Paleotsunami data along the California coast are rare and the data that do exist are limited to northern California. For a better understanding of the tsunami threat throughout central and southern California, prehistoric data need to be unearthed and documented in these regions. To accomplish this, the USGS Multi-Hazards Demonstration Project (MHDP) has brought together scientists from the USGS, California Geological Survey (CGS), Humboldt State University, and California State University, Fullerton, to identify traces and develop a prehistoric tsunami inundation chronology. These data will provide geologic evidence to support the next MHDP scenario, which will consider the effect on California of a tsunami generated by a major earthquake in the eastern Aleutian Islands.

Research sites were determined by reviewing previous paleotsunami reconnaissance and research studies, considering coastal geomorphology and historic site-disturbance, and use of tsunami run-up data from the latest numerical tsunami models. These models were developed collaboratively by the CGS, California Emergency Management Agency, and the Tsunami Research Center at the University of Southern California. In response to a major earthquake in the eastern Aleutian Islands, one scenario results in wave elevations in excess of 9 m at some locations along the central and northern California coast, and 4 m in portions of southern California. In late July 2011, reconnaissance fieldwork commenced in northern California south of Point Arena and will continue southward along California’s coast throughout 2011.

Results of the paleotsunami reconnaissance will set the stage for more in-depth research, which will get underway in early 2012. The final results of the study will be used by the State to better assess its tsunami hazard, especially for probabilistic tsunami hazard assessment, and incorporated by the MHDP into the next scenario.

Collaborating scientists and institutions: Graehl, N. (HSU), Hemphill-Haley, E. (HSU), Hoirup, D. (CDWR), Jaffe, B. (USGS), Kelsey, H. (HSU), Kirby, M. (CSUF), Leeper, R. (USGS/CSUF), Peters, R. (Santa Cruz, CA), Rhodes, B. (CSUF), Richmond, B. (USGS), and Wilson, R. (CGS)

What exactly are we looking for during our reconnaissance?

Paleotsunami deposit identifiers:

1. Anomalous coarse-grained material overlying peat or mud: usually composed of sand or coarse silt and may contain gravel.

2. Deposit geometry: laterally continuous or semi-continuous, i.e., mappable deposits that thin landward and away from channels.

3. Provenance: deposits containing sediment consistent with a seaward source.

4. Evidence for event-driven deposition: sharp or erosional basal contacts are characteristic of tsunami deposits. Lack of a sharp basal contact is evidence for gradual change in depositional environment.

Reconnaissance team heading into the field (no. California, 7/11) Photo: Robert Leeper

Sediment-loving geologists (no. California, 7/11) Photo: Robert Leeper

Describing core stratigraphy (no. California, 7/11) Photo: Robert Leeper

Describing core stratigraphy (no. California, 7/11) Photo: Adam Piestrzeniewicz

Identifiers that may be evident in sediment cores:

1. Evidence for turbulent flow: deposits displaying erosional basal contacts or containing rip-up clasts. In narrow-diameter gouge cores, rip-up clasts may be difficult to discern except in thicker tsunami deposits.

2. Evidence for multiple waves (multistage deposit): could include 2 or more coarse-grained beds separated by capping mud or debris.

3. Normal grading: normal grading is common in tsunami deposits.

4. Relatively isolated occurrence: sand deposits in a stratigraphic section, i.e., stratigraphic section not containing numerous other sandy deposits indicating frequent flooding by other means.

Variability in paleotsunami deposit preservation and characteristics:

Depositional environment, geomorphic processes, and historic site-disturbance control how well paleotsunami deposits are preserved. Diffuse, abrupt, irregular contacts and lateral continuity may or may not be seen in paleotsunami deposits.

Below are photos of what we’ve seen in different depositional environments:

California’s coastline (estuaries/marshes):

Tidal channel (no. California, 7/11) Photo: Robert Leeper

Laminated mud atop sand deposit with abrupt basal contact (no. California, 7/11) Photo: Robert Leeper

Bioturbated tidal channel cut bank exposure (no. California, 7/11) Photo: Robert Leeper

Apparent normal grading atop abrupt, irregular contact (no. California, 7/11) Photo: Robert Leeper

Tidal channel cross-bedding atop fire debris (no. California, 7/11) Photo: Robert Leeper

Thailand (swales/depressions):

Abrupt basal contact of 2004 Indian Ocean tsunami (KPT, Thailand, 3/10) Photo: Robert Leeper

