#43YearsAgo at #MSH: During 1980-86, scientific understanding grows by leaps & bounds. Better monitoring systems show volcanoes are inherently restless; scientists share a commitment to communicate hazards. Lessons learned from MSH must not—and will not—be forgotten. #volcano #usgs

#43YearsAgo at #MountStHelens: May 30, 1980
Lilies emerge from the ash. Restorative part of cycle, repeated many times at Mount St. Helens & other Cascade volcanoes, has begun. Travel in NW nearly normal. Scientists focus on hazard evaluation & how to live with active volcanoes. #volcano #usgs

#43YearsAgo at #MountStHelens: May 29, 1980
Activity has declined. The eruptive plume rising from the volcano's crater is a light gray mixture of ash and steam. Tiltmeters record no anomalous ground tilt. Seismicity is at its lowest since activity began in mid-March, 59 days ago. #volcano #usgs

#43YearsAgo at #MountStHelens: May 28, 1980
WA Governor accuses people killed in eruption of violating restricted zones. This is untrue for nearly all. People caught up in sideways blast skirted no roadblocks. They did nothing wrong. #volcano #usgs

#43YearsAgo at #MountStHelens: May 27, 1980
On I-5, ash from May 25 eruption makes driving tough. State Patrol sets emergency speed limit of 25 mph but drivers impatient. Truckers communicate by CB, maneuver rigs to form moving roadblocks. Drive speed limit to prevent accidents. #volcano #usgs

#43YearsAgo at #MountStHelens: May 26, 1980
Helicopter settles gingerly on deposit in valley & scientists get out to probe temperature. Nearly a week later, ash is still 300° F, 2 ft down. Chunks of glaciers entombed in lahar. Air full of strange smells; wood cooking in ash. #volcano #usgs

#43YearsAgo at #MountStHelens: May 25, 1980
Early AM eruption sends ash to Portland/Vancouver (as much as 1/4 in). While ash falls, rain starts, roads slick, airports closed, phone/power out. "Everybody started freakin..." stampede to store to stockpile food, supplies. #volcano #usgs

#43YearsAgo at #MountStHelens: May 24, 1980
Seismologists scour EQ records trying to find the pattern that would have foretold the eruption. There is none. Huge seismic buildup in March seemed to be wad of magma intruding into volcano. That event, in time, caused all others. #volcano #usgs

#43YearsAgo at #MountStHelens: May 23, 1980
In eastern WA, powdery ash blows everywhere. People stranded, motels full. Sheriffs start slow passage of motorists on I-90 West, releasing 1 car every 4 min. Drivers told to drive 20 mph. Stirring up ash reduces visibility. Accidents. #volcano #usgs

#43YearsAgo at #MountStHelens: May 22, 1980
President Carter flies over shattered houses, flood-swept lower valley, downed forest, debris avalanche; an explosion equating to 10 million tons of TNT. Carter remarks: “...moon looks like a golf course compared to what’s up there.” #volcano #usgs

#43YearsAgo at #MountStHelens: May 21, 1980
For scientists, days are a blur. Priority is to re-establish monitoring networks, map deposits, measure temperatures & collect samples. Each piece of the puzzle helps explain what happened on May 18 & what to expect in the future. #volcano #usgs

#43YearsAgo at #MountStHelens: May 20, 1980
Search and rescue continues. Ash closes schools, roads. Debris avalanche blocks Spirit Lake outlet and concerns grow about flood hazard downstream. A new chapter opens—the aftermath. #volcano #usgs

#43YearsAgo at #MountStHelens: May 19, 1980
Activity decreases overnight. Low seismicity & low level of tremor. Plume heights diminish (5,000-11,000 ft). Pyroclastic flows at times. Mudflows reported in North Fork Toutle River, South Fork Toutle and Pine Creek drainages. #volcano #usgs

#43YearsAgo at #MountStHelens: May 18, 1980
Bulge fails as clossal landslides. Magma & hot fluids explode, surge outward like hot hurricane. Column rises, ash falling. Hummocky debris flow buries valley. Snowpack melts, mudflows converge. 9-hr eruption. Everything is changed. #volcano #usgs

#43YearsAgo at #MountStHelens: May 18, 1980 6:30 PM
USGS' Glicken & Swanson duck out to escape radio, telephones. Don tells Harry about what he’d seen from the air, of David Johnston’s almost certain death. Exhausted, pilot Stickney joins them, confirms Coldwater II wiped clean. #volcano #usgs

#43YearsAgo at #MountStHelens: May 18, 1980 4:30 PM
A strong vertical blast rises into the stratosphere. Another at 4:45. At 5:12, the plume rises 4000 to 5000 ft/min. Eruption wanes after 8 PM & clouds pull back. Scientists glimpse a deep crater. A breach on north flank. #volcano #usgs

#43YearsAgo at #MountStHelens: May 18, 1980 3:30 PM
Search & Rescue frantic for survivors. 22 National Guard helicopters fly 101 sorties, 143 hrs; Wyoming Guard 15 hrs. Air Force Reserve 303rd aids with tracking, communications. Many Vietnam flyers. White-knuckle flying all day. #volcano #usgs

#43YearsAgo at #MountStHelens: May 18, 1980 2:45 PM
Reporters fly up North Fork Toutle to witness churning wall of mud, trees & debris destroy bridges, homes. Second mudflow of the day more destructive than first, peaks overnight at 49.5 ft, 16.1 ft higher than first mudflow. #volcano #usgs

#43YearsAgo at #MountStHelens: May 18, 1980 2:30 PM
Weyerhaeuser helicopters in air to assess logging camps, roads. Mudflow buries Camp Baker. Breeze clears clouds & they fly up Green River. All trees lay flat. Blowdown covers thousands of acres. #volcano #usgs

#43YearsAgo at #MountStHelens: May 18, 1980 2:15 PM
Pilot Dwight Reber’s mission—find Reid Blackburn at Coldwater I. He flies to Maratta Creek, a wild deposit of dunes, gorges, craters, & rising steam, & up steep slope to ash-covered ridge crest. No way anyone could survive. #volcano #usgs