From Rob Handson's post on the ACS/ARES Groups.io page. Dave AI6VX
From: Hanson, Robert - W6RH w6rh@hotmail.com Date: Tue, Feb 20, 2024 at 11:02 AM Subject: [vc-acs] [VC Situation Update] UPDATE: Advisory to be Distributed to La Conchita Residents
Sheriff’s Emergency Services, in close coordination with the Ventura County Public Works Agency, Ventura County Fire Department, & County Executive Office, regularly monitor conditions in the Community of La Conchita. As of this morning, La Conchita has received 11.48” of rainfall over the course of 30 days. With an additional 1”-2” of rain in the forecast over the next 48 hours, it is possible that La Conchita may reach one of several historical thresholds for causing a landslide.
Following the devastating events in 1995 and 2005, the Community of La Conchita was declared a geological hazard zone by the County of Ventura.
The geologic hazards present in the community include:
1. Landslide and/or debris flows: The large landslide mass located above the community could potentially fail, impacting residences within the community at any time, without warning. 2. Mudflows: Mudflows could impact residences and access roads throughout the La Conchita community.
It is incumbent upon residents who choose to live in the La Conchita community to exercise due diligence in monitoring the condition of the hillside and taking early action to evacuate during periods of increased danger.
The following historical triggers in the La Conchita area help to serve as indicators of a potential geological event:
· 15” of rainfall within a 30-day period.
· 8” of rainfall within a 14-day period.
· ≥ 1” of rainfall in an hour. This threshold is not unique to La Conchita and may trigger flooding, landslides or debris flows at any location.
Due to the complex nature of the hazards present in the Community of La Conchita, public safety personnel have no way to predict if or when a failure of the hillside may occur. Because of this, residents should not wait for local authorities to issue evacuation warnings or orders before leaving the area. It is advisable that residents monitor weather forecasts, rainfall rates and current conditions of the hillside to determine when they need to evacuate.
Additionally, On Sunday 2/19/24, a small slope failure occurred within the 1995 landslide scar. This failure was inspected by the Ventura County Public Works Agency and determined not to be a threat to the community. While this failure is not indicative of a larger looming issue, it does serve as a reminder that the hillside is reaching saturation and the propensity for events is higher than normal.
For these reasons, the attached notice has been approved by all stakeholders to be distributed to La Conchita residents by 12:00PM on 2/20/2024. Additional information will be sent out in English and Spanish via social media, VC Alert and posted on VCEmergency.com.