Coastal cliff collapse, bluff erosion, and permafrost thaw¶

Coastal cliffs, marine bluffs, and Arctic or sub-Arctic permafrost slopes appear solid and permanent, yet they are among the most dynamic and unstable landforms on Earth. Unlike gradual inland hillside creep, coastal cliff collapses and permafrost thaw slumps frequently occur as sudden, catastrophic block topples, rotational slumps, or high-velocity debris avalanches with zero audible warning prior to failure. Every year, beachgoers walking or sitting beneath towering sandstone or chalk cliffs are buried alive by thousands of metric tons of falling rock, while hikers and sightseers standing near overhang rims plunge to the base when undercut ledges shear away beneath their boots.

In northern latitudes and high-alpine zones, rapidly warming air and ocean temperatures are accelerating thermokarst degradation, ice-wedge melting, and retrogressive thaw slumps. When ice-rich permafrost thaws, soil that was once as hard as concrete loses its structural cohesion and liquefies into an unstoppable mud slurry, swallowing roads, fracturing building foundations, and collapsing entire riverbanks and coastal bluffs into the sea within hours. Recognizing the visual precursors of slope failure, maintaining strict safety buffers above and below coastal bluffs, executing immediate self-rescue if caught in a collapse, and evacuating undermined buildings before structural shear occurs are critical life-saving skills.

ເຮັດອັນນີ້ດຽວນີ້¶

1. Step back immediately from any cliff rim, overhang, or freshly cracked ground. Move inland at least 5 to 10 meters (16 to 33 feet) away from the edge, or a horizontal distance backward equal to the vertical height of the cliff if the bluff consists of loose sand, clay, glacial till, or thawing permafrost.
2. Flee toward the water or laterally along the shoreline if a cliff begins crumbling above you on a beach. Never run straight along the base of the cliff; sprint directly toward the surf line to get outside the rockfall runout zone, watching behind you for bouncing boulders and secondary slides.
3. Protect your head and torso in a fetal ball if you are caught in an active slide and cannot escape. Drop to your knees, curl into a tight ball facing away from the falling slope, wrap your forearms over your neck and skull, and create a breathing pocket in front of your face with your hands if loose sediment covers you.
4. Evacuate any coastal or permafrost building immediately if doors jam, floors tilt, or foundation cracks widen rapidly. Do not pause to pack belongings if you hear loud popping, creaking, or snapping sounds in wooden framing, or if you observe tension cracks opening in the yard between the house and the bluff edge.
5. Shut off main natural gas, propane, and electrical utilities only if the valves are located safely inland. Never walk onto a cantilevered deck, undermined patio, or subsiding ground near the slope crest to turn off a utility meter; ruptured gas lines in shifting earth create immediate explosion hazards.
6. Never dig into the toe of a collapsed cliff with bare hands without a dedicated spotter watching for secondary falls. Freshly sheared cliff faces almost always release deadly secondary rockfalls within minutes of the initial collapse; call your local emergency number (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom) or check ຕົວເລກສຸກເສີນ and wait for technical rescue teams.

flowchart TD
    Start["Coastal Bluff, Cliff, or Permafrost Slope Hazard"] --> Location{"Where are you located?"}
    Location -->|"On Top of Cliff / In Building"| TopCheck{"Are there tension cracks, falling pebbles, or structural popping?"}
    Location -->|"On Beach at Base of Cliff"| BaseCheck{"Are pebbles trickling, dust puffs rising, or rocks cracking?"}
    Location -->|"On Thawing Permafrost / Thermokarst"| PermaCheck{"Is ground spongy, slumping, or showing exposed ice lenses?"}
    TopCheck -->|"ແມ່ນແລ້ວ"| EvacInland["Retreat straight inland away from rim, shut off gas if safe, call 911 / 112 / 999"]
    TopCheck -->|"ບໍ່"| BufferTop["Stay behind barriers, keep dogs on leash, stay 5 to 10 meters (16 to 33 feet) back from edge"]
    BaseCheck -->|"ແມ່ນແລ້ວ"| SprintSurf["Sprint straight toward the ocean surf or laterally away from the slide path immediately"]
    BaseCheck -->|"ບໍ່"| BufferBase["Walk near the waterline at least 1 to 2 cliff heights away from the bluff base"]
    PermaCheck -->|"ແມ່ນແລ້ວ"| RetreatHigh["Retreat uphill to firm vegetated tundra or bedrock, avoid mud slurries"]
    PermaCheck -->|"ບໍ່"| MonitorGround["Test ground firmness with a probe, stay clear of undercut riverbanks and ice wedges"]
    SprintSurf --> Trapped{"Were people buried in the debris fan?"}
    Trapped -->|"ແມ່ນແລ້ວ"| SpotterRescue["Call 911 / 112 / 999, assign a cliff spotter for secondary falls, probe surface debris only if safe"]
    Trapped -->|"ບໍ່"| StayClear["Stay at least 50 meters (165 feet) away from the fresh scar; secondary collapses are imminent"]

