November 4, 1999; Mammoth Lakes Fire Department Last-minute discussion before the communication exercise on November 4 was launched from Mammoth Lakes, California (from left to right, Marvin Howard, Mammoth Lakes Fire Department; Dave Hill, U.S. Geological Survey; John Linder and Bill Bonshu, State of California Office of Emergency Services). The exercise used a hypothetical eruption from along the Mono-Inyo Craters volcanic chain to test the emergency communication systems and pathways between government agencies and private industry. The eruption scenario was similar to the volcanic activity that occurred in the Long Valley area about 600 years ago. The primary agencies involved were the Town of Mammoth Lakes, City of Bishop, Mono and Inyo counties, Office of Emergency Services, U.S. Forest Service and the U.S. Geological Survey.

	The exercise began when USGS scientist Dave Hill (top) notifed the California Office of Emegency Services that the Long Valley color code had changed from GREEN to ORANGE (eruption was likely in the Long Valley area within hours to days). The call was made from the USGS office in the Mammoth Lakes Water District Office (bottom).

In the hypothetical exercise, the change in color code was based on the USGS monitoring networks in the Long Valley area. According to the message delivered by Dave Hill, "intense earthquake and ground-deformation activity currently centered near Wilson Butte along the Inyo Craters, 8 miles north of Mammoth Lakes, indicates that a volume of magma is being injected into the shallow crust with a strong possibility that the magma will reach the surface to produce a volcanic eruption in the coming hours to days." This hypothetical message set in motion hundreds of calls between about two dozen government agencies and private industry during a three hour period.

The exercise ended immediately after the rising magma caused ground cracks in Highway 395, forcing officials to "close" the highway to traffic, and an explosive eruption sent volcanic ash high into the atmosphere.

Exercise participants discuss their principal observations immediately after the 3-hour communications exercise.

Results from the communications exercise will be collected and analyzed in order to improve the delivery of information during a future emergency (not just from volcanic unrest). The exercise was considered a success because (1) emergency notices were delivered quickly according to existing emergency plans; (2) the notices were delivered using multiple pathways, including telephone, faxes, radio, and satellite transmissions; (3) outdated telephone numbers and contacts were identified and new ones included in various notification lists; and (4) emergency issues related to a potential volcanic eruption in the Long Valley area were considered by all participants.

Additional Long Valley Information

Long Valley Observatory

Home page of the Long Valley Observatory, including links to monitoring data and the current condition of the caldera.

Volcano hazards in Long Valley, California

New description of the principal volcano hazards in the Long Valley area available from the website of the Long Valley Observatory.

Inyo eruptions about 500 years ago

New summary of the series of eruptions that occurred along Inyo Craters volcanic chain, including explosive eruptions, extrusion of lava flows, and faulting of the ground.

Photo Gallery of the Long Valley area, California

New photographs of the geologic features in Long Valley caldera and along the Mono-Inyo Craters volcanic chain.

Color code for the Long Valley area, California

Summary of the color code notification system that is used to provide information about the status of activity in the Long Valley area.