Turnagain Heights Slide

Turnagain Heights Slide (HM1BM0)

Location: Anchorage, AK 99530 Anchorage
Country: United States of America

N 61° 11.911', W 149° 58.802'

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Inscription
You are standing on the edge of the Turnagain Heights Slide, the largest and most destructive landslide in Anchorage.

Ninety seconds into the Good Friday Earthquake, an 8,000-foot strip of bluff, 1,200 feet wide began cracking apart into larger blocks which slid toward Cook Inlet. With a savage and grinding roll, the slide transported some homes 500 feet seaward, and broke apart or crushed other homes. Residents rushed outside their homes only to be thrown to the ground as the blocks pulled apart and heaved around them. Others were trapped in their homes. The slide movement continued for 90 seconds after the earthquake stopped shaking Anchorage. Over 12 million cubic yards of sand, clay and gravel slid off toward the inlet, 75 homes were destroyed, and four people perished.

Bootlegger Cove Clay
Underneath most coastal Anchorage is a deep layer of gray- blue material called Bootlegger Cove Clay. This silty plastic clay is composed of estuary-miarine sediment, and was deposited 15,000 to 30,000 years ago by massive glaciers that covered most of south-central Alaska. Unfortunately, it can be extremely soft and unstable. During an earthquake Bootlegger Cove Clay tends to liquefy and lose strength and where the upper clay layers contain loose sand layers, it can dramatically fail.
Details
HM NumberHM1BM0
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Marker ConditionNo reports yet
Date Added Saturday, October 4th, 2014 at 7:32pm PDT -07:00
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Locationbig map
UTM (WGS84 Datum)6V E 339867 N 6788549
Decimal Degrees61.19851667, -149.98003333
Degrees and Decimal MinutesN 61° 11.911', W 149° 58.802'
Degrees, Minutes and Seconds61° 11' 54.66" N, 149° 58' 48.12" W
Driving DirectionsGoogle Maps
Area Code(s)907
Closest Postal AddressAt or near 5247-5399 W Northern Lights Blvd, Anchorage AK 99530, US
Alternative Maps Google Maps, MapQuest, Bing Maps, Yahoo Maps, MSR Maps, OpenCycleMap, MyTopo Maps, OpenStreetMap

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