A decade of seismicity reveals the strangely symmetrical distribution of earthquake clusters located beyond the ends of the 1872 Mw~7.6 earthquake. Both clusters enclose mixtures of hot springs, and extensional (‘normal’) faults and strike-slip faults, as well as sporadic eruptions in the past 12,000 or so years. Because of the hot springs, both have geothermal power plants. Several M>6 shocks struck in the 1980’s in the northern cluster, and several M~5 quakes struck in the 1990’s in the southern cluster.

A decade of seismicity reveals the strangely symmetrical distribution of earthquake clusters located beyond the ends of the 1872 Mw~7.6 earthquake. Both clusters enclose mixtures of hot springs, and extensional (‘normal’) faults and strike-slip faults, as well as sporadic eruptions in the past 12,000 or so years. Because of the hot springs, both have geothermal power plants. Several M>6 shocks struck in the 1980’s in the northern cluster, and several M~5 quakes struck in the 1990’s in the southern cluster.

A decade of seismicity reveals the strangely symmetrical distribution of earthquake clusters located beyond the ends of the 1872 Mw~7.6 earthquake. Both clusters enclose mixtures of hot springs, and extensional (‘normal’) faults and strike-slip faults, as well as sporadic eruptions in the past 12,000 or so years. Because of the hot springs, both have geothermal power plants. Several M>6 shocks struck in the 1980’s in the northern cluster, and several M~5 quakes struck in the 1990’s in the southern cluster.