Mechanisms of cliff collapse, bluff erosion, and permafrost thaw¶

Understanding the geological mechanics driving slope instability explains why a cliff that has stood unchanged for decades can collapse in seconds on a calm, sunny afternoon. Different geological formations fail through distinct physical processes, each carrying unique warning signs and runout distances.

The two-fronted assault on coastal bluffs¶

Coastal cliffs fail because they are attacked simultaneously from the ocean side and the landward side:

1. Marine undercutting at the toe: During high tides and storms, breaking waves hurl sand and cobbles against the cliff base while compressing air inside fissures at pressures exceeding 300 kilopascals (43 pounds per square inch). This carves a concave wave-cut notch at the base, leaving the upper cliff hanging unsupported as a cantilever beam.
2. Groundwater saturation at the crest: Rainwater, snowmelt, leaking pools, and septic systems infiltrate the top of the bluff and percolate down to impermeable clay layers. High pore-water pressure pushes soil grains apart, destroying shear strength while adding weight, often triggering fair-weather collapses weeks after a rainstorm.

Spotting pre-collapse warning signs on cliffs and bluffs¶

Before a cliff face or coastal bluff shears away, the stressed rock or soil exhibits physical deformations that give you critical minutes to evacuate.

Visual and audible indicators from the cliff top¶

When walking along coastal trails or clifftop properties, scan the ground 3 to 15 meters (10 to 50 feet) back from the rim:

• Tension cracks and arcuate fissures: Narrow cracks running parallel to the cliff edge or curving in a crescent shape through grass or pavement. Fresh, moist soil or torn white plant roots inside a crack mean the ground is actively pulling away.
• Vertical step-offs (scarplets): Where the seaward side of a crack drops 2 to 10 centimeters (1 to 4 inches) lower than the landward side, rotational slumping has begun.
• Overhanging turf mats and undercut rims: Grassy sod held together by roots often projects 1 to 2 meters (3 to 6.5 feet) out over empty space after underlying sand or chalk has fallen away.
• Tilted fences, leaning trees, and stretched utility lines: Fence posts leaning seaward, pulled-apart asphalt cracks, or tilted trees indicate active slope creep.
• ** ຂຸມຝັງສົບຢູ່ເບື້ອງຫຼັງຂອບໜ້າຜາ:** ຮ່ອງລະບາຍນ້ຳເປັນວົງມົນທີ່ມີຄວາມເລິກ 5 ຫາ 20 ແມັດ (16 ຫາ 65 ຟຸດ) ຢູ່ໃນນ້ຳ ຊີ້ບອກໃຫ້ເຫັນຫຼັງຄາຖ້ຳທະເລທີ່ບໍ່ເຫັນໄດ້ພັງລົງມາທາງເທິງ ຫຼື ດິນເຊາະເຈື່ອນ.