Diffuse, irregular contacts and laterally continuous deposits (KPT, Thailand, 3/11) Photo Credit: Ton Sumet

• 

  Abrupt contact and laterally continuous paleotsunami deposits (KPT, Thailand, 3/10) Photo: Robert Leeper

Diffuse paleotsunami contacts (KPT, Thailand, 3/11) Photo: Ton Sumet

This week, the US Navy tested their disaster plans during their annual Citadel Rumble exercise using the USGS ARkStorm Scenario as the basis for the drill. The Navy Regional Operations Center in San Diego served as the basis for where they are conducting a full-scale exercise and is shown in the photo where ARkStorm inundation maps are on their screens. The exercise is focused entirely on the ARkStorm scenario, a month-long winter storm and flooding event, except for an earthquake and volcanic eruption in Washington state that was created only to keep any mutual aid from Pacific Northwest from occurring.

And this isn’t just about moving ships and aircraft to safety. One group, for instance, is exercising plans to address the flooding at Seal Beach with a focus on massive sewage concerns and moving children from their flooded Child Development Centers.

This exercise is just one example of the ways that the USGS Multi Hazard scenarios are used, as designed, by emergency managers and policy makers to prepare for what could realistically occur.

A PDF of the Natural Hazards paper can be found at http://www.springerlink.com/content/j111348544848467/fulltext.pdf

A new report was released on June 20, 2011 by the U.S. Bureau of Labor Statistics (BLS) that estimates the exposure to employers, employees, and payrolls if a large earthquake occurs on the southern San Andrea Fault, which runs through the heavily populated L.A., Riverside, and San Bernardino counties.

According to Regional Commissioner Richard J. Holden, “Themost intense shaking from a Magnitude 7.8 earthquake on the southern San Andreas Fault could affect 434,000 businesses, more than 4.5 million employees of those businesses, with combined annual payrolls of $206.5 billion.”

The counties most affected would be L.A., Orange, Riverside, and San Bernardino. The most intense shaking in L.A., Orange, and Riverside would affect approximately three of every four employees in those counties; in San Bernardino, approximately 96 percent of employees would be affected.

The Regional Report entitled “Labor market risks of a magnitude 7.8 earthquake in California” released today was authored by Regional Commissioner Holden and BLS economists Amar Mann and Tian Luo, who work in the Bureau’s San Francisco office. The authors used seismic shaking information and detailed data on businesses, employment, and wages from the Quarterly Census of Employment and Wages (QCEW) program in BLS to produce the estimates in the report. The QCEW is based on employment tax records collected by state unemployment insurance programs.

Estimated shaking intensities were provided by the United States Geological Survey (USGS) and originally developed in the USGS ShakeOut Scenario. According to USGS, the most likely source of a large earthquake in California is the southern segment of the San Andreas Fault.

“The Bureau of Labor Statistics’ report builds upon the work of the ShakeOut Scenario and puts real numbers to the risk businesses face in the most seriously affected areas of a great San Andreas earthquake on the southern section of the fault,” said Dr. Lucy Jones, Chief Scientist of the USGS Multi Hazards Project which coordinated the ShakeOut Scenario in 2008.

The estimated exposures for Southern California employees in health care (522,000), retail trade (504,000), manufacturing (480,000), and educational services (409,000) were the highest among all industries according to the report. Moreover, 72 percent of health care workers are in the most intense shaking zones. The results of this report
serve as a reminder to public officials, employers, and residents of the vital importance of taking preventive actions to mitigate the potential losses from an earthquake and to prepare for the anticipated disruption to businesses and employees.

President and CEO of the L.A. area chamber Gary Toebben said “In Los Angeles, we are particularly vulnerable, and with so many people and businesses located in this area, the potential economic impact is substantial. Unfortunately, we cannot prevent earthquakes, but we can mitigate the damages by preparing for them. Hopefully, after hearing this report, more people will be motivated to prepare by putting emergency procedures in place.”

