EARTHQUAKE SUMMARY FOR SEPTEMBER 26, 2011
The earth was hit today by the strongest geomagnetic storm since December 15, 2006. This combined with the new moon which arrives today at 11:09 UT may bring on active seismic conditions. A major earthquake is considered likely near the geomagnetic equator or at high latitudes in the next six days. We are calling a global seismic watch in association with this geomagnetic storm and tidal event.
GEOMAGNETIC STORM
The geomagnetic field was at storm conditions today. The AP level was 67. The high latitude AP was about 51. The KP level reached 8-9 late in the day, the most disturbed field disturbance in months. The storm was the most intensities since the AP level reached 104 on December 15, 2006 nearly five years ago. SWPC expects storm to active conditions in the geomagnetic field through the next three days with active but declining solar activity. A global seismic watch is currently in effect for the period September 27-October 3. The largest earthquakes are expected to be 20-25% higher than previously estimated during this period. Seismicity will be enhanced, for the most part, at 10-15 degrees from the geomagnetic equator and at high auroral latitudes. Other areas where seismicity is expected to be active is in zones of high heat flow and volcanism and in mountainous regions.
TIDAL EFFECTS
September 27, 2011 is the first day of the new lunar month (new moon). The new moon will arrive at 11:09 UT today. The areas most likely to see increases in tidally triggered seismicity will be within about 20 degrees longitude of 165W and 15E. This includes regions of the Tonga-Fiji to Kermadec Islands, the western Aleutians and Andreanof and Fox Islands and central and eastern Europe. The largest earthquake at the last new moon was an M 6.8 in the Banda Sea but unusual earthquakes in the North Atlantic and the Puerto Rico to Leeward Islands region indicated some increased tidal triggering in that region as well. Generally, seismicity in subduction zones and other regions where seismicity is dominated as occurring between layers of the earth's curst increases during the several days around the full moon.
http://www.earthquakesummary.info/Just before 12:00 UTC Monday, the ACE Spacecraft detected a solar wind increase from 350 km/s to over 700 km/s at its peak. This indicated the arrival of a the Coronal Mass Ejection (CME) sweeping past the spacecraft which was the result of a long duration M7.1 Solar Flare on Sept. 24. The Bz had titled sharply south at times (-30nT) and a Strong G3 to G4 Level Geomagnetic Storm occurred at high latitudes. Less severe Geomagnetic Storming took place at middle latitudes. Because the timing of the CME shock was early in the day, visible Aurora would have favored Europe and not here in North America. The Kp did decrease to 4, however storm conditions did flare up again for a short period. With the solar wind still gusting near 700 km/s, expect minor conditions to persist throughout the night.
Many Aurora contacts were made on the 2m (144mhz) and 6m (50mhz) amateur radio bands in both Northern Europe and Northern parts of Canada and USA.
EXTENDED WARNING: Geomagnetic K-index of 5 expected
Valid From: 2011 Sep 26 1250 UTC
Now Valid Until: 2011 Sep 27 0900 UTC
Warning Condition: Persistence
Geophysical Activity Summary 25/2100Z to 26/2100Z:
The geomagnetic field has been at major storm levels for the past 24
hours. A CME, observed leaving the solar disk on 24 September,
arrived at Earth on 26/1237Z. Indicating the arrival of the CME, a
45 nT sudden impulse was observed by the Boulder magnetometer. As
the CME progressed, measurements by the ACE spacecraft showed the
total IMF reaching a peak of 33 nT, with the negative (Southward
Component, Bz) reaching a maximum of-31 nT. Solar wind speeds
increased from around 350 km/s to 650 km/s. During the CME passage,
both GOES 13 and GOES 15 spacecraft showed clear magnetopause
crossings. The greater than 10 MeV proton event, that began at
23/2255Z, reached up to 35.7 pfu at 26/1115Z, and continues to
remain above the 10 pfu threshold.
Geophysical Activity Forecast:
The geomagnetic field is
expected to be at unsettled to active levels for the next two days
(27-28 September) with a slight chance for minor storm levels, due
to the trailing effects of the latest CME and the possible arrival
of a second CME. A return to predominately quiet levels is expected
on day three (29 September).
http://www.solarham.com/swpc.htm