Visual and audible indicators from the beach below¶

When walking along a narrow beach bordered by cliffs, continuously monitor the vertical face above you:

• Trickling pebbles and dust puffs ("rock rain"): Shearing along rear fracture planes squeezes loose sand, pebbles, and dry dust out of cracks right before detachment. Falling pebbles or dust puffs signal an imminent major collapse.
• Freshly exposed, unweathered rock patches: Weathering and algae coat stable cliffs in muted tones. A bright white scar on chalk or clean fracture on sandstone means a recent rockfall has left adjacent overhangs unsupported.
• Groundwater seepage lines and wet dark bands: Horizontal dark stripes of wet clay or dripping water mid-bluff mark internal erosion and lubricated slip planes.
• Talus cones and fresh debris aprons: Piles of jagged boulders or slumped mud at the cliff foot prove active instability above.
• Audible cracking, popping, or rumbling: Stressed rock emits sharp cracks or deep thuds as internal rock bridges snap prior to full detachment.

Immediate survival actions during an active cliff collapse¶

If you hear a sudden roar, feel the ground shudder, or see a cliff face detaching, you have between 2 and 8 seconds to react before debris reaches the beach or the rim gives way.

1. If you are on the beach below a collapsing cliff¶

1. Look up for a split second to identify the failure zone, then sprint toward the ocean: Unlike inland landslides where you should never run downhill, on a coastal beach the ocean surf is your safest refuge. Run directly away from the cliff face toward the water, or sprint diagonally along the shoreline away from the falling section if the collapse is narrow.
2. Clear the horizontal runout zone: Falling rock masses shatter upon hitting the base and project horizontally across the sand at speeds exceeding 50 kilometers per hour (31 miles per hour). In dry rockfalls, fragments typically travel outward a horizontal distance equal to 0.5 to 1.0 times the vertical height of the cliff. In wet clay bluff slumps or saturated chalk collapses, the liquefied debris lobe can surge outward 1.5 to 3.0 times the height of the cliff, crossing the beach into the surf zone.
3. Enter the shallow surf if necessary, but watch for displacement waves: If the beach is narrow and the slide is massive, run into waist-deep water to avoid crushing rock debris. Brace yourself against the seabed, because thousands of tons of rock plunging into shallow water can generate a localized displacement wave and strong backwash currents.
4. If rock fragments are raining down and you cannot outrun the slide: Never lie flat on your stomach on the sand, which exposes your spine and skull to maximum impact. Duck behind the seaward side of a massive boulder if one is sitting away from the cliff base, or drop to your knees facing the ocean, curl into a tight fetal ball, interlock your fingers behind your neck, and pull your knees up to protect your chest and organs.
5. If buried in loose sand or bluff soil: Keep your mouth closed while sediment is moving, cup your hands in front of your nose and mouth to create an air pocket, and expand your ribcage deeply as the slide slows down so your chest has room to breathe before the wet sediment sets.

2. If you are on top of the cliff when the ground gives way¶

1. Drop everything and scramble straight inland on all fours: If you feel the ground lurch downward or see a crack opening between your feet and the mainland, leap or dive across the crack toward the inland side immediately. Crawling on hands and knees keeps your center of gravity low so you do not tumble backward over the edge.
2. Grab anchored inland vegetation, never edge vegetation: Reach for tree trunks, fence posts, or bushes rooted firmly on the landward side of the tension crack. Never grab bushes growing on the collapsing block itself, as their roots will pull you down with the falling slab.
3. If you are riding a collapsing slump block downward: A rotational slump often slides downward along a curved plane while keeping its grassy top surface tilted slightly backward toward the cliff face. Stay on top of the moving turf block rather than jumping off the front edge where you will be crushed at the toe, then scramble off the side of the debris mound toward the waterline as soon as it stops.

3. Watch for deadly coastal tidal cutoff¶

A major cliff collapse often dumps an enormous mound of clay, trees, and boulders all the way across the beach into the low-tide surf zone, blocking the coastal walking route.

• Never scramble over a fresh, unstable landslide lobe to get back to your starting stairway if the cliff above is still shedding rocks.
• Check the tide state immediately: If the tide is rising and a cliff collapse blocks one side of a cove while a rocky headland blocks the other, you face tidal cutoff (being trapped against the vertical cliff by rising water). Call 911, 112, or 999 (and request the Coast Guard or RNLI lifeboat) immediately while you still have dry sand, climb onto the highest stable rock outcrop away from the fresh scar, and wave bright clothing to guide rescue boats.

