalanche is a bit more involved. Many avalanches are triggered by the victim or companions. If the snow fractures underfoot, jumping upslope past the fracture may be enough to avoid being caught in the ’slip. Heroes also should shed extra weight (such as backpacks, extraneous equipment, etc.) quickly in order to become as lightweight as possible. If the adventurer can grab onto a nearby object, this can prevent being carried away and buried if the avalanche is small. If escape or holding on isn’t possible, the adventurer should begin swimming (yes, swimming) in order to stay closer to the surface of the snow. Adventurers who become buried are up against the clock; hypothermia and suffocation are certain unless rescue is nearby. Buried victims should dig an air pocket in front of their face (to prevent suffocation) and conserve their energy. While it’s possible for the PC to dig him or herself out if near the snow’s surface, in most cases rescue must come from outside.

Aftermath of a Matterslip

A matterslips usually passes quickly. Once it has passed, the responses to the aftermath are usually the same, regardless of world or tech level: locate and rescue survivors (if any) and leave the area. Although a matterslip’s danger may appear over, there may be more ’slips if the terrain is unstable or being affected by severe weather. Mudslides in particular often occur in multiples.

Matterslips are a strictly local phenomenon, so their economic and environmental impact is relatively small. Avalanches can take a toll on arctic tourism, but usually occur in wilderness areas where guests can be easily steered away from dangerous zones. Mudslides and landslides are another matter. Either can occur in urban or otherwise-developed areas, taking homes and shops with them. The economic impact in this case is far more immediate and painful. The stricken area can take months to recover from a severe ’slip, especially if essential services were also affected. Mudslides can affect infrastructure, with mud overwhelming commerce and sanitation facilities, burying roads, clogging or destroying waste treatment facilities, and destroying cropland. Naturally, a sufficiently large ’slip can completely bury entire towns.

Refereeing a Matterslip

To begin, the referee must decide on the angle of the slope. Remember that matterslips occur on slopes of 30-45; for simplicity, the referee should decide on either 30 or 45. The severity of the matterslip is also a factor; using the categories above, the referee can assign a severity or determine one by throwing 1D.

As noted, matterslips rarely just happen; there is usually a trigger. In the case of an avalanche, that trigger is often sapient activity. If the PCs are moving through an avalanche zone, a throw of 6+ means one or more of the party has triggered a break of the snow’s fracture zone (DMs: +2 for heavy activity such as combat, +4 if they are deliberately trying to start one). If the trigger throw succeeds, each PC may immediately throw DEX or less to jump upslope and avoid being carried downslope.

Mudslides are more random. Sapient activity doesn’t trigger one; they occur in a region of heavy rain or flooding. If either of these conditions exists, and there is sufficient slope (see above), throw 7+ for one to occur (DMs: +1 for every 15 minutes of heavy rain, +1 if the slope is 45).

Landslides can happen very quickly, with the land suddenly sliding out from under creatures and structures, or they can happen over time. Once one begins, however, they behave as any other matterslip. The referee should decide whether the landslide is fast or slow. If fast, then it uses the same chances of being triggered as a mudslide (above), with the same DMs. If the landslide is slow, the referee should use a DM of +1 per day of heavy rain rather than every 15 minutes.

The referee should also consider the terrain. A mudslide obviously can’t happen on a snow-covered slope, for instance.

A matterslip, once triggered, moves quickly—its speed is 10D meters per second. The referee should decide how far it has to travel to reach the victim—which establishes their reaction time—and the total distance to the bottom of the slope.

To calculate a matterslip’s damage, use the following procedure:

Plug the results into the following equation:

(SL)(SP)(category)(composition, if solid)

This gives the dice of damage the ‘slip does to whatever is in its path. It hits as a Club, and uses the same armor matrix (Book 1: Characters and Combat). Armor protects normally. If the PCs move to either side of the ’slip, where the force is less—or in the case of a land- or mudslide, curl into a tight ball—halve the damage. If they use trees, rocks, and other objects as cover, treat such objects as Cloth armor.

The victims are carried along by the matterslip for 1D-2 combat rounds. Multiply this by the meters per second (above) to determine the distance. If the damage done is greater than the sum of the hero’s STR, DEX and END, (s)he is then buried and takes 1D of suffocation damage per minute (4 combat rounds) unless rescued.

Forecasting a Matterslip

Scientists have studied the causes and the preceding conditions of matterslips, and can forecast them with some degree of reliability. PCs who closely monitor local weather conditions can often make these forecasts themselves. Electronic sensors may even give them a reasonable timeframe in which a ’slip will happen (for example, using sensors to detect and monitor the fracture zones in large snow deposits.)

“I happen to know something about matterslips…”

Naturally, PCs with the most knowledge of and experience with matterslips are those who have lived or worked in ’slip-prone areas; especially avalanche zones, where knowledge of them is crucial to protecting slope-goers. Such individuals include wilderness guides, park rangers, game wardens, conservationists, geologists, and anyone else who spends a great deal of time in the outdoors.

Some Traveller careers are suited as background for a hero professing knowledge of matterslips. Scientists (Supplement 4: Citizens of the Imperium) are obviously knowledgeable, but Hunters—who necessarily spend time outside tracking bounty across varied terrain—would have at least a passing knowledge of ’slips and their triggers. Barbarians may know the locales to avoid by intuition, or simply knowing the history of the area if prone to regular matterslips.

Several skills are useful in dealing with matterslips: Computer skill allows modeling to determine which areas are in danger of burial or destruction, with an eye toward mitigation or prevention. Demolition skill (Supplement 4: Citizens of the Imperium) lets heroes place charges or artillery in ways that grant control of a resulting ’slip, or trigger one prematurely to prevent a worse one. Electronics skill allows for the use of scanners to detect fracture zones, approaching weather that may increase the chances of a ’slip, and quick detection of victims. Recon skill gives the ability to spot conditions that lead to ’slips and plan routes to avoid them. Survival skill is also invaluable for this, as well as specific survival techniques and rescue operations.

The Matterslip’s Impact on the Game

Referees can use a matterslip in much the same way they can use any other natural occurrence: as a direct threat to challenge the PCs; as background or a preliminary to an adventure; as an additional obstacle to overcome during an adventure; and even as a deus ex machina in case the adventurers get stuck.

Ship’s Locker

Avalanche Beacon
(7) Cr150. A miniaturized beacon that transmits a constant signal to aid in the location and rescue of buried avalanche victims. At tech level 9+, the signal includes inertial guidance and vital signs reporting. Mass negligible.
Rescue Airbag
(8) Cr500. A backpack device that deploys by use of a ripcord to prevent burial in an avalanche. The airbag inflates, allowing the victim to float to the surface of the snow. At tech level 9, the bag comes with sensors that trigger the airbag automatically imminent burial is detected. Mass 2kg.