The entire report is available on the BLS website at: http://www.bls.gov/opub/regional_reports/southernca/201106_southernca.pdf

Damaged Building in Concepcion, Chile

In July 2010, in an effort to reduce future catastrophic natural disaster losses for California, the American Red Cross coordinated and sent a delegation of 20 multidisciplinary experts on earthquake response and recovery to Chile, including Dr. Lucy Jones, Chief Scientist of the USGS Multi Hazards Project. The primary goal was to understand how the Chilean society and relevant organizations responded to the magnitude 8.8 Maule earthquake that struck the region on February 27, 2010, as well as how an application of these lessons could better prepare California communities, response partners and state emergency partners for a comparable situation. Similarities in building codes, socioeconomic conditions, and broad extent of the strong shaking make the Chilean earthquake a very close analog to the impact of future great earthquakes on California. To withstand and recover from natural and human-caused disasters, it is essential for citizens and communities to work together to anticipate threats, limit effects, and rapidly restore functionality after a crisis.  View the complete report and findings here.

“We must not only strengthen our dams and levees, but we must continue to educate the public, and make consequential decisions, about how to protect ourselves, from such a momentous storm. It is my hope that your studies and report will drive that discussion.”

Read her full remarks here.

The “ARkStorm Scenario,” prepared by the U.S. Geological Survey and released at the ARkStorm Summit in Sacramento on Jan. 13 – 14, combines prehistoric geologic flood history in California with modern flood mapping and climate-change projections to produce a hypothetical, but plausible, scenario aimed at preparing the emergency response community for this type of hazard.

The USGS, the Federal Emergency Management Agency and the California Emergency Management Agency convened the two-day summit to engage stakeholders from across California to take action as a result of the scenario’s findings, which were developed over the last two years by more than 100 scientists and experts.

“The ARkStorm scenario is a complete picture of what that storm would do to the social and economic systems of California,” said Lucy Jones, chief scientist of the USGS Multi-Hazards Demonstration Project and architect of ARkStorm. “We think this event happens once every 100 or 200 years or so, which puts it in the same category as our big San Andreas earthquakes. The ARkStorm is essentially two historic storms (January 1969 and February 1986) put back to back in a scientifically plausible way. The model is not an extremely extreme event.” Jones noted that the largest damages would come from flooding — the models estimate that almost one-fourth of the houses in California would experience some flood damage from this storm.

“The time to begin taking action is now, before a devastating natural hazard event occurs,” said USGS Director, Marcia McNutt. “This scenario demonstrates firsthand how science can be the foundation to help build safer communities. The ARkStorm scenario is a scientifically vetted tool that emergency responders, elected officials and the general public can use to plan for a major catastrophic event to help prevent a hazard from becoming a disaster.”

To define impacts of the ARkStorm, the USGS, in partnership with the California Geological Survey, created the first statewide landslide susceptibility maps for California that are the most detailed landslide susceptibility maps ever created. The project also resulted in the first physics-based coastal storm modeling system for analyzing severe storm impacts (predicting wave height and coastal erosion) under present-day scenarios and under various climate-change and sea-level-rise scenarios. Because the scenario raised serious questions about existing national, state and local disaster policy and emergency management systems, ARkStorm became the theme of the 2010 Extreme Precipitation Symposium at U.C. Davis John Muir Institute of the Environment, attracting over 200 leaders in meteorology and flood management. ARkStorm is part of the efforts to create a National Real-Time Flood Mapping initiative to improve flood management nationwide. ARkStorm also provided a platform for emergency managers, meteorologists and hydrologists to work together to develop a scaling system for west coast storms.

“Cal EMA is proud to partner with the USGS in this important work to protect California from disasters,” said Cal EMA Acting Secretary Mike Dayton.  “In order to have the most efficient and effective plans and response capabilities, we have to have the proper science to base it on. Californians are better protected because of the scientific efforts of the United States Geological Survey.”

According to FEMA Region IX Director, Nancy Ward, “The ARkStorm report will prove to be another invaluable tool in engaging the whole of our community in addressing flood emergencies in California. It is entirely possible that flood control infrastructure and mitigation efforts could be overwhelmed by the USGS ARkStorm scenario, and the report suggests ways forward to limit the damage that is sure to result.”

The two-day summit included professional flood managers, emergency mangers, first responders, business continuity managers, forecasters, hydrologists and decision makers. Many of the scientists responsible for coordinating the ARkStorm scenario presented the science behind the scenario, including meteorology, forecasting, flood modeling, landslides and physical and economic impacts.

The ARkStorm Scenario is the second scenario from the USGS Multi-Hazards Demonstration Project led by Jones, which earlier created the ShakeOut earthquake scenario. The ARkStorm Scenario, USGS Open-File Report 2010-1312, can be found online here.