Permafrost thaw, thermokarst, and Arctic slope emergencies¶

Permafrost is ground (soil, sediment, peat, or rock) that remains at or below 0 degrees Celsius (32 degrees Fahrenheit) continuously for at least two consecutive years. Across Alaska (United States), northern Canada, Greenland, Scandinavia, the European Alps, and Siberia, rapid warming is destabilizing the active layer (the top 30 to 150 centimeters / 1 to 5 feet of soil that thaws every summer and refreezes in winter) and melting the deeper permafrost table beneath it.

Escaping liquefied permafrost silt (thermokarst mud entrapment)¶

When ice-rich Pleistocene silt thaws rapidly in a retrogressive thaw slump or coastal bluff collapse, it releases more water than the soil pores can hold. This creates a thixotropic mud slurry that looks like firm grey clay under a thin sun-dried crust but behaves like liquid silt underneath.

1. If you break through the crust into deep permafrost mud: Do not thrash or try to walk forward, which drives your legs deeper into the frigid 1-degree-Celsius (34-degree-Fahrenheit) slurry.
2. Drop your heavy backpack immediately: Unclip your waist belt and sternum strap and let the pack sit on the mud surface next to you as a flotation platform.
3. Spread your body weight horizontally: Lean forward or backward so your chest or back lies flat across the mud surface, distributing your weight over a wide area.
4. Free your legs one at a time: Work your legs slowly in small circular motions to let water seep down around your boots and break the vacuum suction. Never let a rescuer pull you straight up with a winch or ATV strap while your legs are locked in deep silt; dig around the trapped limbs first.
5. Swim or roll across the mud surface: Once both legs are horizontal on the surface, crawl on your stomach using a swimming motion or roll sideways toward solid tundra grass, then treat immediately for hypothermia.

Evacuating structures undermined by bluff erosion or thawing ground¶

Homes, apartments, roads, and industrial facilities built along eroding ocean bluffs, clay bluffs, river cutbanks, and thawing permafrost face sudden structural failure when slope retreat removes foundation support.

Structural red flags requiring immediate evacuation¶

Evacuate immediately if your building exhibits any of these structural failure signs during or after a storm, high tide, or rapid thaw:

• Cantilevered or hanging foundations: Any portion of a concrete slab, footing, pier, patio, or deck support post is visibly hanging over the cliff edge with air beneath it, or soil has washed away from pilings.
• Sudden jamming of multiple doors and windows: When the seaward side of a house settles toward the bluff face, wooden wall frames rack into parallelograms, pinching doors and windows shut and cracking drywall diagonally at 45-degree angles.
• Audible structural noises: Loud popping, snapping, creaking, or groaning sounds from wall studs, roof trusses, or floor joists indicate active load redistribution as ground support drops away.
• Separation of decks, porches, or chimneys: A gap of 1 centimeter (0.4 inches) or more opening rapidly between an oceanfront deck ledger board and the house wall, or a chimney leaning away from the siding, signals imminent detachment.
• Ruptured or stretched utility pipes: Hissing sounds or the rotten-egg odor of mercaptan from gas lines, gushing water from broken PVC pipes, or taut overhead electrical wires pulling at the mast.
• Rapidly retreating bluff rim: If a storm or slide brings the cliff edge within 3 to 5 meters (10 to 16 feet) of your foundation wall, the building is inside the active wedge of failure and is unsafe for occupancy.

