M5.0 – 25km NNE of Shawville, Canada

There was a moderate, Magnitude 5.0, earthquake in southern Ontario, Canada this morning.  It registered as a small but nicely formed signal on my seismograph in northeastern Ohio, showing the P, S, and surface arrivals.  The orientation of my seismograph makes it less sensitive to earthquakes north and south of my location than it is to earthquakes east or west of us.  By my calculation this earthquake was about 456 miles northeast of my location.

USGS Event page is here: http://earthquake.usgs.gov/earthquakes/eventpage/usb000gxna#summary

Postscript: 

The USGS reduced the magnitude estimate to 4.4 after this post was written.

M7.5 – 106km WSW of Craig, Alaska

A Major earthquake with a Magnitude of 7.5 occurred off the coast of southeastern Alaska today at 08:58:16 UT.  Initial estimates predict low property damage and loss of life due ground shaking but tsunami warnings are in effect for a long much of the coast of southeastern Alaska and British Columbia down to Vancouver Island.  The fault mechanism is shown to be a strike slip earthquake along what I think is a transform fault off the coast.  The worst tsunamis are generated by dip slip earthquakes occurring on thrust faults.

Here in Ohio, the signal from my seismograph dominates the helicorder display.  The extracted signal clearly shows the first arrivals of the P, PP, S, SS, and Love phases.  The PP and SS phases are reflections of the respective body phases off of the earth’s surface (from the inside of course).

One of my first thoughts was where the earthquake was in relation to the grounded Shell drilling rig near Kodiak Island.  My best estimate is that the rig is in a sheltered area about 725 miles west of the epicenter and probably (?) out of harms way from any tsunami.

M6.4 – 262km SSW of Avalon, California

A Strong, Magnitude 6.4 earthquake occurred this morning at 10:36:01 UTC off the west coast of Baja California.  The four principle arrivals, P, S, Love, and Rayleigh, all show very well in this signal.

M4.3 – 13km W of Whitesburg, Kentucky

A light earthquake of Magnitude 4.3 occurred in Eastern Kentucky shortly after noon today.  The epicenter was about 243 miles south southeast of my location in northeastern Ohio, giving a nice although small signal on my sensor.

Most of the reports were of light shaking; The USGS reported nearly 2000 responses to its Did You Feel It? website within 30 minutes of the rupture.

M7.7 – 139km S of Masset, Canada

A major earthquake with a magnitude of 7.7 occurred near Prince Rupert in the islands of Western Canada at 03:04:10 28 October 2012.  A small tsunami was generated which prompted evacuations of several small coastal/island communities.  The size, depth, and proximity to Ohio caused the signal on my seismograph to be off-scale for about 30 minutes.

New Page — Clear Sky Charts

With the transit of Venus rapidly approaching above cloudy skies I was very curious to see if the forecast was for clearing skies at the last minute.  My go-to website for that information is The Clear Sky Chart Homepage.   My experience has been that it is pretty accurate.  Then I realized that the authors permit embedding the chart on non-commercial websites like mine so I added a new page with charts for two locations on either side of my location in Millersburg, Stillwell and Wilmot, all in Ohio.  Find the new page in the sidebar at the right hand side of the page labeled “Clear Sky Chart“

The Shaking Continues – Magnitude 6.9 Gulf of California

Another major earthquake, a Magnitude 6.9 in the Gulf of California, overnight added to the unusual collection of strong earthquakes from yesterday.  I continue to have the display gain reduced to 1 on the helicorder of my seismograph here in northeastern Ohio.