For those unclear on what this is about.... like me.

 Yuri - do you know if Mexico is planning to invoke the International Charter?

Sandwell and Fialko are coordinating a GPS campaign (possibly tomorrow, Apr. 5). A number of benchmarks were installed last month in the Cerro Prieto area. We also plan to occupy the nearby SCEC CMM benchmarks. 

Also, the epicentral area is pretty arid. InSAR should work well (now that the hypocentral depth was revised from 30 to 10 km). We are going to ask space agencies to provide near-real time SAR through WInSAR. 

I tried email to Alejandro Nava as well - no word back.

Thanks for the updates.  This event sure makes the case for closer cross-border collaboration.  I haven't yet reached Jim or Sue.  Xyoli replied though.  She got a phone call from Carlos Valdes (current head of SSN) who is on his way to the SSN. FWIW, he told her that their station in Mexicali went out 7 minutes after the earthquake hit.

Javier Gonzàlez-Garcìa (CICESE) attended the last SCEC Annual Meeting - has worked with Hudnut. Try contacting him: javier@cicese.mx

Shaking lasted about 40 secs in Encinitas.  Poll sloshed over the edge.   Tried to call Rockwell and left a message.  I see the magnitude just got updated.  How about the location?

I am trying to get in contact with Tom Rockwell about organizing a field response. It seems to early to tell right now even what fault this may be (Cerro Prieto? Laguna Salada?). Is there a focal mechanism? Can't find one at USGS site yet.

Yesterday during the tabletop discussions, and in several meetings leading up to that, we were able to have a few key things clarified about roles and expectations.

Jerry Treiman of CGS and Katherine Kendrick of USGS were involved in these discussions, as was Ralph Loyd of CGS, Kate Long of Cal EMA, and Steve Walter at USGS Menlo Park among others.

We recognized that there is the immediate need for a coarse yet synoptic overview of the rupture that is of immediate use in, for example, notifying emergency management about the likely locus or quasi-linear distribution of disruption to critical lifeline infrastructure and also for us to modify, update and correct the ShakeMap using info on the finite fault source.

For the Situation Unit we will not be setting up to handle detailed surface faulting data, such as curvilinear line work in a GIS system. Our data handling within the minutes to hours time frame will be much simpler than that. We hope to get in field reports of GPS position location and observation such as would be reported on the standard form distributed last year by Luke Blair (offset, slip vector info).

In addition, and in a later time frame, the Clearinghouse will 'stand up' and will be geared towards taking in and compiling surface fault rupture data including rupture mapping line work. It may be more like 6 hrs., 12 hrs. or even 24 hrs. after the time of the earthquake that this capability will be established at the Clearinghouse, at which point we would make a hand-off and transfer all data from the ICS Situation Unit here to the Clearinghouse.

There are details of this that will still need to be worked out, and this would all be happening during the same time interval that people are establishing the field meeting sites, etc. There is still a need for more discussion to work out this plan, and please count on Jerry, Katherine and me to help share the info from yesterday and the other recent meetings - I think that transfer of info needs to occur soon and that it will be helpful to the overall collective effort. Thanks!

SCENARIO Earthquake Aftershock Probabilities Update

3:00 pm PST

Here are updated aftershock probabilities now that 4 hr. 45 min. have passed since the scenario M 7.8 event: 

This assumes standard (generic) aftershock parameters for Southern California.  The largest aftershock so far occurred at 11:00 am PST, and had a magnitude of 7.0.  Secondary triggering from this aftershock has been included in this current forecast. 

Within the next hour (3:00 pm – 4:00 pm PST) we can expect approximately 11 M ≥ 4 aftershocks, and 1 M ≥ 5 aftershocks.

Within the next 12 hours, we can expect approximately 68 M ≥ 4 aftershocks and 7 M ≥ 5 aftershocks.

The probability, from this time forward, that at least one earthquake larger than M 6 will be triggered is 90%.  The probability that an earthquake larger than M 7 will be triggered is 21%.

The probability, from this time forward, that an earthquake larger than the M 7.8 mainshock will be triggered is 3.6%.  This probability will fall with time if no exceptionally large aftershock occurs.

-Karen Felzer