Step-by-step building evacuation and utility isolation¶

1. Alert all occupants and exit through the inland (street-side) doors: Evacuate immediately toward the street or inland high ground. Never step out onto an oceanfront balcony, cliffside deck, or seaside patio to look at the erosion scar; cantilevered decks are often the first components to plunge down the cliff.
2. Grab only your emergency go-bag, medications, pets, and keys: Spend no more than 60 seconds exiting. Never move heavy furniture or appliances out of rooms on the cliffward side, as added live load can trigger floor collapse.
3. Shut off natural gas, propane, and electricity if the meters are safely inland:
4. If the gas meter or propane tank is on the street side on stable ground, use an adjustable wrench to turn the quarter-turn supply valve 90 degrees until the lug is perpendicular to the pipe (or close the propane handwheel clockwise).
5. Flip the main circuit breaker off at the electrical panel if it is accessible from a safe inland wall.
6. Shut off the main domestic water valve at the street curb box so a snapped pipe does not pump pressurized municipal water into the unstable bluff soil.
7. Never walk near the cliff edge or enter a tilting basement to shut off utilities. Retreat to the street and call your utilities and the fire department immediately.
8. Warn adjacent neighbors on both sides: Bluff slumps propagate laterally along the shoreline as your yard's slump removes lateral earth support for adjacent properties. Knock on neighbors' street-side doors and alert them to check their foundations.
9. Contact municipal building inspectors and geotechnical authorities: Call 911, 112, or 999 if there is immediate danger to life, gas leaks, or people on the beach below. Request a municipal building and geotechnical engineering inspection before re-entering.

ການ​ຊ່ວຍ​ເຫຼືອ​ແລະ​ການ​ດູ​ແລ​ດ້ານ​ການ​ແພດ​ຫຼັງ​ຈາກ​ໜ້າ​ຜາ​ພັງ​ລົງ¶

When a coastal cliff collapses onto a beach, a freshly sheared cliff face is out of mechanical equilibrium and frequently releases lethal secondary rockfalls over the next 5 to 60 minutes.

1. Scene safety and the mandatory cliff spotter rule¶

1. Call emergency services immediately: Dial 911, 112, or 999 and provide the beach name, access stairway number, cliff height, estimated casualties, and tide state. Request cliff rescue teams, the Coast Guard / lifeboat service, and air ambulance support.
2. Never rush blindly into the rockfall zone: Look up at the cliff scar before approaching. If rocks are still falling, if an overhanging slab is separated by a gaping crack above the debris pile, or if dust is billowing, stay back.
3. ** ກຳນົດຕົວເຝົ້າລະວັງສະເພາະຕົວ:** ຖ້າຜູ້ເຄາະຮ້າຍຖືກຝັງໄວ້ບາງສ່ວນຢູ່ຂອບນອກຂອງພັດລົມຂີ້ເຫຍື້ອ, ມອບໃຫ້ຄົນໜຶ່ງຢືນຢ່າງປອດໄພໃກ້ສາຍນ້ຳ, ແນມເບິ່ງໜ້າຜາ ** ສະເພາະແຕ່ຂຶ້ນໜ້າຜາ** ເພື່ອເຕືອນໄພທັນທີຫາກກ້ອນຫີນຫຼັ່ງໄຫຼ ຫຼື ໜ້າຜາປ່ຽນໄປ.

2. ສະກັດກັ້ນຜູ້ຖືກເຄາະຮ້າຍ ແລະ ປ້ອງກັນພະຍາດປວດ¶

ຖ້າເຈົ້າສາມາດເຂົ້າຫາຜູ້ເຄາະຮ້າຍໄດ້ຢ່າງປອດໄພຢູ່ຂອບນອກຂອງຂີ້ຕົມຂີ້ເຫຍື້ອ ໂດຍບໍ່ຕ້ອງຢືນຢູ່ຂ້າງລຸ່ມ:

