Hazard Roundup--May 2008

Welcome back everyone to the USGS CoreCast. I'm Scott Horvath. Today I'm doing our Hazard Roundup episode for May 2008. Let's get right into it.

May has been a very busy time for earthquakes, but here's some of the more significant ones. There was a 6.6 in Alaska on May 2^nd, near the Andreanof Islands, a 6.8 near the coast of Honshu, Japan on May 7^th, a 6.7 in the Guam Region on May 9^th, and of course...the one that is still in the news and the most discussed is the 7.9 on May 12^th that struck Eastern Sichuan, China. Since the May 12^th there have been about 100 aftershocks through May 29^th all within the range of M4.5 or larger, 40 of them over M5, and 2 over M6. Now although the USGS does not officially deal with death toll information, the Chinese officials are, however, expecting the death toll to raise above 80,000. Based upon the earthquake data, the USGS's PAGER map indicated that 866,000 people were exposed to severe shaking with the potential of moderate to heavy damage to resistant structures and heavy damage to vulnerable structures.

Additionally, as you have probably already read, there is a large lake forming around that same area as a direct result of the earthquake. This is referred to as a landslide-dammed lake, or reservoir. The lake dammed behind the largest of the landslide dams is about 8 miles in length. Currently the Chinese are actively working on creating a spillway that will release the lake waters to be somewhat lower than what it is now. Meanwhile residents of the surrounding lake area are being evacuated just in case.

Over to landslides, on May 22, 2008 a storm that developed over parts of southern California prompted the NWS to issue warnings for flash floods and debris flows from the Santiago Fire in Orange County, and the Poomacha and Witch Fires in San Diego County.  These areas, along with several others,  burned in this fall's firestorm.  Field reconnaissance after the storm revealed damaging debris flows and floods generated from the canyons burned by the Santiago Fire in Orange County.  In Modjeska Canyon, the lower level of one house was filled with approximately 1 m of mud and debris, and several yards and pastures were also inundated.  Roads in the burned area were covered with mud and debris in several locations.  Flooding across State Highway 76 was reported for the Poomacha Fire.  Documentation of the response of the burned basins to the storm, coupled with rainfall measures, will be used to advance the development of models for post fire debris flow susceptibility for southern California.

Related to flooding there was, of course, the events that occurred between the end of April into the beginning of May in Maine. The flooding caused extensive damage to homes, bridges, roads, and more throughout areas of northern, central, and coastal Maine.

Briefly, with wildfires, there was a fire on the east side of Shark Slough in Everglades National Park, called the Mustang Corner Fire, started on May 14^th. It remained within the park and reached about 40,000 acres.

Last, but not least, yesterday, June 1^st, marked the start of hurricane season. Although the National Oceanic and Atmospheric Administration (NOAA) handles all the information and data related to hurricanes and hurricane tracking, the USGS also plays a significant role...and that's through our Coastal and Marine Geology Program for the national assessment of coastal change hazards.  Hurricanes and other extreme storms can generate dangerous waves and currents capable of moving large amounts of sand, destroying buildings and infrastructure, and reshaping our coastlines.  The USGS research focuses on understanding the magnitude and variability of the impacts of hurricanes and extreme storms on the sandy beaches of the United States. The overall objective, of course, is to improve the capability to predict coastal change that results from severe storms.

So, as the hurricane season progresses, you can stay up-to-date on what is occurring by visiting the USGS Natural Hazards Gateway. Just go to usgs.gov and click "Hazards" on the top menu bar. Or you can do directly at usgs.gov/hazards. There you'll find a link to the Hurricane hazards page with more information, latest news releases, and even current hurricane advisories in one location.

That does it for this episode of the USGS CoreCast. As always, thanks for taking the time to listen.

The USGS CoreCast is a product of the U.S. Geological Survey, Department of the Interior. Until next time, I'm Scott Horvath saying "Keep it cool."

Mentioned in this episode:

• USGS PAGER Map for M 7.9 in Eastern Sichuan, China
• Coastal and Marine Geology Program
• Hurricanes and Extreme Storms
• Natural Hazards Gateway

Music Credit:

"A Mastermind's Plan of Evil", Edgen