When the Big One Strikes Again—Estimated Losses due to a Repeat of the 1906 San Francisco Earthquake

Abstract

This paper presents interim results of an ongoing study of building damage and losses likely to occur due to a repeat of the 1906 San Francisco earthquake, using the HAZUS technology. Recent work by Boatwright et. al. (2006) provides MMI-based ShakeMap estimates of spectral response accelerations derived from observations of intensities in the 1906 San Francisco earthquake. This paper calculates damage and loss estimates using those estimated ground motions, then compares the resulting estimates with those calculated using a method parallel with that of current seismic provisions of building codes for a magnitude M7.9 event on the San Andreas Fault, and contrasts differences in damage and loss patterns for these two scenarios. The study region of interest comprises 19 counties of the greater San Francisco Bay Area and adjacent areas of Northern California, covering 24,000 square miles, with a population of more than ten million people and about $1.5 trillion of building and contents exposure. The majority of this property and population is within 40 km (25 miles) of the San Andreas Fault. The current population of this Northern California region is about ten times what it was in 1906, and the replacement value of buildings is about 500 times greater. Despite improvements in building codes and construction practices, the growth of the region over the past 100 years causes the range of estimated fatalities, approximately 800–3,400 depending on time of day and other variables, to be comparable to what it was in 1906. The forecast property loss to buildings for a repeat of the 1906 earthquake is in the range of approximately $90–120 billion; 7,000–10,000 commercial buildings in the region are estimated to be closed due to serious damage; and about 160,000–250,000 households calculated to be displaced from damaged residences. Losses due to fire following earthquake, as well as losses to utility and transportation systems, would be in addition to these estimates.

Simulation-Based Fragility Relationships for Unreinforced Masonry Buildings

“…The relatively low casualties experienced in California is attributed mainly to the fact that the building stock is in excess of 90% wood construction designed to withstand moderate to severe shaking (Kircher et al 2006). In contrast, the building stock of Iran is composed of 80% adobe and non-engineered Numerous additional studies have revealed that the death toll of several other notable earthquakes is largely dependent on non-engineered masonry buildings which perform poorly even under moderate ground shaking.…”

“…However, similar studies to those listed above have been performed for other cities throughout the world, including Lisbon, Portugal (D'Ayala et al, 1997;Ramos and Lourenco, 2004), Basel, Switzerland (Fah et al, 2001), Istanbul, Turkey (Erdik et al, 2003), Potenza, Italy (Dolce et al, 2006), San Francisco, USA (Kircher et al, 2006) and many others of various size and scope.…”

Normalized Earthquake Damage and Fatalities in the United States: 1900–2005

“…With mitigation of 1% and 2% per year the 1906 quake adjusts to 8,900 and 3,250 deaths, respectively. The difference between the values presented here with mitigation and Kircher et al ͑2006a͒, when compared to the normalized economic losses suggest a hypothesis that U.S. ͑and California͒ earthquake policy has been more successful in its focus on reducing loss of human life than economic damage. This is certainly the situation with respect to hurricanes, where loss of A majority of high-fatality events occurred prior to the era of modern building codes, but after all events are adjusted, recent California quakes of 1971 ͑San Fernando͒, 1989 ͑Loma Prieta͒ and 1994 ͑Northridge͒ are the 6th, 9th, and 10th most deadly events.…”

Assessing Potential Earthquake Loss in Mérida State, Venezuela Using Hazus

“…The software was adopted successfully in several states in the United States (for example, Buika 2000; Kircher et al 2006a;Tantala et al 2008;Rein and Corotis 2013) and it is continually tested using U.S. as well as international earthquakes (Kircher 2003;Chock et al 2006;Remo and Pinter 2012). Hazus is also used in several other countries (for example, Gulati 2006;Korkmaz 2009;Ploeger et al 2010;Nastev 2013;Levi et al 2014).…”