• ** ລ້າງ​ທາງ​ເດີນ​ຫາຍ​ໃຈ​ແລະ​ຫນ້າ​ເອິກ​ກ່ອນ​ທີ່​ຈະ​:** ກວາດ​ດິນ​ຊາຍ​, ດິນ​ເຜົາ​, ຫຼື gravel ຫ່າງ​ໄກ​ຈາກ​ດັງ​, ປາກ​, ແລະ​ຫນ້າ​ເອິກ​ຂອງ​ຜູ້​ເຄາະ​ຮ້າຍ​ເພື່ອ​ໃຫ້​ປອດ​ຂອງ​ເຂົາ​ເຈົ້າ​ຂະ​ຫຍາຍ​ຕົວ​. ຜູ້ເຄາະຮ້າຍຈາກດິນເຈື່ອນ ແລະດິນຊາຍສາມາດຕາຍໄດ້ດ້ວຍ ອາການຫາຍໃຈຍາກ ພາຍໃນ 3 ຫາ 5 ນາທີ ເມື່ອດິນຊາຍປຽກຊຸ່ມຫຼາຍກົດໃສ່ກະດູກຄາງຂອງພວກເຂົາທຸກຄັ້ງທີ່ພວກເຂົາຫາຍໃຈອອກ.
• ຂຸດຢ່າງລະມັດລະວັງກ່ຽວກັບແຂນຂາທີ່ຕິດຢູ່: ໃຊ້ມື, ໄມ້ຫຼົ່ນ, ຫຼືຖັງປຼາສະຕິກຫຼາຍກວ່າຊ້ວນໂລຫະຢູ່ໃກ້ກັບສົບຂອງຜູ້ທີ່ຖືກຝັງໄວ້ເພື່ອບໍ່ໃຫ້ມີເນື້ອເຍື່ອທີ່ຂາດ.
• ສົງໄສວ່າເຈັບກະດູກສັນຫຼັງ ແລະ ເລືອດອອກພາຍໃນ: ຜູ້ໃດທີ່ຖືກກ້ອນຫີນຕົກລົງ ມີຄວາມສ່ຽງສູງທີ່ຈະເປັນປາກມົດລູກ. ການບາດເຈັບຂອງກະດູກສັນຫຼັງ, head injury, ແລະ ກະດູກຫັກ. ຮັກສາຫົວ, ຄໍ, ແລະກະດູກສັນຫຼັງໃຫ້ສອດຄ່ອງກັນ ເວັ້ນເສຍແຕ່ວ່າສະໄລ້ສຳຮອງທີ່ໃຊ້ງານໄດ້ຮຽກຮ້ອງໃຫ້ມີການລາກສຸກເສີນຕາມແກນຍາວຂອງຮ່າງກາຍໄປສູ່ການໂຕ້ຄື້ນ.
• ລະວັງເປັນໂຣກ Crush Syndrome ຖ້າກ້ອນຫີນໜັກຕິດແຂນຂາ ຫຼື pelvis ດົນກວ່າ 15 ນາທີ: ເມື່ອກ້ອນຫີນໜັກໄປທັບກ້າມຊີ້ນໃຫຍ່ເປັນເວລາດົນກວ່າ 15 ນາທີ, ການທຳລາຍກ້າມຊີ້ນຈະສະສົມທາດໂພແທດຊຽມ, myoglobin, ແລະກົດ lactic ທີ່ຕາຍແລ້ວ. ທັນທີທັນໃດການຍົກກ້ອນຫີນອອກຈາກແຂນຂາຍາວຈະປ່ອຍໂພແທດຊຽມເຂົ້າໄປໃນກະແສເລືອດ, ເຊິ່ງສາມາດເຮັດໃຫ້ເກີດການຈັບກຸມຫົວໃຈຕາຍ (ໂຣກ reperfusion). ປຶກສາແພດສຸກເສີນ ກ່ອນທີ່ຈະຍົກກ້ອນຫີນອັນໜັກໜ່ວງອອກຈາກຜູ້ເຄາະຮ້າຍທີ່ຕິດຢູ່ດົນກວ່າ 15 ນາທີ, ເວັ້ນເສຍແຕ່ວ່າກະແສນ້ຳທີ່ເພີ່ມຂຶ້ນ ຫຼື ການພັງລົງຂັ້ນສອງຈະຂົ່ມຂູ່ເຖິງການເສຍຊີວິດໃນທັນທີ, ແລະຄວບຄຸມຢ່າງຮ້າຍແຮງ. ເລືອດອອກ ດ້ວຍຄວາມກົດດັນໂດຍກົງຫຼື tourniquet.

ການຫຼຸດຜ່ອນຊັບສິນໃນໄລຍະຍາວແລະການກະກຽມການເຊາະເຈື່ອນ¶

If you live on a coastal bluff, lakeshore cliff, or permafrost terrain, proactive water management and geotechnical monitoring slow slope retreat and provide early warning.