Pasadena City College student, Ryan Santos, volunteered with the USGS this summer, assisting with post Station fire debris flow research in the San Gabriel Mountains.  Ryan made a huge contribution during his first day in the field by locating a buried monitoring device thought to be destroyed during a debris flow last winter.  He helped conduct water infiltration tests along the ridge of four watersheds being studied by the USGS.  The data collected during these tests will help scientists better understand the connection between rainfall on post-fire soil and the occurrence of debris flows.

When Ryan was asked what he liked most about his fieldwork experience with the USGS this summer, he responded, “I was able to go and see places where not a lot of people can go, and I saw firsthand the way the USGS records and monitors debris flows”.

PCC student, Ryan Santos, records water infiltration test data while on a denuded slope above Big Tujunga Canyon.

PCC student, Ryan Santos, prepares for water infiltration tests along a ridge in Arroyo Seco.

Dawn MacCarthy came to the USGS as a Pasadena City College student taking the course “Natural Disasters”, taught by Multi-Hazards staff scientist Sue Perry.  This fall Dawn transfers to University of California, Los Angeles, where she expects to pursue her previous interest in English, along with a newfound interest in disaster sociology.

efforts for the 2008 earthquake drill ShakeOut received a prestigious federal award Wednesday at the U.S. Geological Survey’s facilities here.

ShakeOut community partners: (left to right) Dale Cox, USGS Multi-hazards Project manager, John Bwarie, City of Los Angeles, Monica Buchanan, State Farm Insurance, Kate Long, California Emergency Management Agency, Anne Kinsinger, USGS Western Regional Director, Lucy Jones, USGS Multi-hazards Project Chief, Margaret Vinci, California Institute of Technology, Connie Lackey, Providence Health and Services.

The USGS Eugene M. Shoemaker Awards for Communications Excellence are given annually to recognize extraordinary effectiveness in communicating complex scientific concepts and discoveries into words and pictures that capture the interest and imagination of the American public.

The 2009 award in the multiple-product category was awarded to The Great Southern California ShakeOut Campaign. Working with an initial committee of 12 people, the group superbly planned and executed a multimedia communication approach resulting in the drill being the largest of its kind in U.S. history, with more than 5 million people participating.

The scenario, written by USGS earthquake experts, called for a magnitude 7.8 earthquake to hit Southern

California along the San Andreas fault. While USGS provided the scenario, the Earthquake Country Alliance brought together many local organizations to create the idea, the promotion, and the execution of the ShakeOut drill on November 13, 2008.

The drill was so successful it has become an annual event, with 6.9 million people participating in 2009. The next iteration will take place Oct. 21, 2010.

Those recognized for communication excellence in the first ShakeOut are:

Earthquake Country Alliance community partners:

ShakeOut community partners: (left to right)
Dale Cox, USGS Multi-hazards Project Manager, John Bwarie, City of Los Angeles, Monica Buchanan, State Farm Insurance, Kate Long, California Emergency Management Agency, Anne Kinsinger, USGS Western Regional Director, Lucy Jones, USGS Multi-hazards Chief Scientist, Margaret Vinci, California Institute of Technology, Connie Lackey, Providence Health and Services. (high resolution image)
City of Los Angeles, John Bwarie
State Farm Insurance, Monica Buchanan
California Emergency Management Agency, Kate Long
Southern California Earthquake Center, Mark Benthien
California Institute of Technology, Margaret Vinci
Art Center College of Design, Sohini Sinha
Pearce Global Partners, Ines Pearce
LA County Fire Department, Larry Collins
CBS Radio, Jack Popejoy
U.S. Geological Survey employees:

Multi-Hazards Demonstration Project

Lucy Jones
Dale Cox
Sue Perry
Earthquake Science Center

Ken Hudnut
Erik Pounders
Menlo Park Publishing Service Center

Peter Stauffer
James W. Hendley II
Judy Weathers
Office of Communications

Stephanie Hanna, retired
Leslie Gordon
Paul Laustsen
The Shoemaker Communications Awards were established in honor of Gene Shoemaker, a USGS astrogeologist who is considered the founder of the science of lunar and planetary geology. He was noted as an effective and prolific communicator as well as an innovative scientist researcher. One of his greatest assets was his ability to communicate scientific concepts to non-scientists in a way that could be easily understood and appreciated.

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