Correction to “Comprehensive analysis of earthquake source spectra and swarms in the Salton Trough, California”

Authors

  • X. Chen,

  • P.M. Shearer

Errata

This article corrects:

  1. Comprehensive analysis of earthquake source spectra and swarms in the Salton Trough, California Volume 116, Issue B9, Article first published online: 23 September 2011

[1] In Chen and Shearer [2011], we compared well injection data from the Salton Sea geothermal site with nearby seismicity. The detailed injection record for each injection well can be downloaded from the “geostream for geothermal resources” website and include total injection volume and duration for each month. However, we incorrectly interpreted the duration to be the starting date of discrete injection events, which we compared with the occurrence time of individual seismicity swarms. This misinterpretation led to apparently more precise temporal correlations between injection times and swarm activity than can be obtained from the injection data. The injection activities are continuous, and the exact injection start and stop times for each well are not included in the records that we obtained. This error does not affect our main results, including the longer-term correlations between injection activities and seismicity, as well as the stress drop behavior with distance from injection wells.

[2] The specific corrections are as follows:

  1. [3] In Figure 8 in Chen and Shearer (2011) (Figure 1), the lines indicating exact timing for injection are removed from Figure 8(c).

  2. [4] In section 6.3, the sentence “The swarms are located within the Salton Sea and Brawley geothermal fields, close to geothermal wells, especially the three swarms that started shortly after nearby injection events” should be changed to “The swarms are located within the Salton Sea and Brawley geothermal fields, close to geothermal wells, especially the three swarms that occurred within active injection periods.”

  3. [5] In paragraph 34, the opening sentence “The large swarm in August, 2005 started less than 10 hours after a cluster of injection events, and exhibits NE-SW migration during the initial 10 hours” should be changed to “The large swarm in August 2005 is located within an area with a cluster of continuous injection wells and exhibits NE-SW migration during the initial 10 h.”

  4. [6] In paragraph 34, the phrase in the last sentence “The increased pore fluid pressure from multiple injectio7n events prior to the seismicity may have” should be changed to “The increased fluid pressure from multiple injection wells nearby may have.”

  5. [7] In paragraph 37, the reference to Figure 8c in the last sentence should be removed. However, the fact that multiple injection wells are active at the same time remains a valid point.

Figure 1.

(a) Map view of the August 2005 swarm with events colored by their occurrence times. (b) Map view of the 2005 swarm with events colored by their stress drop values. (c) Stress drop versus time for the 2005 swarm. The red dots are median values for 10 bins with an equal number of events. Black “+” in Figures 1a and 1b are injection wells that are active during the swarm period.

Acknowledgment

[8] We thank Lia Lajoie for pointing out the injection data problem.