1. Eliminate artificial water inputs near the bluff crest:
2. Disconnect lawn sprinklers and drip irrigation within 15 meters (50 feet) of the cliff edge.
3. Pipe roof gutters, downspouts, and driveway drains into sealed non-perforated pipes that discharge into an inland street storm sewer or all the way down the bluff face in an anchored high-density polyethylene (HDPE) tightline to the beach toe.
4. Never dump pool water or greywater onto a coastal lawn, and convert leaching septic fields near bluffs to sealed sewer connections.
5. Preserve deep-rooted native vegetation and ban cliff-edge dumping:
6. Never clear native coastal shrubs, dune grass, or deep-rooted trees at the top of a bluff to improve your view, as root networks bind soil and transpirate groundwater.
7. Remove heavy shallow-rooted invasive plants like ice plant (Carpobrotus edulis), which add dead weight to steep cliff faces and shear away in sheets.
8. Never dump yard waste or fill over a cliff edge, which traps moisture and hides tension cracks.
9. Install simple crack-monitoring stakes:
10. Drive two wooden stakes deeply into the ground on opposite sides of any hairline ground crack near a bluff and measure the distance between two nails on top of the stakes weekly with a steel tape measure.
11. If the gap widens by 5 to 10 millimeters (0.2 to 0.4 inches) over a few days, slope movement is accelerating; call a licensed geotechnical engineer immediately.
12. Protect permafrost foundations from thermal transfer:
13. Keep permafrost buildings elevated on adjustable pilings, passive thermosyphons, or thick gravel pads with at least 1 meter (3 feet) of airflow beneath the floor, and never strip the insulating tundra moss mat.

ຄຳຖາມທີ່ມັກຖາມເລື້ອຍໆ¶

ຄູ່ມືທີ່ກ່ຽວຂ້ອງ¶

• Landslides and mudslides
• Sinkholes and ground collapse
• Tsunamis: evacuation and survival
• ກະແສລົມ ແລະພາວະສຸກເສີນຂອງນ້ຳມະຫາສະໝຸດ
• ຄວາມ​ເສຍ​ຫາຍ​ດ້ານ​ໂຄງ​ສ້າງ​ແລະ​ການ​ພັງ​ທະ​ລາຍ​ຂອງ​ອາ​ຄານ​
• ປວດການບາດເຈັບແລະໂຣກ compartment

ກວດສອບແຫຼ່ງທີ່ມາ¶

• ການສຳຫຼວດທໍລະນີວິທະຍາຂອງສະຫະລັດອາເມລິກາ (USGS, ສະຫະລັດອາເມລິກາ): ການເຊາະເຈື່ອນຂອງຊາຍຝັ່ງທະເລ, ໂຄງການອັນຕະລາຍຈາກດິນເຈື່ອນ, ແລະ ການສຶກສາ Permafrost Thaw
• ການສຳຫຼວດທໍລະນີວິທະຍາຂອງອັງກິດ (BGS) ແລະອົງການ Maritime and Coastguard (MCA, ສະຫະລາດຊະອານາຈັກ): Geohazards Coastal, Cliff Instability, and Beach Safety Guide
• ຊັບພະຍາກອນທຳມະຊາດການາດາ (NRCan) ແລະ ການສຳຫຼວດທໍລະນີສາດຂອງການາດາ (ການາດາ): ການເສື່ອມໂຊມຂອງ Permafrost, ການຫຼຸດລົງຂອງຄວາມວຸ້ນວາຍ, ແລະຄວາມປອດໄພຂອງດິນເຈື່ອນ.
• ອົງການຄຸ້ມຄອງສຸກເສີນຂອງລັດຖະບານກາງ (FEMA, ສະຫະລັດ): ຄູ່ມືການກໍ່ສ້າງແຄມຝັ່ງທະເລ (FEMA P-55) ແລະການຄຸ້ມຄອງອັນຕະລາຍເຊາະເຈື່ອນ
• ໂຄງການຕິດຕາມ ແລະ ປະເມີນລະດັບອາກຕິກ (AMAP) ແລະ ອົງການອຸຕຸນິຍົມວິທະຍາໂລກ (WMO): ຫິມະ, ນ້ຳ, ນ້ຳກ້ອນ ແລະ Permafrost ໃນອາກຕິກ (SWIPA) ການປະເມີນດ້ານວິຊາການ