© Kenny Ryan, UC RiversideMap of regional peak tsunami amplitude in meters resulting from an earthquake on the Pitas Point and Lower Red Mountain fault system. The thin solid black line indicates the coastline and the thick black line indicates the Pitas Point fault trace.
Californians may be used to hearing about the threat of potentially deadly earthquakes,
but a new study finds that quake-triggered tsunamis pose a greater risk to Southern California than previously thought.Tsunamis are monster waves that can reach more than 100 feet (30 meters) high. They are often caused by earthquakes; the
2004 Banda Aceh earthquake and tsunami killed about 250,000 people, while the 2011 Tohoku earthquake and tsunami that struck offshore of Japan killed about 20,000 people and
triggered a nuclear disaster.
Tsunamis increase in size as the depth of water in which they occur decreases. Since water depth is usually shallow near coastlines, tsunamis can grow as they approach land, becoming particularly dangerous along heavily populated coastlines, such as those in Southern California, the researchers said.
Scientists focused on the Ventura Basin in Southern California, which has offshore faults that can probably generate earthquakes of magnitude 7 or greater.
The researchers created 3D models of ruptures on the 31-mile-long (45 kilometers) Pitas Point and 22-mile-long (35 km) Lower Red Mountain undersea faults.
Although homes and buildings on the coastlines directly opposite these faults would naturally be vulnerable to any tsunamis, until now, additional low-lying areas farther to the east were not necessarily expected to be in harm's way. The new study suggests the cities of Ventura and Oxnard might be under
greater threat of tsunami flooding than was previously thought.
