SPECULATIONS ABOUT BEACH EROSION, SEA-LEVEL RISE, STORM SURGE, HURRICANE, EARTHQUAKE, AND TSUNAMI HAZARDS FOR HOMES IN CABO PULMO NATIONAL PARK, EAST CAPE, CALIFORNIA BAJA SUR, MEXICO

Cabo Pulmo National Park is a national marine park on the east coast of Mexico's Baja California Peninsula, approx. 100 km north of Cabo San Lucas, on the Sea of Cortez. In 2014, I met a realtor that had a client interested in buying a home on the beach that wanted to know how sea-level rise might effect the home for sale. The question spurred my curiosity, and I offered to look at the site and provide an estimate of the potential rise, which I thought would be easy, given other workers studies globally. The home is located approx. 80 m north of the National Park headquarters. To my shock, I found the home and several other homes along the beach were built in the intertidal zone, on (or within?) the fore dune beach, roughly at MHWL (or slightly above it when they were built?). Immediately, I thought about tsunami inundation, and later hurricanes and tropical storm surges. I decided to investigate and attempt to quantify the hazards (probability of exceedance in the next 50 years)and wrote a brief report (pro bono publico), which was forwarded to the client and the insurance company. Needless to say, the home is still for sale, and the insurance company asked for more details. My conclusions are that sea-level rise is much less of a hazard than those posed by tropical storm surges and hurricanes, which have recurrence times of a few to several years on and near the Baja Peninsula. The most likely chance of inundation (exceedance) is posed by regional tropical storm surges and near misses. A direct hit from a hurricane has a very low probability but extreme consequences. The “background” events are astronomical tides, where Sun and Moon and other planets align (conjunction or syzygy), especially when Earth is at perihelion. Tsunami height and frequency depend on earthquakes from the San Andreas fault located ~40 km offshore to the east under the Sea of Cortez. Cabo Pulmo is sheltered from regional tsunamis, given it’s location in the Sea of Cortez.