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

Magnitude 4.0 – YOUNGSTOWN-WARREN URBAN AREA, OHIO

A Magnitude 4.0 earthquake was reported this afternoon at 20:04:58 UTC in northeastern Ohio.  This is in the same area as a sequence of earthquakes thought to be associated with injection wells used to dispose of oil drilling waste fluids.  The injection wells operations were suspended yesterday by the state of Ohio and the operator of the well.

Even though my seismograph in Millersburg, OH  is not well suited to picking up local earthquakes and the display has been quite noisy the last few days, with a small amount of processing I did pick up a signal that appears to be caused by the earthquake in question.

The USGS arrival time information is shown:

DATE-(UTC)-TIME    LAT    LON     DEPTH MAG   Q   COMMENTS
2011/12/31 20:04:58  41.16N  80.73W   2.2 4.0      us: YOUNGSTOWN-WARREN AREA,

delta   azimuth (degrees clockwise from north)
(deg)      eq-to-station     station-to-eq
1.06          236.2              55.4

travel   arrival time
#  code      time(s)  dy hr mn sec
1  Pg          20.39   0 20  5 18
2  sPg         20.92   0 20  5 18
3  Pb          21.09   0 20  5 19
4  pPb         21.44   0 20  5 19
5  sPb         21.83   0 20  5 19
6  Pn          21.88   0 20  5 19
7  pPn         22.41   0 20  5 20
8  sPn         22.74   0 20  5 20
9  Sg          35.19   0 20  5 33
10  Sb          36.46   0 20  5 34
11  sSb         37.05   0 20  5 35
12  Sn          38.13   0 20  5 36
13  sSn         39.00   0 20  5 37
14  PcP        510.96   0 20 13 28
15  ScP        722.84   0 20 17  0
16  PcS        723.12   0 20 17  1
17  ScS        935.02   0 20 20 33
18  PKiKP      994.23   0 20 21 32
19  pPKiKP     994.99   0 20 21 32
20  sPKiKP     995.27   0 20 21 33
21  SKiKP     1206.10   0 20 25  4
22  PKKPdf    1917.27   0 20 36 55
23  SKKPdf    2129.14   0 20 40 27
24  PKKSdf    2129.42   0 20 40 27
25  SKKSdf    2341.29   0 20 43 59
26  P'P'df    2428.55   0 20 45 26
27  S'S'df    3276.86   0 20 59 34

Postscript:

Several people have asked me about the triggering of earthquakes by hydraulic fracturing and waste injection wells.  The USGS has a FAQ page on the subject.

Two Oklahoma Earthquakes

I was busy yesterday and had missed the earthquake activity in Oklahoma.  The Magnitude 5.6 event early this morning (UTC) shown in the bottom of the display,  was large enough to trigger a notification to me from the USGS but the others were below the threshold that I had set.  When I looked this morning I had also picked up the Mag 4.7 at 7:12:45 UTC shown toward the top of the display.  The display shows the relative difference in the size of the waveform for two earthquakes at the same distance but with a 0.9 difference in magnitude.  The larger earthquake released 22.4 times as much energy as the smaller one and should be about 7.9 times bigger on the seismograph.

Magnitude 5.6 – OKLAHOMA

A moderate Magnitude 5.6 earthquake struck Oklahoma at 3:53:10 UTC on Sunday November 5, 2011.  The display shows the waveform received in northeastern Ohio.  The waveform structure for earthquakes this close is complicated and since we don’t often see them I haven’t spent a lot of time trying to decipher it.  The simple body and surface waves are not even listed in the USGS arrival time list shown below:

 DATE-(UTC)-TIME    LAT    LON     DEPTH MAG   Q   COMMENTS
  2011/11/06 03:53:10  35.54N  96.75W   5.0 5.6      US: OKLAHOMA
   Expected 1s period body wave amplitude     [  3.92E-02 µm]  [  2.47E-01 µm/s]

 delta   azimuth (degrees clockwise from north)
 (deg)      eq-to-station     station-to-eq
 12.74           62.4             251.6

                 travel   arrival time
    #  code      time(s)  dy hr mn sec
    1  Pn         181.74   0  3 56 11
    2  pPn        182.95   0  3 56 12
    3  sPn        183.70   0  3 56 13
    4  PnPn       189.55   0  3 56 19
    5  PbPb       223.00   0  3 56 52
    6  PgPg       244.02   0  3 57 14
    7  Sn         325.16   0  3 58 35
    8  sSn        327.17   0  3 58 37
    9  SnSn       338.39   0  3 58 48
   10  SbSb       386.32   0  3 59 36
   11  SgSg       421.22   0  4  0 11
   12  PcP        518.14   0  4  1 48
   13  ScP        731.92   0  4  5 21
   14  PcS        732.55   0  4  5 22
   15  ScS        948.32   0  4  8 58
   16  PKiKP      995.55   0  4  9 45
   17  pPKiKP     997.27   0  4  9 47
   18  sPKiKP     997.90   0  4  9 47
   19  SKiKP     1207.17   0  4 13 17
   20  PKKPdf    1914.90   0  4 25  4
   21  SKKPdf    2126.52   0  4 28 36
   22  PKKSdf    2127.15   0  4 28 37
   23  SKKSdf    2338.76   0  4 32  8
   24  P'P'df    2425.57   0  4 33 35
   25  P'P'ab    2599.91   0  4 36 29
   26  S'S'df    3274.10   0  4 47 44