Until recently, scientists were puzzled why an earthquake of only 7.5 magnitude caused a devastating tsunami that killed over 2,000 people on the island of Sulawesi in Indonesia in September of 2018. The earthquake didn’t even trigger the tsunami early warning system as normally a tsunami of the size (wave height up to 11m or 36 ft) would require an 8.4 or higher magnitude earthquake. A new study published in the journal Pure and Applied Geophysics has found that the cause of the tsunami was actually a marine landslide in Palu Bay on the west coast of Sulawesi. A combination of computer modeling and observation of the actual sea level data from the event was used to reach their conclusion. They observed a wave period that was very short, consistent with the 3 to 4 minutes expected based on the modeling of a marine landslide compared to the 15 to 60 minute periods for an earthquake-induced tsunami.
Residents of approximately 75 of the 111 homes evacuated after the slide have been allowed back into their homes. The City of San Diego is not wasting any time in determining the cause of the slide. The first of three 100-ft deep exploration shafts was excavated on Friday, and a Forensic Geologist from a firm hired by the City was sent down the hole to observe geology conditions and to locate the actual slip surface. Also, claims of leaking City water and/or sewer pipes prior to the failure have begun to surface. More details in the full post. (Photo by NELVIN CEPEDA / San Diego Union-Tribune)
[Update 12/6/07] San Diego City Council approved $20 Million for the repair of Soledad Mountain Road despite concerns by some about whether funds diverted to pay for the fix will ever be repaid by Federal and State monies. Additionally, shear pin installation mentioned on the next page is scheduled to be completed by Saturday. [/Update]
A lot has happened since my last post on the Soledad Mountain Road landslide in La Jolla. Iâ€™ll try to get you caught up on the latest with remediation and legal issues. Click through for the summary.