Mount St. Helens Erupts (May 18, 1980)

We were living on East Pender, near Commercial Drive, in Vancouver, BC when this event happened. So, you could say, we had a front row seat, but from a great distance away. Once seen, never forgotten.

This is the exact timing of the first eruption. In terms of planetary influences, I might suggest that the background noise was Mars and Jupiter conjunct in Virgo. But a single line from the analysis of the only inconjunct might tell the truth. Or perhaps not.

Moon Inconjunct Neptune

Do not act as if you are the victim of strong forces that you can’t control, because you can control them.

As May 18 dawned, Mount St. Helens’ activity did not show any change from the pattern of the preceding month. The rates of bulge movement and sulfur dioxide emission, and ground temperature readings did not reveal any changes indicating a catastrophic eruption. USGS volcanologist David A. Johnston was on duty at an observation post around 6 mi (10 km) north of the volcano: as of 6:00 am, Johnston’s measurements did not indicate any unusual activity.

At 8:32 am, a magnitude-5.1 earthquake centered directly below the north slope triggered that part of the volcano to slide, approximately 7–20 seconds after the shock, followed a few seconds later by the main volcanic blast. The landslide, the largest subaerial landslide in recorded history, traveled at 110 to 155 mph (177 to 249 km/h) and moved across Spirit Lake’s west arm. Part of it hit a 1,150 ft-high (350 m) ridge about 6 mi (10 km) north. Some of the slide spilled over the ridge, but most of it moved 13 mi (21 km) down the North Fork Toutle River, filling its valley up to 600 feet (180 m) deep with avalanche debris. An area of about 24 sq mi (62 km²) was covered, and the total volume of the deposit was about 0.7 cu mi (2.9 km³).

Landslide and climatic phase (Wikipedia)

This picture is worth a thousand words.