{"id":8403,"date":"2019-03-26T22:22:02","date_gmt":"2019-03-27T06:22:02","guid":{"rendered":"http:\/\/earthjay.com\/?p=8403"},"modified":"2024-03-26T16:36:30","modified_gmt":"2024-03-26T16:36:30","slug":"earthquake-report-northern-alaska-2","status":"publish","type":"post","link":"https:\/\/earthjay.com\/?p=8403","title":{"rendered":"Earthquake Report: Northern Alaska"},"content":{"rendered":"

At shortly before 13:30 today in northern Alaska there was a large earthquake, with a magnitude of M=5.1 (now M 5.0).<\/p>\n

https:\/\/earthquake.usgs.gov\/earthquakes\/eventpage\/ak0193wxcfea\/executive<\/a><\/p>\n

Many of us are familiar with the Good Friday earthquake, a megathrust subduction zone earthquake. This earthquake has a birthday tomorrow, from 27 March, 1964 (55 years ago).<\/p>\n

The M=9.2 1964 temblor created a tsunami that traveled across the Pacific Ocean. More about the Good Friday earthquake and tsunami can be found here<\/a>.<\/p>\n

Alaska has a variety of major fault systems in addition to the subduction zone. There are also large strike-slip faults (move side by side) such as the Denali fault and the Kaltag fault. There are even more strike slip systems too, like the Queen Charlotte \/ Fairweather fault in southeastern Alaska and the Bering-Kresla shear zone<\/a> in the extreme western part of the Aleutian Islands. Alaska is so cool, they even have extensional (normal) earthquakes, such as on 1 December 2018<\/a>.<\/p>\n

Recently, there was a series of strike-slip earthquakes in the Gulf of Alaska<\/a> probably related to reactivation of pre-existing structures in the Pacific plate. We continue to have aftershocks in this area.<\/p>\n

Also, there is an ongoing sequence of earthquakes (now, maybe it is a swarm?) in northeastern Alaska<\/a>. The largest quake was in August last year (2018), with a magnitude of M=6.3.<\/p>\n

Today’s earthquake happened away from one of the mapped faults in the USGS Quaternary Active Fault and Fold Database (the Kaltag fault). The earthquake mechanism shows this earthquake may have been a slightly oblique normal type of an earthquake. I placed strike-slip arrows on the 2 possible nodal planes.but this is mainly a normal earthquake.<\/p>\n

There was also a normal earthquake in 1958, when a M=7.1 quake struck about 50 km (35 miles) to the southeast of today’s quake. However, the 1958 event was oriented perpendicular to today’s quake. Below are some observations made following the 1958 earthquake. There was evidence of liquefaction, with sand volcanoes about a meter thick extending for hundreds of meters laterally.<\/p>\n

Below is my interpretive poster for this earthquake<\/font><\/h2>\n

I plot the seismicity from the past month, with color representing depth and diameter representing magnitude (see legend). I include earthquake epicenters from 1918-2018 with magnitudes M \u2265 3.0 in one version.
\nI plot the USGS fault plane solutions (moment tensors in blue and focal mechanisms in orange), possibly in addition to some relevant historic earthquakes.<\/p>\n