Image: Pipes Canyon Intrusion (lava making the surface) of Basalt near Landers. Image by C Liechtenstein.
The Mojave Young Volcano System, and the hot magma below, is live and well in my opinion. Of course, we still do not know for sure. But is the local young volcanos within the ECSZ linked to the extension of the Great Basin region, which includes much of the Mojave Desert? Is this a rifting zone? Indeed it's a region of land pulling apart, as far as geologists usually agree.
Here's a cool and fetching note from a paper written by a geologist about the area I live in, and about a young volcano I live close to. This from the paper: "searching for the pliocene: field trip guide to the southern exposures":
:86.9 (1.6) Continue past New Dixie Mine Road. Ruby Mountain to the right (west) may be one of the vents for local basalt flows. It is an alkaline basalt (basanite) intrusion and flow complex of late Miocene age (6-10 Ma) (Neville, 1986). The local termination of alkaline basalt volcanism near the San Bernardino Mountains appears to coincide with estimates of the beginning of transpres- sional tectonics for the region (Sadler and Reeder, 1983). Basalt from this source can be recognized by entrained megacrysts formed in the mantle of the chrome- diopside group, including kaersutite (Wilshire and Shervais, 1975)."