Earthquake Science Center

Harrat Lunayyir is a volcanic field in Saudi Arabia that experienced a Mw~5.4 earthquake driven by an upper-crustal dike intrusion in May 2009. This volcanic field has exhibited numerous forms of volcanic seismicity both prior to and since the 2009 dike intrusion. Significantly, earthquakes within the lithospheric mantle and, rarely, the lower crust are present in the two-decade long...

Given the likelihood of future M9 Cascadia Subduction Zone (CSZ) earthquakes, various estimates of the resulting, regional ground motions have been made, including a suite of 30 physics-based simulations that reflect key modeling uncertainties. However, because the last CSZ interface rupture occurred in 1700 CE, the shaking expected in such an event is especially uncertain, as are the...

In this chapter I discuss the use of so-called macroseismic data, i.e., reports of damage and other effects of shaking on humans and the built environment, to improve the characterization of earthquakes and the ground motions they produce. Macroseismic data are critical not only to investigate earthquakes that occurred before the start of the instrumental era in seismology, but are also...