Geological Oddities

Drake has been observing the constant change of Glacier Bay National Park for now two decades.

5.7 Earth Quake in Glacier Bay National Park

6/8/2014

A 5.7 magnitude earthquake rocked southeastern Alaska, about 73km from Haines, near Glacier Bay National Park and Preserve.

The earthquake hit on Wednesday at 11:58 GMT southwest of Haines, which has a population of over 2,500 people. The epicenter was 10km deep, according to United States Geological Survey.

The quake was first reported at a magnitude of 5.8, however it was subseqently downgraded to 5.7.

There have been no reports of casualties.

The circum-Pacific seismic belt, the earth’s most active seismic feature, brushes Alaska and the Aleutian Islands, resulting in frequent earthquakes. More than 80 percent of the planet’s tremors occur in the circum-Pacific belt, according to USGS data.

La Perouse Landslide

On February 16th 2014 a significant landslide was recorded (2.8 richter scale). Drake caught wind and flew to the site in Glacier Bay National Park. The slide ran off Mount La Perouse six miles to the Brady Glacier.

Dr Colin P. Stark Lamont Associate Research Professor at Lamont-Doherty Earth Observatory of Columbia University is cited below.

We first spotted the slide seismically on Sunday (using the Global CMT rapid detection system run by Göran and Meredith Nettles) and then started to look for confirmation elsewhere. Oddly enough, this event did not get an AEIC detection, whereas the 2012-06-11 event did (with an ML~3.8) – I say oddly, because Sunday’s event was apparently rather larger at Msw~5.0 compared to 2012’s Msw~4.8. Since neither was a fault slip event there is no particular reason why either should have been detected in this or any other catalog.

Here is our best estimate of the landslide location according to Clément and Göran’s “Landslide Force History” (LFH) inversion carried out on Mon/Tues – at 58.68, -137.37. It’s ~23km from Mt La Perouse and about 10km south of the Mt Lituya slide. Given the uncertainty in location estimation of the LFH, Mt La Perouse is plausible as a failure site, although a bit further than usual. To compare, our LFH estimate of the Mt Wrangell 2013-07-25 event was only 5km away from the landslide center (as first spotted by Jesse Allen in a L8 image).