Hi All,

Our day today at the AGU was quite interesting. We started late morning in sitting in on a Geodesy session covering Crustal Rotation at Diffuse Plate Boundaries. This topic covers movement of blocks and the directions they travel. For instance, at the Center of the Andes there is a split where the northern end moves counter-clockwise and the southern portion moves clockwise. This type of event occurs in many places on the planet including the northern Walker Lane belt, which one day will travel to the area of Medicine Lake, Lakeview, Oregon and may arrive where Eugene, Oregon is today. It is also felt that it may encompass all of the Cascades in the future (millions of years).

During the lunch break, after that session, literally thousands of AGU attendees were treated to a street demonstration by a man who felt that geoscientists were not following God's law and through much dissertation, which at times was humorous, he asked them to set aside their microscopes and seek another avenue of employment. He seemed to be dressed in something I would call a "rent-a-priest" costume. We hung out for at least 30 minutes to catch the performance and the group interaction was well worthy of viewing.

After the lunch break we enjoyed perusing many of the posters in the Seismology section. Two we found more interesting than the others. One provided an answer as to why the aftershock pattern following the San Simeon quake was not in a straight line as one usually sees, but it said that due to synclines it created a block. One of the diagrams on the poster it indicated there was a 5.7 earthquake off shore, SW of Cambria in 1906, which we found interesting. (See link below for S41A-0924)

The next was a poster on Non-Planer faults, focusing on the 1891 Nobi, Japan quake. It pointed out that faults which have branches, such as those seen at Parkfield for instance can have earthquakes in which the primary fault as well as part of the branch can both be activated during one single earthquake. The branches in time from these types of events will become curved, rather than remaining straight. If you examine the Parkfield segment of the SAF on the USGS map you'll see the branches quite clearly. (See link below for S41A-0948)

Tomorrow is the Big Session on Parkfield. It's a wall to wall, all day event, with so many of the scientists providing information on what they learned about the 6.0 Parkfield earthquake. While I am enjoying my company Christmas party in SF, Don will sit in and I plan on joining him late in the day and at least catch the last session of the day.

Petra

http://www.agu.org/meetings/fm04/fm04-sessions/fm04_S41A.html

• AGU Poster Abstracts