Scientific Motivation

The majority of effort in post-earthquake geologic response will center on detailed mapping and measurement of the ground rupture. These maps are fundamental to understanding the earthquake rupture and for corroborating investigations of fault slip from seismic and geodetic data. Previous mapping of historic ruptures has had lasting impact on understanding earthquake phenomena, such as the width of damage zones and the role of step-overs in nucleating or arresting rupture. For a rupture in southern California, field mapping will also complement analysis of before- and after-lidar imagery. The overall mapping effort will take place over several weeks after the earthquake. However, there is extra merit to rapid assessment of the ground rupture (within the first 24-48 hours) for planning geophysical experiments, imagery acquisition, and for assessing damage to lifelines. Because many SCEC geologists are situated within or near to southern California, SCEC is well positioned to coordinate such a rapid assessment.

Agency Roles

In the case of a ground-rupturing event in southern California the Pasadena office of the USGS is expected to take the lead in compiling the mapping effort. In turn it is expected that the USGS will readily share the compiled results with the research community in real time, as these are collected. Rapid post-rupture assessment will be most efficient if SCEC geology works closely with the USGS for data assimilation and communication.

It is also anticipated that the CGS will deploy its geologists to the rupture site. The CGS will also likely take the lead at establishing an earthquake information clearinghouse. The role of the clearinghouse is to coordinate all field data collection efforts (geologic mapping, site effects such as liquefaction, and engineering) such that resources are used most efficiently. The clearinghouse also works to pass on useful information to the office of emergency services (OES). An important role of the clearinghouse is to direct researchers that come from 'outside.' This includes academic scientists not affiliated with SCEC or its peers in engineering (e.g. EERI) and geologists/engineers from industry that wish to participate in the data collection effort.

The USGS is a partner in setting up the clearinghouse. However there appears to be some overlap between the role of the clearinghouse and the anticipated role of the Pasadena USGS office. At this time it appears that the most efficient division of labor is to have the Pasadena USGS take the lead in the aggregation of geologic data from the field and then pass on the aggregated data to the clearinghouse. This way rapid post-earthquake observations will be disseminated to the OES in an orderly manner with maximum impact for damage assessment to lifelines. Though outside the realm of science planning, it is worth keeping in mind that many of the lasting economic impacts of a major earthquake arise due to damage to transportation and resource lifelines.

It would be beneficial to establish a two-way exchange of data with the clearinghouse. They will be independently gathering information from 'outside' researchers and they will have access to imagery data from other sources, such as the California National Guard, that the USGS and SCEC researchers may find useful.

Field Logistics

Planning for post-earthquake geology response is fraught with uncertainty. It is impossible to anticipate ahead of time the location and extent of a surface rupture. Nor is it possible to predict how readily SCEC scientists will be able to access the field. Some researchers will come from unaffected areas such as northern California or neighboring states. In the event of a major earthquake on the San Andreas fault these outside researchers may be the first to reach the rupture on the ground. Smaller events will be easier for local SCEC scientists to access. Rapid assessment of the rupture requires efficient communication. Ground and cellular communication lines will likely be crowded and could very well be inoperative. At the present time few SCEC geologists have access to satellite telephones.

To enable rapid assessment of the earthquake rupture we propose the following roles within SCEC geology:

1. Field Communication Coordinator. This person will be responsible for meeting with SCEC geologists at a designated site in the field to gather results and transmit this data to the USGS Pasadena office. This role will be subsumed within the USGS field campaign as soon as it is operative. In most cases this will happen on the day of the earthquake and the coordinator's role will be advisory. Even so, the coordinator will have an important role in advocating SCEC needs to the larger USGS effort. The primary coordinator should be a geologist within the urban region. The secondary should be someone outside of the area. Backup people are needed for both positions.
2. Science Lead. Many of the likely surface ruptures in southern California will be on faults associated with a particular SCEC PI. In this case this person should help take the lead in planning the response from the field. The SCEC geology planning committee members will take the lead in identifying this individual and advocating her/his participation in leading the geologic science response.

At the USGS there are three roles with whom SCEC will need to work closely. I have tried to guess how people would fill these roles:

1. The field mapping coordinator (?). This is likely to be Katherine Kendrick
2. A contact person at the USGS for data exchange. Luke Blair is filling this role for the Shakeout event. He is regularly at Menlo, however. At this time it is not clear who this person would be in a real event.
3. The USGS science lead (?). This is likely to be Ken Hudnut, at least for geology and geodesy.

In order to organize SCEC research the following plans and equipment needs to be in place:

1. A DVD with topographic and road base maps for all major southern California faults should be compiled and distributed to the community. This way researchers will not need to scramble to find this base data after an event occurs.
2. Standardized forms for earthquake rupture observations, available from the USGS and CGS, should be made available, both in document format and as forms for input in digital assistants. It might be useful to review this form at the upcoming SCEC annual meeting geology plenary so everyone is familiar with it. A copy of this form should be distributed on the DVD.
3. The field communication coordinators and backups need to have access to satellite phones for use in the field. These numbers need to be shared within the geology community and with the rest of SCEC and the USGS. This may require purchase of phones by SCEC. There is a pressing need to increase our communication capability for field response by SCEC.
4. Field rendezvous points should be planned for ahead of time for each major fault segment that is likely to rupture in southern California (essentially all class 'A' faults and some class 'B' faults). This should be coordinated with likely Science Leads for each fault. This list should be posted online, emailed to the SCEC geology community, and included for distribution on the DVD.
5. A list of all participating SCEC geologists and their cell-phone contact information should be kept and updated regularly. If the cell phone or SMS systems are operative, this will be used to remind SCEC geologists of the locations of field rendezvous points.