For the first time in decades — a hurricane hit California. An earthquake followed. Learn about this natural phenomenon and how it's linked to climate change.
Imagine preparing for a hurricane, and then getting hit with an earthquake. This is what happened to the residents of Southern California on August 20, 2023 — for the first time in history. The last time a tropical storm hit California was 1939. This tropical storm never reached the 119 kilometers per hour (74 mph) windspeed requirement for hurricane designation while over land. But the recent storm did briefly meet this requirement before landfall.
Why doesn't California usually get hurricanes if it's a coastal state?
Unlike the Caribbean and the Atlantic Ocean, which are prone to hurricanes due to warm water currents and the Gulf Stream; the Pacific ocean’s typically cold water prevents tropical storms and hurricanes from forming. Waters must be 26 degrees Celsius (79 degrees Fahrenheit) in order for a tropical storm to form. The Pacific coast of California gets streams of cold water originating near Alaska, chilling the waters and making them inhospitable to hurricanes. California also has an east-to-west wind pattern; making it challenging for storms to actually hit land. They're usually pushed back into the Pacific ocean.
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The storm caused the Los Angeles region to get 13.7 centimeters (5.3 inches) of rain over 24 hours. The area with the most rainfall from tropical storm Hillary was Mount Wilson — which received 30 centimeters (12 inches, or one foot) of rain. These areas are not structurally designed to withstand the impact of flooding and winds; unlike hurricane prone areas, such as Florida, placing the people who live in these regions in peril.
While dealing with the impact of the tropical storm, Californians received a second unwelcome surprise: a magnitude 5.1 hurricane impacting areas in and around Ojai. Fortunately, the damage caused by the earthquake was insignificant — it was mostly a shock. This is the first time an earthquake of this magnitude has hit this area since 1941, and the first time a “hurriquake” has occurred.
What could’ve caused the hurricane?
The simple answer? Climate change. The oceans were reported to have the highest temperature in 174 years, according to the National Oceanic and Atmospheric Administration (NOAA). The NOAA confirmed that ocean temperatures on the coast of California have been specifically impacted by this change. In April, it was reported that the ocean temperatures reached 21.1 degrees Celsius (70 degrees Fahrenheit) — 0.1 degree higher than the previous record. The NOAA suspects that the continued use of fossil fuels, and the global trend of increased temperature on both land and sea have contributed to the creation of Hurricane Hillary off the coast of California.
Is the hurricane linked to the earthquake?
The “hurriquake" might not just be a coincidence — the low pressure caused by hurricanes have actually been found to create earthquakes. In 2018, Assistant Professor Wenyan Fan at Florida State University accidentally realized while reviewing weather data, that there is a correlation between storms and seismic activity. Typically, the low pressure will cause minimal seismic shifts, but there is the potential to cause full-scale earthquakes. This phenomenon is still being studied; so time will tell if the “hurriquake” was caused by the pressure shifts from the storm.
Climate change is increasing the frequency and changing the location of natural disasters like hurricanes — leaving communities unprepared and at risk of devastation. Although we cannot control the weather, we can do our part to help organizations that are working to mitigate the effects of climate change on our environment.
