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Winter 1990

Earthquake Response by the SCS




Luana Kiger, area conservation for the central coast, reports that Elton John's song "We're still standing" has taken on new meaning after the October 17 earthquake in the Santa Cruz mountains. Five SCS offices received minor damage in the quake. The primary problems in the first week were power shortages, intermittent to no phones, closed roads, and reduced staff. Some employees' homes were hard hit and it was a week before everyone was back to work. Employees at the Half Moon Bay field office assisted with search and rescue the first few days after the quake.

The damage assessment started the next day. SCSers worked with local county officials to assess damage to levees, irrigation ditches, flood control channels, drop structures. and dams. They also checked for channel blockages. Numerous landslides in the steep mountain terrain blocked roads and tributaries.

Under SCS's Emergency Watershed Protection program, funds are available to assist local sponsors to clean out blocked tributaries when there is a threat to life or public property. Corralitos Creek in Santa Cruz County had three landslides in close proximity that had backed water up a 1000 feet creating ponds 35 feet deep. Twelve homes were directly threatened and another 312 families whose only access was the Eureka Canyon Road paralleling the creek were impacted. The necessary inspections, designs, funding, and permits were put together by Saturday after the quake and removal of the debris started. Throughout the three week construction period, aftershocks kept shaking the area, triggering additional sliding above the project area.

SCS also assisted local farmers and ranchers with checking dams for quake related damage in the ten county area. No damage was reported in the East Bay. On the average, less than ten percent of the dams checked in Santa Clara, San Benito, Monterey, and San Mateo sustained damage. However, in Santa Cruz, approximately forty percent of the dams checked sustained damage. Longitudinal cracks in the fill were the primary damage.

SCS is providing technical assistance consisting of inventory and evaluation, and design if requested, for damaged dams, irrigation systems stockwater systems, and other soil and water conservation measures. Homeowners are being given recommendations on drainage and erosion control, particularly in the landslide areas. Farmers in the strawberry hill area by Elkhorn Slough reported broken connections for irrigation systems and some damage to underground outlets. A number of wells and irrigation mainlines were reported broken in Santa Clara, San Benito, and Monterey counties. Some fields near the Salinas River need to be re-levelled after sand boils appeared during the quake. Levees along the Pajaro and Salinas rivers were damaged and are being repaired by the Corps of Engineers.

The quake started up new springs and closed off old ones. Tributaries that had been dry on the 17th were showing water on the 18th. This effect was most pronounced in the Santa Cruz mountains, but was also reported in San Mateo, Santa Clara, San Benito, and Monterey county nearly 100 miles from the epicenter, dried up immediately.

There are numerous cracks and fissures in the Santa Cruz mountains. Many are associated with large ancient landslides. Everyone is gearing up for more emergency work once the rains begin and the soil becomes saturated. That there was less damage than expected was attributed not only to modern construction standards, but also to the fact that the soil was dry.


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